summaryrefslogtreecommitdiff
path: root/doc/administration/packages/container_registry.md
blob: 619ec2490a7a6c95ffaf00bd14f3a03f82064157 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
---
stage: Package
group: Container Registry
info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/product/ux/technical-writing/#assignments
---

# GitLab Container Registry administration **(FREE SELF)**

With the GitLab Container Registry, every project can have its
own space to store Docker images.

Read more about the Docker Registry in [the Docker documentation](https://docs.docker.com/registry/introduction/).

This document is the administrator's guide. To learn how to use the GitLab Container
Registry, see the [user documentation](../../user/packages/container_registry/index.md).

## Enable the Container Registry

**Omnibus GitLab installations**

If you installed GitLab by using the Omnibus installation package, the Container Registry
may or may not be available by default.

The Container Registry is automatically enabled and available on your GitLab domain, port 5050 if:

- You're using the built-in [Let's Encrypt integration](https://docs.gitlab.com/omnibus/settings/ssl.html#enable-the-lets-encrypt-integration), and
- You're using GitLab 12.5 or later.

Otherwise, the Container Registry is not enabled. To enable it:

- You can configure it for your [GitLab domain](#configure-container-registry-under-an-existing-gitlab-domain), or
- You can configure it for [a different domain](#configure-container-registry-under-its-own-domain).

The Container Registry works under HTTPS by default. You can use HTTP
but it's not recommended and is beyond the scope of this document.
Read the [insecure Registry documentation](https://docs.docker.com/registry/insecure/)
if you want to implement this.

**Installations from source**

If you have installed GitLab from source:

1. You must [deploy a registry](https://docs.docker.com/registry/deploying/) using the image corresponding to the
   version of GitLab you are installing
   (for example: `registry.gitlab.com/gitlab-org/build/cng/gitlab-container-registry:v3.15.0-gitlab`)
1. After the installation is complete, to enable it, you must configure the Registry's
   settings in `gitlab.yml`.
1. Use the sample NGINX configuration file from under
   [`lib/support/nginx/registry-ssl`](https://gitlab.com/gitlab-org/gitlab/-/blob/master/lib/support/nginx/registry-ssl) and edit it to match the
   `host`, `port`, and TLS certificate paths.

The contents of `gitlab.yml` are:

```yaml
registry:
  enabled: true
  host: registry.gitlab.example.com
  port: 5005
  api_url: http://localhost:5000/
  key: config/registry.key
  path: shared/registry
  issuer: gitlab-issuer
```

Where:

| Parameter | Description |
| --------- | ----------- |
| `enabled` | `true` or `false`. Enables the Registry in GitLab. By default this is `false`. |
| `host`    | The host URL under which the Registry runs and users can use. |
| `port`    | The port the external Registry domain listens on. |
| `api_url` | The internal API URL under which the Registry is exposed. It defaults to `http://localhost:5000`. Do not change this unless you are setting up an [external Docker registry](#use-an-external-container-registry-with-gitlab-as-an-auth-endpoint). |
| `key`     | The private key location that is a pair of Registry's `rootcertbundle`. Read the [token auth configuration documentation](https://docs.docker.com/registry/configuration/#token). |
| `path`    | This should be the same directory like specified in Registry's `rootdirectory`. Read the [storage configuration documentation](https://docs.docker.com/registry/configuration/#storage). This path needs to be readable by the GitLab user, the web-server user and the Registry user. Read more in [#configure-storage-for-the-container-registry](#configure-storage-for-the-container-registry). |
| `issuer`  | This should be the same value as configured in Registry's `issuer`. Read the [token auth configuration documentation](https://docs.docker.com/registry/configuration/#token). |

A Registry init file is not shipped with GitLab if you install it from source.
Hence, [restarting GitLab](../restart_gitlab.md#installations-from-source) does not restart the Registry should
you modify its settings. Read the upstream documentation on how to achieve that.

At the **absolute** minimum, make sure your [Registry configuration](https://docs.docker.com/registry/configuration/#auth)
has `container_registry` as the service and `https://gitlab.example.com/jwt/auth`
as the realm:

```yaml
auth:
  token:
    realm: https://gitlab.example.com/jwt/auth
    service: container_registry
    issuer: gitlab-issuer
    rootcertbundle: /root/certs/certbundle
```

WARNING:
If `auth` is not set up, users can pull Docker images without authentication.

## Container Registry domain configuration

There are two ways you can configure the Registry's external domain. Either:

- [Use the existing GitLab domain](#configure-container-registry-under-an-existing-gitlab-domain).
  The Registry listens on a port and reuses the TLS certificate from GitLab.
- [Use a completely separate domain](#configure-container-registry-under-its-own-domain) with a new TLS certificate
  for that domain.

Because the Container Registry requires a TLS certificate, cost may be a factor.

Take this into consideration before configuring the Container Registry
for the first time.

### Configure Container Registry under an existing GitLab domain

If the Registry is configured to use the existing GitLab domain, you can
expose the Registry on a port. This way you can reuse the existing GitLab TLS
certificate.

If the GitLab domain is `https://gitlab.example.com` and the port to the outside world is `5050`, here is what you need to set
in `gitlab.rb` or `gitlab.yml` if you are using Omnibus GitLab or installed
GitLab from source respectively.

Ensure you choose a port different than the one that Registry listens to (`5000` by default),
otherwise conflicts occur.

NOTE:
Host and container firewall rules must be configured to allow traffic in through the port listed
under the `registry_external_url` line, rather than the port listed under
`gitlab_rails['registry_port']` (default `5000`).

**Omnibus GitLab installations**

1. Your `/etc/gitlab/gitlab.rb` should contain the Registry URL as well as the
   path to the existing TLS certificate and key used by GitLab:

   ```ruby
   registry_external_url 'https://gitlab.example.com:5050'
   ```

   The `registry_external_url` is listening on HTTPS under the
   existing GitLab URL, but on a different port.

   If your TLS certificate is not in `/etc/gitlab/ssl/gitlab.example.com.crt`
   and key not in `/etc/gitlab/ssl/gitlab.example.com.key` uncomment the lines
   below:

   ```ruby
   registry_nginx['ssl_certificate'] = "/path/to/certificate.pem"
   registry_nginx['ssl_certificate_key'] = "/path/to/certificate.key"
   ```

1. Save the file and [reconfigure GitLab](../restart_gitlab.md#omnibus-gitlab-reconfigure)
   for the changes to take effect.

1. Validate using:

   ```shell
   openssl s_client -showcerts -servername gitlab.example.com -connect gitlab.example.com:5050 > cacert.pem
   ```

If your certificate provider provides the CA Bundle certificates, append them to the TLS certificate file.

An administrator may want the container registry listening on an arbitrary port such as `5678`.
However, the registry and application server are behind an AWS application load balancer that only
listens on ports `80` and `443`. The administrator may remove the port number for
`registry_external_url`, so HTTP or HTTPS is assumed. Then, the rules apply that map the load
balancer to the registry from ports `80` or `443` to the arbitrary port. This is important if users
rely on the `docker login` example in the container registry. Here's an example:

```ruby
registry_external_url 'https://registry-gitlab.example.com'
registry_nginx['redirect_http_to_https'] = true
registry_nginx['listen_port'] = 5678
```

**Installations from source**

1. Open `/home/git/gitlab/config/gitlab.yml`, find the `registry` entry and
   configure it with the following settings:

   ```yaml
   registry:
     enabled: true
     host: gitlab.example.com
     port: 5050
   ```

1. Save the file and [restart GitLab](../restart_gitlab.md#installations-from-source) for the changes to take effect.
1. Make the relevant changes in NGINX as well (domain, port, TLS certificates path).

Users should now be able to sign in to the Container Registry with their GitLab
credentials using:

```shell
docker login gitlab.example.com:5050
```

### Configure Container Registry under its own domain

When the Registry is configured to use its own domain, you need a TLS
certificate for that specific domain (for example, `registry.example.com`). You might need
a wildcard certificate if hosted under a subdomain of your existing GitLab
domain. For example, `*.gitlab.example.com`, is a wildcard that matches `registry.gitlab.example.com`,
and is distinct from `*.example.com`.

As well as manually generated SSL certificates (explained here), certificates automatically
generated by Let's Encrypt are also [supported in Omnibus installs](https://docs.gitlab.com/omnibus/settings/ssl.html).

Let's assume that you want the container Registry to be accessible at
`https://registry.gitlab.example.com`.

**Omnibus GitLab installations**

1. Place your TLS certificate and key in
   `/etc/gitlab/ssl/registry.gitlab.example.com.crt` and
   `/etc/gitlab/ssl/registry.gitlab.example.com.key` and make sure they have
   correct permissions:

   ```shell
   chmod 600 /etc/gitlab/ssl/registry.gitlab.example.com.*
   ```

1. After the TLS certificate is in place, edit `/etc/gitlab/gitlab.rb` with:

   ```ruby
   registry_external_url 'https://registry.gitlab.example.com'
   ```

   The `registry_external_url` is listening on HTTPS.

1. Save the file and [reconfigure GitLab](../restart_gitlab.md#omnibus-gitlab-reconfigure) for the changes to take effect.

If you have a [wildcard certificate](https://en.wikipedia.org/wiki/Wildcard_certificate), you must specify the path to the
certificate in addition to the URL, in this case `/etc/gitlab/gitlab.rb`
looks like:

```ruby
registry_nginx['ssl_certificate'] = "/etc/gitlab/ssl/certificate.pem"
registry_nginx['ssl_certificate_key'] = "/etc/gitlab/ssl/certificate.key"
```

**Installations from source**

1. Open `/home/git/gitlab/config/gitlab.yml`, find the `registry` entry and
   configure it with the following settings:

   ```yaml
   registry:
     enabled: true
     host: registry.gitlab.example.com
   ```

1. Save the file and [restart GitLab](../restart_gitlab.md#installations-from-source) for the changes to take effect.
1. Make the relevant changes in NGINX as well (domain, port, TLS certificates path).

Users should now be able to sign in to the Container Registry using their GitLab
credentials:

```shell
docker login registry.gitlab.example.com
```

## Disable Container Registry site-wide

When you disable the Registry by following these steps, you do not
remove any existing Docker images. This is handled by the
Registry application itself.

**Omnibus GitLab**

1. Open `/etc/gitlab/gitlab.rb` and set `registry['enable']` to `false`:

   ```ruby
   registry['enable'] = false
   ```

1. Save the file and [reconfigure GitLab](../restart_gitlab.md#omnibus-gitlab-reconfigure) for the changes to take effect.

**Installations from source**

1. Open `/home/git/gitlab/config/gitlab.yml`, find the `registry` entry and
   set `enabled` to `false`:

   ```yaml
   registry:
     enabled: false
   ```

1. Save the file and [restart GitLab](../restart_gitlab.md#installations-from-source) for the changes to take effect.

## Disable Container Registry for new projects site-wide

If the Container Registry is enabled, then it should be available on all new
projects. To disable this function and let the owners of a project to enable
the Container Registry by themselves, follow the steps below.

**Omnibus GitLab installations**

1. Edit `/etc/gitlab/gitlab.rb` and add the following line:

   ```ruby
   gitlab_rails['gitlab_default_projects_features_container_registry'] = false
   ```

1. Save the file and [reconfigure GitLab](../restart_gitlab.md#omnibus-gitlab-reconfigure) for the changes to take effect.

**Installations from source**

1. Open `/home/git/gitlab/config/gitlab.yml`, find the `default_projects_features`
   entry and configure it so that `container_registry` is set to `false`:

   ```yaml
   ## Default project features settings
   default_projects_features:
     issues: true
     merge_requests: true
     wiki: true
     snippets: false
     builds: true
     container_registry: false
   ```

1. Save the file and [restart GitLab](../restart_gitlab.md#installations-from-source) for the changes to take effect.

### Increase token duration

In GitLab, tokens for the Container Registry expire every five minutes.
To increase the token duration:

1. On the top bar, select **Main menu > Admin**.
1. On the left sidebar, select **Settings > CI/CD**.
1. Expand **Container Registry**.
1. For the **Authorization token duration (minutes)**, update the value.
1. Select **Save changes**.

## Configure storage for the Container Registry

NOTE:
For storage backends that support it, you can use object versioning to preserve, retrieve, and
restore the non-current versions of every object stored in your buckets. However, this may result in
higher storage usage and costs. Due to how the registry operates, image uploads are first stored in
a temporary path and then transferred to a final location. For object storage backends, including S3
and GCS, this transfer is achieved with a copy followed by a delete. With object versioning enabled,
these deleted temporary upload artifacts are kept as non-current versions, therefore increasing the
storage bucket size. To ensure that non-current versions are deleted after a given amount of time,
you should configure an object lifecycle policy with your storage provider.

WARNING:
Do not directly modify the files or objects stored by the container registry. Anything other than the registry writing or deleting these entries can lead to instance-wide data consistency and instability issues from which recovery may not be possible.

You can configure the Container Registry to use various storage backends by
configuring a storage driver. By default the GitLab Container Registry
is configured to use the [file system driver](#use-file-system)
configuration.

The different supported drivers are:

| Driver       | Description                          |
|--------------|--------------------------------------|
| `filesystem` | Uses a path on the local file system |
| `azure`      | Microsoft Azure Blob Storage         |
| `gcs`        | Google Cloud Storage                 |
| `s3`         | Amazon Simple Storage Service. Be sure to configure your storage bucket with the correct [S3 Permission Scopes](https://docs.docker.com/registry/storage-drivers/s3/#s3-permission-scopes). |
| `swift`      | OpenStack Swift Object Storage       |
| `oss`        | Aliyun OSS                           |

Although most S3 compatible services (like [MinIO](https://min.io/)) should work with the Container Registry, we only guarantee support for AWS S3. Because we cannot assert the correctness of third-party S3 implementations, we can debug issues, but we cannot patch the registry unless an issue is reproducible against an AWS S3 bucket.

Read more about the individual driver's configuration options in the
[Docker Registry docs](https://docs.docker.com/registry/configuration/#storage).

### Use file system

If you want to store your images on the file system, you can change the storage
path for the Container Registry, follow the steps below.

This path is accessible to:

- The user running the Container Registry daemon.
- The user running GitLab.

All GitLab, Registry, and web server users must
have access to this directory.

**Omnibus GitLab installations**

The default location where images are stored in Omnibus, is
`/var/opt/gitlab/gitlab-rails/shared/registry`. To change it:

1. Edit `/etc/gitlab/gitlab.rb`:

   ```ruby
   gitlab_rails['registry_path'] = "/path/to/registry/storage"
   ```

1. Save the file and [reconfigure GitLab](../restart_gitlab.md#omnibus-gitlab-reconfigure) for the changes to take effect.

**Installations from source**

The default location where images are stored in source installations, is
`/home/git/gitlab/shared/registry`. To change it:

1. Open `/home/git/gitlab/config/gitlab.yml`, find the `registry` entry and
   change the `path` setting:

   ```yaml
   registry:
     path: shared/registry
   ```

1. Save the file and [restart GitLab](../restart_gitlab.md#installations-from-source) for the changes to take effect.

### Use object storage

If you want to store your images on object storage, you can change the storage
driver for the Container Registry.

[Read more about using object storage with GitLab](../object_storage.md).

WARNING:
GitLab does not back up Docker images that are not stored on the
file system. Enable backups with your object storage provider if
desired.

**Omnibus GitLab installations**

To configure the `s3` storage driver in Omnibus:

1. Edit `/etc/gitlab/gitlab.rb`:

   ```ruby
   registry['storage'] = {
     's3' => {
       'accesskey' => 's3-access-key',
       'secretkey' => 's3-secret-key-for-access-key',
       'bucket' => 'your-s3-bucket',
       'region' => 'your-s3-region',
       'regionendpoint' => 'your-s3-regionendpoint'
     }
   }
   ```

   To avoid using static credentials, use an
   [IAM role](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/iam-roles-for-amazon-ec2.html)
   and omit `accesskey` and `secretkey`. Make sure that your IAM profile follows
   [the permissions documented by Docker](https://docs.docker.com/registry/storage-drivers/s3/#s3-permission-scopes).

   ```ruby
   registry['storage'] = {
     's3' => {
       'bucket' => 'your-s3-bucket',
       'region' => 'your-s3-region'
     }
   }
   ```

   If using with an [AWS S3 VPC endpoint](https://docs.aws.amazon.com/vpc/latest/privatelink/vpc-endpoints-s3.html),
   then set `regionendpoint` to your VPC endpoint address and set `pathstyle` to false:

   ```ruby
   registry['storage'] = {
     's3' => {
       'accesskey' => 's3-access-key',
       'secretkey' => 's3-secret-key-for-access-key',
       'bucket' => 'your-s3-bucket',
       'region' => 'your-s3-region',
       'regionendpoint' => 'your-s3-vpc-endpoint',
       'pathstyle' => false
     }
   }
   ```

   - `regionendpoint` is only required when configuring an S3 compatible service such as MinIO, or
     when using an AWS S3 VPC Endpoint.
   - `your-s3-bucket` should be the name of a bucket that exists, and can't include subdirectories.
   - `pathstyle` should be set to true to use `host/bucket_name/object` style paths instead of
     `bucket_name.host/object`. [Set to false for AWS S3](https://aws.amazon.com/blogs/aws/amazon-s3-path-deprecation-plan-the-rest-of-the-story/).

   You can set a rate limit on connections to S3 to avoid 503 errors from the S3 API. To do this,
   set `maxrequestspersecond` to a number within the [S3 request rate threshold](https://repost.aws/knowledge-center/s3-503-within-request-rate-prefix):

   ```ruby
      registry['storage'] = {
      's3' => {
        'accesskey' => 's3-access-key',
        'secretkey' => 's3-secret-key-for-access-key',
        'bucket' => 'your-s3-bucket',
        'region' => 'your-s3-region',
        'regionendpoint' => 'your-s3-regionendpoint',
        'maxrequestspersecond' => 100
      }
    }
   ```

1. Save the file and [reconfigure GitLab](../restart_gitlab.md#omnibus-gitlab-reconfigure) for the changes to take effect.

**Installations from source**

Configuring the storage driver is done in the registry configuration YAML file created
when you [deployed your Docker registry](https://docs.docker.com/registry/deploying/).

`s3` storage driver example:

```yaml
storage:
  s3:
    accesskey: 's3-access-key'                # Not needed if IAM role used
    secretkey: 's3-secret-key-for-access-key' # Not needed if IAM role used
    bucket: 'your-s3-bucket'
    region: 'your-s3-region'
    regionendpoint: 'your-s3-regionendpoint'
  cache:
    blobdescriptor: inmemory
  delete:
    enabled: true
```

`your-s3-bucket` should be the name of a bucket that exists, and can't include subdirectories.

#### Migrate to object storage without downtime

WARNING:
Using [AWS DataSync](https://aws.amazon.com/datasync/)
to copy the registry data to or between S3 buckets creates invalid metadata objects in the bucket.
For additional details, see [Tags with an empty name](#tags-with-an-empty-name).
To move data to and between S3 buckets, the AWS CLI `sync` operation is recommended.

To migrate storage without stopping the Container Registry, set the Container Registry
to read-only mode. On large instances, this may require the Container Registry
to be in read-only mode for a while. During this time,
you can pull from the Container Registry, but you cannot push.

1. Optional: To reduce the amount of data to be migrated, run the [garbage collection tool without downtime](#performing-garbage-collection-without-downtime).
1. This example uses the `aws` CLI. If you haven't configured the
   CLI before, you have to configure your credentials by running `sudo aws configure`.
   Because a non-administrator user likely can't access the Container Registry folder,
   ensure you use `sudo`. To check your credential configuration, run
   [`ls`](https://awscli.amazonaws.com/v2/documentation/api/latest/reference/s3/ls.html) to list
   all buckets.

   ```shell
   sudo aws --endpoint-url https://your-object-storage-backend.com s3 ls
   ```

   If you are using AWS as your back end, you do not need the [`--endpoint-url`](https://docs.aws.amazon.com/cli/latest/reference/#options).
1. Copy initial data to your S3 bucket, for example with the `aws` CLI
   [`cp`](https://awscli.amazonaws.com/v2/documentation/api/latest/reference/s3/cp.html)
   or [`sync`](https://awscli.amazonaws.com/v2/documentation/api/latest/reference/s3/sync.html)
   command. Make sure to keep the `docker` folder as the top-level folder inside the bucket.

   ```shell
   sudo aws --endpoint-url https://your-object-storage-backend.com s3 sync registry s3://mybucket
   ```

   NOTE:
   If you have a lot of data, you may be able to improve performance by
   [running parallel sync operations](https://repost.aws/knowledge-center/s3-improve-transfer-sync-command).

1. To perform the final data sync,
   [put the Container Registry in `read-only` mode](#performing-garbage-collection-without-downtime) and
   [reconfigure GitLab](../restart_gitlab.md#omnibus-gitlab-reconfigure).
1. Sync any changes since the initial data load to your S3 bucket and delete files that exist in the destination bucket but not in the source:

   ```shell
   sudo aws --endpoint-url https://your-object-storage-backend.com s3 sync registry s3://mybucket --delete --dryrun
   ```

   After verifying the command performs as expected, remove the
   [`--dryrun`](https://docs.aws.amazon.com/cli/latest/reference/s3/sync.html)
   flag and run the command.

   WARNING:
   The [`--delete`](https://docs.aws.amazon.com/cli/latest/reference/s3/sync.html)
   flag deletes files that exist in the destination but not in the source.
   If you swap the source and destination, all data in the Registry is deleted.

1. Verify all Container Registry files have been uploaded to object storage
   by looking at the file count returned by these two commands:

   ```shell
   sudo find registry -type f | wc -l
   ```

   ```shell
   sudo aws --endpoint-url https://your-object-storage-backend.com s3 ls s3://mybucket --recursive | wc -l
   ```

   The output of these commands should match, except for the content in the
   `_uploads` directories and sub-directories.
1. Configure your registry to [use the S3 bucket for storage](#use-object-storage).
1. For the changes to take effect, set the Registry back to `read-write` mode and [reconfigure GitLab](../restart_gitlab.md#omnibus-gitlab-reconfigure).

#### Moving to Azure Object Storage

> The default configuration for the storage driver will be [changed](https://gitlab.com/gitlab-org/container-registry/-/issues/854) in GitLab 16.0.

<!--- start_remove The following content will be removed on remove_date: '2023-10-22' -->
WARNING:
The default configuration for the storage driver will be [changed](https://gitlab.com/gitlab-org/container-registry/-/issues/854) in GitLab 16.0. The storage driver will use `/` as the default root directory. You can add `trimlegacyrootprefix: false` to your current configuration now to avoid any disruptions. For more information, see the [Container Registry configuration](https://gitlab.com/gitlab-org/container-registry/-/tree/master/docs-gitlab#azure-storage-driver) documentation.
<!--- end_remove -->

When moving from an existing file system or another object storage provider to Azure Object Storage, you must configure the registry to use the standard root directory.
This configuration is done by setting [`trimlegacyrootprefix: true]`](https://gitlab.com/gitlab-org/container-registry/-/blob/a3f64464c3ec1c5a599c0a2daa99ebcbc0100b9a/docs-gitlab/README.md#azure-storage-driver) in the Azure storage driver section of the registry configuration.
Without this configuration, the Azure storage driver uses `//` instead of `/` as the first section of the root path, rendering the migrated images inaccessible.

**Omnibus GitLab installations**

```ruby
registry['storage'] = {
  'azure' => {
    'accountname' => 'accountname',
    'accountkey' => 'base64encodedaccountkey',
    'container' => 'containername',
    'rootdirectory' => '/azure/virtual/container',
    'trimlegacyrootprefix' => true
  }
}
```

**Installations from source**

```yaml
storage:
  azure:
    accountname: accountname
    accountkey: base64encodedaccountkey
    container: containername
    rootdirectory: /azure/virtual/container
    trimlegacyrootprefix: true
```

By default, Azure Storage Driver uses the `core.windows.net` realm. You can set another value for `realm` in the `azure` section (for example, `core.usgovcloudapi.net` for Azure Government Cloud). For more information, see the [Docker documentation](https://docs.docker.com/registry/storage-drivers/azure/).

### Disable redirect for storage driver

By default, users accessing a registry configured with a remote backend are redirected to the default backend for the storage driver. For example, registries can be configured using the `s3` storage driver, which redirects requests to a remote S3 bucket to alleviate load on the GitLab server.

However, this behavior is undesirable for registries used by internal hosts that usually can't access public servers. To disable redirects and [proxy download](../object_storage.md#proxy-download), set the `disable` flag to true as follows. This makes all traffic always go through the Registry service. This results in improved security (less surface attack as the storage backend is not publicly accessible), but worse performance (all traffic is redirected via the service).

**Omnibus GitLab installations**

1. Edit `/etc/gitlab/gitlab.rb`:

   ```ruby
   registry['storage'] = {
     's3' => {
       'accesskey' => 's3-access-key',
       'secretkey' => 's3-secret-key-for-access-key',
       'bucket' => 'your-s3-bucket',
       'region' => 'your-s3-region',
       'regionendpoint' => 'your-s3-regionendpoint'
     },
     'redirect' => {
       'disable' => true
     }
   }
   ```

1. Save the file and [reconfigure GitLab](../restart_gitlab.md#omnibus-gitlab-reconfigure) for the changes to take effect.

**Installations from source**

1. Add the `redirect` flag to your registry configuration YAML file:

   ```yaml
   storage:
     s3:
       accesskey: 'AKIAKIAKI'
       secretkey: 'secret123'
       bucket: 'gitlab-registry-bucket-AKIAKIAKI'
       region: 'your-s3-region'
       regionendpoint: 'your-s3-regionendpoint'
     redirect:
       disable: true
     cache:
       blobdescriptor: inmemory
     delete:
       enabled: true
   ```

1. Save the file and [restart GitLab](../restart_gitlab.md#installations-from-source) for the changes to take effect.

#### Encrypted S3 buckets

You can use server-side encryption with AWS KMS for S3 buckets that have
[SSE-S3 or SSE-KMS encryption enabled by default](https://docs.aws.amazon.com/kms/latest/developerguide/services-s3.html).
Customer master keys (CMKs) and SSE-C encryption aren't supported since this requires sending the
encryption keys in every request.

For SSE-S3, you must enable the `encrypt` option in the registry settings. How you do this depends
on how you installed GitLab. Follow the instructions here that match your installation method.

For Omnibus GitLab installations:

1. Edit `/etc/gitlab/gitlab.rb`:

   ```ruby
   registry['storage'] = {
     's3' => {
       'accesskey' => 's3-access-key',
       'secretkey' => 's3-secret-key-for-access-key',
       'bucket' => 'your-s3-bucket',
       'region' => 'your-s3-region',
       'regionendpoint' => 'your-s3-regionendpoint',
       'encrypt' => true
     }
   }
   ```

1. Save the file and [reconfigure GitLab](../restart_gitlab.md#omnibus-gitlab-reconfigure)
   for the changes to take effect.

For installations from source:

1. Edit your registry configuration YAML file:

   ```yaml
   storage:
     s3:
       accesskey: 'AKIAKIAKI'
       secretkey: 'secret123'
       bucket: 'gitlab-registry-bucket-AKIAKIAKI'
       region: 'your-s3-region'
       regionendpoint: 'your-s3-regionendpoint'
       encrypt: true
   ```

1. Save the file and [restart GitLab](../restart_gitlab.md#installations-from-source)
   for the changes to take effect.

### Storage limitations

Currently, there is no storage limitation, which means a user can upload an
infinite amount of Docker images with arbitrary sizes. This setting should be
configurable in future releases.

## Change the registry's internal port

The Registry server listens on localhost at port `5000` by default,
which is the address for which the Registry server should accept connections.
In the examples below we set the Registry's port to `5010`.

**Omnibus GitLab**

1. Open `/etc/gitlab/gitlab.rb` and set `registry['registry_http_addr']`:

   ```ruby
   registry['registry_http_addr'] = "localhost:5010"
   ```

1. Save the file and [reconfigure GitLab](../restart_gitlab.md#omnibus-gitlab-reconfigure) for the changes to take effect.

**Installations from source**

1. Open the configuration file of your Registry server and edit the
   [`http:addr`](https://docs.docker.com/registry/configuration/#http) value:

   ```yaml
   http:
     addr: localhost:5010
   ```

1. Save the file and restart the Registry server.

## Disable Container Registry per project

If Registry is enabled in your GitLab instance, but you don't need it for your
project, you can [disable it from your project's settings](../../user/project/settings/index.md#configure-project-visibility-features-and-permissions).

## Use an external container registry with GitLab as an auth endpoint

> Support for external container registries in GitLab is [deprecated](https://gitlab.com/gitlab-org/gitlab/-/issues/376217) in GitLab 15.8 and will be removed in GitLab 16.0.

If you use an external container registry, some features associated with the
container registry may be unavailable or have [inherent risks](../../user/packages/container_registry/reduce_container_registry_storage.md#use-with-external-container-registries).

For the integration to work, the external registry must be configured to
use a JSON Web Token to authenticate with GitLab. The
[external registry's runtime configuration](https://docs.docker.com/registry/configuration/#token)
**must** have the following entries:

```yaml
auth:
  token:
    realm: https://gitlab.example.com/jwt/auth
    service: container_registry
    issuer: gitlab-issuer
    rootcertbundle: /root/certs/certbundle
```

Without these entries, the registry logins cannot authenticate with GitLab.
GitLab also remains unaware of
[nested image names](../../user/packages/container_registry/index.md#naming-convention-for-your-container-images)
under the project hierarchy, like
`registry.example.com/group/project/image-name:tag` or
`registry.example.com/group/project/my/image-name:tag`, and only recognizes
`registry.example.com/group/project:tag`.

**Omnibus GitLab**

You can use GitLab as an auth endpoint with an external container registry.

1. Open `/etc/gitlab/gitlab.rb` and set necessary configurations:

   ```ruby
   gitlab_rails['registry_enabled'] = true
   gitlab_rails['registry_api_url'] = "https://<external_registry_host>:5000"
   gitlab_rails['registry_issuer'] = "gitlab-issuer"
   ```

   - `gitlab_rails['registry_enabled'] = true` is needed to enable GitLab
     Container Registry features and authentication endpoint. The GitLab bundled
     Container Registry service does not start, even with this enabled.
   - `gitlab_rails['registry_api_url'] = "http://<external_registry_host>:5000"`
     must be changed to match the host where Registry is installed.
     It must also specify `https` if the external registry is
     configured to use TLS. Read more on the
     [Docker registry documentation](https://docs.docker.com/registry/deploying/).

1. A certificate-key pair is required for GitLab and the external container
   registry to communicate securely. You need to create a certificate-key
   pair, configuring the external container registry with the public
   certificate (`rootcertbundle`) and configuring GitLab with the private key.
   To do that, add the following to `/etc/gitlab/gitlab.rb`:

   ```ruby
   # registry['internal_key'] should contain the contents of the custom key
   # file. Line breaks in the key file should be marked using `\n` character
   # Example:
   registry['internal_key'] = "---BEGIN RSA PRIVATE KEY---\nMIIEpQIBAA\n"

   # Optionally define a custom file for Omnibus GitLab to write the contents
   # of registry['internal_key'] to.
   gitlab_rails['registry_key_path'] = "/custom/path/to/registry-key.key"
   ```

   Each time reconfigure is executed, the file specified at `registry_key_path`
   gets populated with the content specified by `internal_key`. If
   no file is specified, Omnibus GitLab defaults it to
   `/var/opt/gitlab/gitlab-rails/etc/gitlab-registry.key` and populates
   it.

1. To change the container registry URL displayed in the GitLab Container
   Registry pages, set the following configurations:

   ```ruby
   gitlab_rails['registry_host'] = "registry.gitlab.example.com"
   gitlab_rails['registry_port'] = "5005"
   ```

1. Save the file and [reconfigure GitLab](../restart_gitlab.md#omnibus-gitlab-reconfigure)
   for the changes to take effect.

**Installations from source**

1. Open `/home/git/gitlab/config/gitlab.yml`, and edit the configuration settings under `registry`:

   ```yaml
   ## Container Registry

   registry:
     enabled: true
     host: "registry.gitlab.example.com"
     port: "5005"
     api_url: "https://<external_registry_host>:5000"
     path: /var/lib/registry
     key: /path/to/keyfile
     issuer: gitlab-issuer
   ```

   [Read more](#enable-the-container-registry) about what these parameters mean.

1. Save the file and [restart GitLab](../restart_gitlab.md#installations-from-source) for the changes to take effect.

## Configure Container Registry notifications

You can configure the Container Registry to send webhook notifications in
response to events happening within the registry.

Read more about the Container Registry notifications configuration options in the
[Docker Registry notifications documentation](https://docs.docker.com/registry/notifications/).

You can configure multiple endpoints for the Container Registry.

**Omnibus GitLab installations**

To configure a notification endpoint in Omnibus:

1. Edit `/etc/gitlab/gitlab.rb`:

   ```ruby
   registry['notifications'] = [
     {
       'name' => 'test_endpoint',
       'url' => 'https://gitlab.example.com/notify',
       'timeout' => '500ms',
       'threshold' => 5,
       'backoff' => '1s',
       'headers' => {
         "Authorization" => ["AUTHORIZATION_EXAMPLE_TOKEN"]
       }
     }
   ]
   ```

1. Save the file and [reconfigure GitLab](../restart_gitlab.md#omnibus-gitlab-reconfigure) for the changes to take effect.

**Installations from source**

Configuring the notification endpoint is done in your registry configuration YAML file created
when you [deployed your Docker registry](https://docs.docker.com/registry/deploying/).

Example:

```yaml
notifications:
  endpoints:
    - name: alistener
      disabled: false
      url: https://my.listener.com/event
      headers: <http.Header>
      timeout: 500
      threshold: 5
      backoff: 1000
```

## Run the Cleanup policy now

WARNING:
If you're using a distributed architecture and Sidekiq is running on a different node, the cleanup
policies don't work. To fix this, you must configure the `gitlab.rb` file on the Sidekiq nodes to
point to the correct registry URL and copy the `registry.key` file to each Sidekiq node. For more
information, see the [Sidekiq configuration](../sidekiq/index.md)
page.

To reduce the amount of [Container Registry disk space used by a given project](#registry-disk-space-usage-by-project),
administrators can clean up image tags
and [run garbage collection](#container-registry-garbage-collection).

### Registry Disk Space Usage by Project

To find the disk space used by each project, run the following in the
[GitLab Rails console](../operations/rails_console.md#starting-a-rails-console-session):

```ruby
projects_and_size = [["project_id", "creator_id", "registry_size_bytes", "project path"]]
# You need to specify the projects that you want to look through. You can get these in any manner.
projects = Project.last(100)

projects.each do |p|
   project_total_size = 0
   container_repositories = p.container_repositories

   container_repositories.each do |c|
       c.tags.each do |t|
          project_total_size = project_total_size + t.total_size unless t.total_size.nil?
       end
   end

   if project_total_size > 0
      projects_and_size << [p.project_id, p.creator.id, project_total_size, p.full_path]
   end
end

# print it as comma separated output
projects_and_size.each do |ps|
   puts "%s,%s,%s,%s" % ps
end
```

To remove image tags by running the cleanup policy, run the following commands in the
[GitLab Rails console](../operations/rails_console.md):

```ruby
# Numeric ID of the project whose container registry should be cleaned up
P = <project_id>

# Numeric ID of a user with Developer, Maintainer, or Owner role for the project
U = <user_id>

# Get required details / objects
user    = User.find_by_id(U)
project = Project.find_by_id(P)
policy  = ContainerExpirationPolicy.find_by(project_id: P)

# Loop through each container repository
project.container_repositories.find_each do |repo|
  puts repo.attributes

  # Start the tag cleanup
  puts Projects::ContainerRepository::CleanupTagsService.new(container_repository: repo, current_user: user, params: policy.attributes.except("created_at", "updated_at")).execute
end
```

You can also [run cleanup on a schedule](../../user/packages/container_registry/reduce_container_registry_storage.md#cleanup-policy).

## Container Registry garbage collection

NOTE:
Retention policies within your object storage provider, such as Amazon S3 Lifecycle, may prevent
objects from being properly deleted.

Container Registry can use considerable amounts of disk space. To clear up
some unused layers, the registry includes a garbage collect command.

GitLab offers a set of APIs to manipulate the Container Registry and aid the process
of removing unused tags. Currently, this is exposed using the API, but in the future,
these controls should migrate to the GitLab interface.

Users who have the [Maintainer role](../../user/permissions.md) for the project can
[delete Container Registry tags in bulk](../../api/container_registry.md#delete-registry-repository-tags-in-bulk)
periodically based on their own criteria. However, deleting the tags alone does not recycle data,
it only unlinks tags from manifests and image blobs. To recycle the Container
Registry data in the whole GitLab instance, you can use the built-in garbage collection command
provided by `gitlab-ctl`.

Prerequisites:

- You must have installed GitLab by using an Omnibus package or the
  [GitLab Helm chart](https://docs.gitlab.com/charts/charts/registry/#garbage-collection).
- You must set the Registry to [read-only mode](#performing-garbage-collection-without-downtime).
  Running garbage collection causes downtime for the Container Registry. When you run this command
  on an instance in an environment where another instance is still writing to the Registry storage,
  referenced manifests are removed.

### Understanding the content-addressable layers

Consider the following example, where you first build the image:

```shell
# This builds a image with content of sha256:111111
docker build -t my.registry.com/my.group/my.project:latest .
docker push my.registry.com/my.group/my.project:latest
```

Now, you do overwrite `:latest` with a new version:

```shell
# This builds a image with content of sha256:222222
docker build -t my.registry.com/my.group/my.project:latest .
docker push my.registry.com/my.group/my.project:latest
```

Now, the `:latest` tag points to manifest of `sha256:222222`. However, due to
the architecture of registry, this data is still accessible when pulling the
image `my.registry.com/my.group/my.project@sha256:111111`, even though it is
no longer directly accessible via the `:latest` tag.

### Recycling unused tags

Before you run the built-in command, note the following:

- The built-in command stops the registry before it starts the garbage collection.
- The garbage collect command takes some time to complete, depending on the
  amount of data that exists.
- If you changed the location of registry configuration file, you must
  specify its path.
- After the garbage collection is done, the registry should start automatically.

If you did not change the default location of the configuration file, run:

```shell
sudo gitlab-ctl registry-garbage-collect
```

This command takes some time to complete, depending on the amount of
layers you have stored.

If you changed the location of the Container Registry `config.yml`:

```shell
sudo gitlab-ctl registry-garbage-collect /path/to/config.yml
```

You may also [remove all untagged manifests and unreferenced layers](#removing-untagged-manifests-and-unreferenced-layers),
although this is a way more destructive operation, and you should first
understand the implications.

### Removing untagged manifests and unreferenced layers

WARNING:
This is a destructive operation.

The GitLab Container Registry follows the same default workflow as Docker Distribution:
retain untagged manifests and all layers, even ones that are not referenced directly. All content
can be accessed by using context addressable identifiers.

However, in most workflows, you don't care about untagged manifests and old layers if they are not directly
referenced by a tagged manifest. The `registry-garbage-collect` command supports the
`-m` switch to allow you to remove all unreferenced manifests and layers that are
not directly accessible via `tag`:

```shell
sudo gitlab-ctl registry-garbage-collect -m
```

Since this is a way more destructive operation, this behavior is disabled by default.
You are likely expecting this way of operation, but before doing that, ensure
that you have backed up all registry data.

When the command is used without the `-m` flag, the Container Registry only removes layers that are not referenced by any manifest, tagged or not.

### Performing garbage collection without downtime

You can perform garbage collection without stopping the Container Registry by putting
it in read-only mode and by not using the built-in command. On large instances
this could require Container Registry to be in read-only mode for a while.
During this time,
you are able to pull from the Container Registry, but you are not able to
push.

By default, the [registry storage path](#configure-storage-for-the-container-registry)
is `/var/opt/gitlab/gitlab-rails/shared/registry`.

To enable the read-only mode:

1. In `/etc/gitlab/gitlab.rb`, specify the read-only mode:

   ```ruby
     registry['storage'] = {
       'filesystem' => {
         'rootdirectory' => "<your_registry_storage_path>"
       },
       'maintenance' => {
         'readonly' => {
           'enabled' => true
         }
       }
     }
   ```

1. Save and reconfigure GitLab:

   ```shell
   sudo gitlab-ctl reconfigure
   ```

   This command sets the Container Registry into the read-only mode.

1. Next, trigger one of the garbage collect commands:

   WARNING:
   You must use `/opt/gitlab/embedded/bin/registry` to recycle unused tags. If you use `gitlab-ctl registry-garbage-collect`, **the container registry goes down**.

   ```shell
   # Recycling unused tags
   sudo /opt/gitlab/embedded/bin/registry garbage-collect /var/opt/gitlab/registry/config.yml

   # Removing unused layers not referenced by manifests
   sudo /opt/gitlab/embedded/bin/registry garbage-collect -m /var/opt/gitlab/registry/config.yml
   ```

   This command starts the garbage collection, which might take some time to complete.

1. Once done, in `/etc/gitlab/gitlab.rb` change it back to read-write mode:

   ```ruby
    registry['storage'] = {
      'filesystem' => {
        'rootdirectory' => "<your_registry_storage_path>"
      },
      'maintenance' => {
        'readonly' => {
          'enabled' => false
        }
      }
    }
   ```

1. Save and reconfigure GitLab:

   ```shell
   sudo gitlab-ctl reconfigure
   ```

### Running the garbage collection on schedule

Ideally, you want to run the garbage collection of the registry regularly on a
weekly basis at a time when the registry is not being in-use.
The simplest way is to add a new crontab job that it runs periodically
once a week.

Create a file under `/etc/cron.d/registry-garbage-collect`:

```shell
SHELL=/bin/sh
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin

# Run every Sunday at 04:05am
5 4 * * 0  root gitlab-ctl registry-garbage-collect
```

You may want to add the `-m` flag to [remove untagged manifests and unreferenced layers](#removing-untagged-manifests-and-unreferenced-layers).

### Stop garbage collection

If you anticipate stopping garbage collection, you should manually run garbage collection as
described in [Performing garbage collection without downtime](#performing-garbage-collection-without-downtime).
You can then stop garbage collection by pressing <kbd>Control</kbd>+<kbd>C</kbd>.

Otherwise, interrupting `gitlab-ctl` could leave your registry service in a down state. In this
case, you must find the [garbage collection process](https://gitlab.com/gitlab-org/omnibus-gitlab/-/blob/master/files/gitlab-ctl-commands/registry_garbage_collect.rb#L26-35)
itself on the system so that the `gitlab-ctl` command can bring the registry service back up again.

Also, there's no way to save progress or results during the mark phase of the process. Only once
blobs start being deleted is anything permanent done.

## Configuring GitLab and Registry to run on separate nodes (Omnibus GitLab)

By default, package assumes that both services are running on the same node.
To get GitLab and Registry to run on a separate nodes, separate configuration
is necessary for Registry and GitLab.

### Configuring Registry

Below you can find configuration options you should set in `/etc/gitlab/gitlab.rb`,
for Registry to run separately from GitLab:

- `registry['registry_http_addr']`, default [set programmatically](https://gitlab.com/gitlab-org/omnibus-gitlab/blob/10-3-stable/files/gitlab-cookbooks/gitlab/libraries/registry.rb#L50). Needs to be reachable by web server (or LB).
- `registry['token_realm']`, default [set programmatically](https://gitlab.com/gitlab-org/omnibus-gitlab/blob/10-3-stable/files/gitlab-cookbooks/gitlab/libraries/registry.rb#L53). Specifies the endpoint to use to perform authentication, usually the GitLab URL.
  This endpoint needs to be reachable by user.
- `registry['http_secret']`, [random string](https://gitlab.com/gitlab-org/omnibus-gitlab/blob/10-3-stable/files/gitlab-cookbooks/gitlab/libraries/registry.rb#L32). A random piece of data used to sign state that may be stored with the client to protect against tampering.
- `registry['internal_key']`, default [automatically generated](https://gitlab.com/gitlab-org/omnibus-gitlab/blob/10-3-stable/files/gitlab-cookbooks/gitlab/recipes/gitlab-rails.rb#L113-119). Contents of the key that GitLab uses to sign the tokens. They key gets created on the Registry server, but it is not used there.
- `gitlab_rails['registry_key_path']`, default [set programmatically](https://gitlab.com/gitlab-org/omnibus-gitlab/blob/10-3-stable/files/gitlab-cookbooks/gitlab/recipes/gitlab-rails.rb#L35). This is the path where `internal_key` contents are written to disk.
- `registry['internal_certificate']`, default [automatically generated](https://gitlab.com/gitlab-org/omnibus-gitlab/blob/10-3-stable/files/gitlab-cookbooks/registry/recipes/enable.rb#L60-66). Contents of the certificate that GitLab uses to sign the tokens.
- `registry['rootcertbundle']`, default [set programmatically](https://gitlab.com/gitlab-org/omnibus-gitlab/blob/10-3-stable/files/gitlab-cookbooks/registry/recipes/enable.rb#L60). Path to certificate. This is the path where `internal_certificate`
  contents are written to disk.
- `registry['health_storagedriver_enabled']`, default [set programmatically](https://gitlab.com/gitlab-org/omnibus-gitlab/blob/10-7-stable/files/gitlab-cookbooks/gitlab/libraries/registry.rb#L88). Configure whether health checks on the configured storage driver are enabled.
- `gitlab_rails['registry_issuer']`, [default value](https://gitlab.com/gitlab-org/omnibus-gitlab/blob/10-3-stable/files/gitlab-cookbooks/gitlab/attributes/default.rb#L153). This setting needs to be set the same between Registry and GitLab.

### Configuring GitLab

Below you can find configuration options you should set in `/etc/gitlab/gitlab.rb`,
for GitLab to run separately from Registry:

- `gitlab_rails['registry_enabled']`, must be set to `true`. This setting
  signals to GitLab that it should allow Registry API requests.
- `gitlab_rails['registry_api_url']`, default [set programmatically](https://gitlab.com/gitlab-org/omnibus-gitlab/blob/10-3-stable/files/gitlab-cookbooks/gitlab/libraries/registry.rb#L52). This is the Registry URL used internally that users do not need to interact with, `registry['registry_http_addr']` with scheme.
- `gitlab_rails['registry_host']`, for example, `registry.gitlab.example`. Registry endpoint without the scheme, the address that gets shown to the end user.
- `gitlab_rails['registry_port']`. Registry endpoint port, visible to the end user.
- `gitlab_rails['registry_issuer']` must match the issuer in the Registry configuration.
- `gitlab_rails['registry_key_path']`, path to the key that matches the certificate on the
  Registry side.
- `gitlab_rails['internal_key']`, contents of the key that GitLab uses to sign the tokens.

## Architecture of GitLab Container Registry

The GitLab registry is what users use to store their own Docker images.
Because of that the Registry is client facing, meaning that we expose it directly
on the web server (or load balancers, LB for short).

![GitLab Registry diagram](img/gitlab-registry-architecture.png)

The flow described by the diagram above:

1. A user runs `docker login registry.gitlab.example` on their client. This reaches the web server (or LB) on port 443.
1. Web server connects to the Registry backend pool (by default, using port 5000). Since the user
   didn't provide a valid token, the Registry returns a 401 HTTP code and the URL (`token_realm` from
   Registry configuration) where to get one. This points to the GitLab API.
1. The Docker client then connects to the GitLab API and obtains a token.
1. The API signs the token with the registry key and hands it to the Docker client
1. The Docker client now logs in again with the token received from the API. It can now push and pull Docker images.

Reference: <https://docs.docker.com/registry/spec/auth/token/>

### Communication between GitLab and Registry

Registry doesn't have a way to authenticate users internally so it relies on
GitLab to validate credentials. The connection between Registry and GitLab is
TLS encrypted. The key is used by GitLab to sign the tokens while the certificate
is used by Registry to validate the signature. By default, a self-signed certificate key pair is generated
for all installations. This can be overridden as needed.

GitLab interacts with the Registry using the Registry private key. When a Registry
request goes out, a new short-living (10 minutes) namespace limited token is generated
and signed with the private key.
The Registry then verifies that the signature matches the registry certificate
specified in its configuration and allows the operation.
GitLab background jobs processing (through Sidekiq) also interacts with Registry.
These jobs talk directly to Registry to handle image deletion.

## Troubleshooting

Before diving in to the following sections, here's some basic troubleshooting:

1. Check to make sure that the system clock on your Docker client and GitLab server have
   been synchronized (for example, via NTP).

1. If you are using an S3-backed Registry, double check that the IAM
   permissions and the S3 credentials (including region) are correct. See
   [the sample IAM policy](https://docs.docker.com/registry/storage-drivers/s3/)
   for more details.

1. Check the Registry logs (for example `/var/log/gitlab/registry/current`) and the GitLab production logs
   for errors (for example `/var/log/gitlab/gitlab-rails/production.log`). You may be able to find clues
   there.

### Using self-signed certificates with Container Registry

If you're using a self-signed certificate with your Container Registry, you
might encounter issues during the CI jobs like the following:

```plaintext
Error response from daemon: Get registry.example.com/v1/users/: x509: certificate signed by unknown authority
```

The Docker daemon running the command expects a cert signed by a recognized CA,
thus the error above.

While GitLab doesn't support using self-signed certificates with Container
Registry out of the box, it is possible to make it work by
[instructing the Docker daemon to trust the self-signed certificates](https://docs.docker.com/registry/insecure/#use-self-signed-certificates),
mounting the Docker daemon and setting `privileged = false` in the GitLab Runner
`config.toml` file. Setting `privileged = true` takes precedence over the Docker daemon:

```toml
  [runners.docker]
    image = "ruby:2.6"
    privileged = false
    volumes = ["/var/run/docker.sock:/var/run/docker.sock", "/cache"]
```

Additional information about this: [issue 18239](https://gitlab.com/gitlab-org/gitlab-foss/-/issues/18239).

### Docker login attempt fails with: 'token signed by untrusted key'

[Registry relies on GitLab to validate credentials](#architecture-of-gitlab-container-registry)
If the registry fails to authenticate valid login attempts, you get the following error message:

```shell
# docker login gitlab.company.com:4567
Username: user
Password:
Error response from daemon: login attempt to https://gitlab.company.com:4567/v2/ failed with status: 401 Unauthorized
```

And more specifically, this appears in the `/var/log/gitlab/registry/current` log file:

```plaintext
level=info msg="token signed by untrusted key with ID: "TOKE:NL6Q:7PW6:EXAM:PLET:OKEN:BG27:RCIB:D2S3:EXAM:PLET:OKEN""
level=warning msg="error authorizing context: invalid token" go.version=go1.12.7 http.request.host="gitlab.company.com:4567" http.request.id=74613829-2655-4f96-8991-1c9fe33869b8 http.request.method=GET http.request.remoteaddr=10.72.11.20 http.request.uri="/v2/" http.request.useragent="docker/19.03.2 go/go1.12.8 git-commit/6a30dfc kernel/3.10.0-693.2.2.el7.x86_64 os/linux arch/amd64 UpstreamClient(Docker-Client/19.03.2 \(linux\))"
```

GitLab uses the contents of the certificate key pair's two sides to encrypt the authentication token
for the Registry. This message means that those contents do not align.

Check which files are in use:

- `grep -A6 'auth:' /var/opt/gitlab/registry/config.yml`

  ```yaml
  ## Container Registry Certificate
     auth:
       token:
         realm: https://gitlab.my.net/jwt/auth
         service: container_registry
         issuer: omnibus-gitlab-issuer
    -->  rootcertbundle: /var/opt/gitlab/registry/gitlab-registry.crt
         autoredirect: false
  ```

- `grep -A9 'Container Registry' /var/opt/gitlab/gitlab-rails/etc/gitlab.yml`

  ```yaml
  ## Container Registry Key
     registry:
       enabled: true
       host: gitlab.company.com
       port: 4567
       api_url: http://127.0.0.1:5000 # internal address to the registry, is used by GitLab to directly communicate with API
       path: /var/opt/gitlab/gitlab-rails/shared/registry
  -->  key: /var/opt/gitlab/gitlab-rails/etc/gitlab-registry.key
       issuer: omnibus-gitlab-issuer
       notification_secret:
  ```

The output of these `openssl` commands should match, proving that the cert-key pair is a match:

```shell
/opt/gitlab/embedded/bin/openssl x509 -noout -modulus -in /var/opt/gitlab/registry/gitlab-registry.crt | /opt/gitlab/embedded/bin/openssl sha256
/opt/gitlab/embedded/bin/openssl rsa -noout -modulus -in /var/opt/gitlab/gitlab-rails/etc/gitlab-registry.key | /opt/gitlab/embedded/bin/openssl sha256
```

If the two pieces of the certificate do not align, remove the files and run `gitlab-ctl reconfigure`
to regenerate the pair. The pair is recreated using the existing values in `/etc/gitlab/gitlab-secrets.json` if they exist. To generate a new pair,
delete the `registry` section in your `/etc/gitlab/gitlab-secrets.json` before running `gitlab-ctl reconfigure`.

If you have overridden the automatically generated self-signed pair with
your own certificates and have made sure that their contents align, you can delete the 'registry'
section in your `/etc/gitlab/gitlab-secrets.json` and run `gitlab-ctl reconfigure`.

### AWS S3 with the GitLab registry error when pushing large images

When using AWS S3 with the GitLab registry, an error may occur when pushing
large images. Look in the Registry log for the following error:

```plaintext
level=error msg="response completed with error" err.code=unknown err.detail="unexpected EOF" err.message="unknown error"
```

To resolve the error specify a `chunksize` value in the Registry configuration.
Start with a value between `25000000` (25 MB) and `50000000` (50 MB).

**For Omnibus installations**

1. Edit `/etc/gitlab/gitlab.rb`:

   ```ruby
   registry['storage'] = {
     's3' => {
       'accesskey' => 'AKIAKIAKI',
       'secretkey' => 'secret123',
       'bucket'    => 'gitlab-registry-bucket-AKIAKIAKI',
       'chunksize' => 25000000
     }
   }
   ```

1. Save the file and [reconfigure GitLab](../restart_gitlab.md#omnibus-gitlab-reconfigure) for the changes to take effect.

**For installations from source**

1. Edit `config/gitlab.yml`:

   ```yaml
   storage:
     s3:
       accesskey: 'AKIAKIAKI'
       secretkey: 'secret123'
       bucket: 'gitlab-registry-bucket-AKIAKIAKI'
       chunksize: 25000000
   ```

1. Save the file and [restart GitLab](../restart_gitlab.md#installations-from-source) for the changes to take effect.

### Supporting older Docker clients

The Docker container registry shipped with GitLab disables the schema1 manifest
by default. If you are still using older Docker clients (1.9 or older), you may
experience an error pushing images. See
[omnibus-4145](https://gitlab.com/gitlab-org/omnibus-gitlab/-/issues/4145) for more details.

You can add a configuration option for backwards compatibility.

**For Omnibus installations**

1. Edit `/etc/gitlab/gitlab.rb`:

   ```ruby
   registry['compatibility_schema1_enabled'] = true
   ```

1. Save the file and [reconfigure GitLab](../restart_gitlab.md#omnibus-gitlab-reconfigure) for the changes to take effect.

**For installations from source**

1. Edit the YAML configuration file you created when you [deployed the registry](https://docs.docker.com/registry/deploying/). Add the following snippet:

   ```yaml
   compatibility:
       schema1:
           enabled: true
   ```

1. Restart the registry for the changes to take affect.

### Docker connection error

A Docker connection error can occur when there are special characters in either the group,
project or branch name. Special characters can include:

- Leading underscore
- Trailing hyphen/dash
- Double hyphen/dash

To get around this, you can [change the group path](../../user/group/manage.md#change-a-groups-path),
[change the project path](../../user/project/settings/index.md#rename-a-repository) or change the
branch name. Another option is to create a [push rule](../../user/project/repository/push_rules.md) to prevent
this at the instance level.

### Image push errors

When getting errors or "retrying" loops in an attempt to push an image but `docker login` works fine,
there is likely an issue with the headers forwarded to the registry by NGINX. The default recommended
NGINX configurations should handle this, but it might occur in custom setups where the SSL is
offloaded to a third party reverse proxy.

This problem was discussed in a [Docker project issue](https://github.com/docker/distribution/issues/970)
and a simple solution would be to enable relative URLs in the Registry.

**For Omnibus installations**

1. Edit `/etc/gitlab/gitlab.rb`:

   ```ruby
   registry['env'] = {
     "REGISTRY_HTTP_RELATIVEURLS" => true
   }
   ```

1. Save the file and [reconfigure GitLab](../restart_gitlab.md#omnibus-gitlab-reconfigure) for the changes to take effect.

**For installations from source**

1. Edit the YAML configuration file you created when you [deployed the registry](https://docs.docker.com/registry/deploying/). Add the following snippet:

   ```yaml
   http:
       relativeurls: true
   ```

1. Save the file and [restart GitLab](../restart_gitlab.md#installations-from-source) for the changes to take effect.

### Enable the Registry debug server

You can use the Container Registry debug server to diagnose problems. The debug endpoint can monitor metrics and health, as well as do profiling.

WARNING:
Sensitive information may be available from the debug endpoint.
Access to the debug endpoint must be locked down in a production environment.

The optional debug server can be enabled by setting the registry debug address
in your `gitlab.rb` configuration.

```ruby
registry['debug_addr'] = "localhost:5001"
```

After adding the setting, [reconfigure GitLab](../restart_gitlab.md#omnibus-gitlab-reconfigure) to apply the change.

Use curl to request debug output from the debug server:

```shell
curl "localhost:5001/debug/health"
curl "localhost:5001/debug/vars"
```

### Access old schema v1 Docker images

Support for the Docker registry API V1,
including [schema V1 image manifests](https://docs.docker.com/registry/spec/manifest-v2-1/),
was:

- [Deprecated in GitLab 13.7](https://about.gitlab.com/releases/2020/12/22/gitlab-13-7-released/#deprecate-pulls-that-use-v1-of-the-docker-registry-api)
- [Removed in GitLab 13.9](https://about.gitlab.com/releases/2021/02/22/gitlab-13-9-released/#deprecate-pulls-that-use-v1-of-the-docker-registry-api)

It's no longer possible to push or pull v1 images from the GitLab Container Registry.

If you had v1 images in the GitLab Container Registry, but you did not upgrade them (following the
[steps Docker recommends](https://docs.docker.com/registry/spec/deprecated-schema-v1/))
ahead of the GitLab 13.9 upgrade, these images are no longer accessible. If you try to pull them,
this error appears:

- `Error response from daemon: manifest invalid: Schema 1 manifest not supported`

For Self-Managed GitLab instances, you can regain access to these images by temporarily downgrading
the GitLab Container Registry to a version lower than `v3.0.0-gitlab`. Follow these steps to regain
access to these images:

1. Downgrade the Container Registry to [`v2.13.1-gitlab`](https://gitlab.com/gitlab-org/container-registry/-/releases/v2.13.1-gitlab).
1. Upgrade any v1 images.
1. Revert the Container Registry downgrade.

There's no need to put the registry in read-only mode during the image upgrade process. Ensure that
you are not relying on any new feature introduced since `v3.0.0-gitlab`. Such features are
unavailable during the upgrade process. See the [complete registry changelog](https://gitlab.com/gitlab-org/container-registry/-/blob/master/CHANGELOG.md)
for more information.

The following sections provide additional details about each installation method.

#### Helm chart installations

For Helm chart installations:

1. Override the [`image.tag`](https://docs.gitlab.com/charts/charts/registry/#configuration)
   configuration parameter with `v2.13.1-gitlab`.
1. Restart.
1. Performing the [images upgrade](#images-upgrade)) steps.
1. Revert the `image.tag` parameter to the previous value.

No other registry configuration changes are required.

#### Omnibus installations

For Omnibus installations:

1. Temporarily replace the registry binary that ships with GitLab 13.9+ for one prior to
   `v3.0.0-gitlab`. To do so, pull a previous version of the Docker image for the GitLab Container
   Registry, such as `v2.13.1-gitlab`. You can then grab the `registry` binary from within this
   image, located at `/bin/registry`:

   ```shell
   id=$(docker create registry.gitlab.com/gitlab-org/build/cng/gitlab-container-registry:v2.13.1-gitlab)
   docker cp $id:/bin/registry registry-2.13.1-gitlab
   docker rm $id
   ```

1. Replace the binary embedded in the Omnibus install, located at
   `/opt/gitlab/embedded/bin/registry`, with `registry-2.13.1-gitlab`. Make sure to start by backing
   up the original binary embedded in Omnibus, and restore it after performing the
   [image upgrade](#images-upgrade)) steps. You should [stop](https://docs.gitlab.com/omnibus/maintenance/#starting-and-stopping)
   the registry service before replacing its binary and start it right after. No registry
   configuration changes are required.

#### Source installations

For source installations, locate your `registry` binary and temporarily replace it with the one
obtained from `v3.0.0-gitlab`, as explained for [Omnibus installations](#omnibus-installations).
Make sure to start by backing up the original registry binary, and restore it after performing the
[images upgrade](#images-upgrade))
steps.

#### Images upgrade

Follow the [steps that Docker recommends to upgrade v1 images](https://docs.docker.com/registry/spec/deprecated-schema-v1/).
The most straightforward option is to pull those images and push them once again to the registry,
using a Docker client version above v1.12. Docker converts images automatically before pushing them
to the registry. Once done, all your v1 images should now be available as v2 images.

### Tags with an empty name

If using [AWS DataSync](https://aws.amazon.com/datasync/)
to copy the registry data to or between S3 buckets, an empty metadata object is created in the root
path of each container repository in the destination bucket. This causes the registry to interpret
such files as a tag that appears with no name in the GitLab UI and API. For more information, see
[this issue](https://gitlab.com/gitlab-org/container-registry/-/issues/341).

To fix this you can do one of two things:

- Use the AWS CLI [`rm`](https://awscli.amazonaws.com/v2/documentation/api/latest/reference/s3/rm.html)
  command to remove the empty objects from the root of **each** affected repository. Pay special
  attention to the trailing `/` and make sure **not** to use the `--recursive` option:

  ```shell
  aws s3 rm s3://<bucket>/docker/registry/v2/repositories/<path to repository>/
  ```

- Use the AWS CLI [`sync`](https://awscli.amazonaws.com/v2/documentation/api/latest/reference/s3/sync.html)
  command to copy the registry data to a new bucket and configure the registry to use it. This
  leaves the empty objects behind.

### Advanced Troubleshooting

We use a concrete example to illustrate how to
diagnose a problem with the S3 setup.

#### Investigate a cleanup policy

If you're unsure why your cleanup policy did or didn't delete a tag, execute the policy line by line
by running the below script from the [Rails console](../../administration/operations/rails_console.md).
This can help diagnose problems with the policy.

```ruby
repo = ContainerRepository.find(<project_id>)
policy = repo.project.container_expiration_policy

tags = repo.tags
tags.map(&:name)

tags.reject!(&:latest?)
tags.map(&:name)

regex_delete = ::Gitlab::UntrustedRegexp.new("\\A#{policy.name_regex}\\z")
regex_retain = ::Gitlab::UntrustedRegexp.new("\\A#{policy.name_regex_keep}\\z")

tags.select! { |tag| regex_delete.match?(tag.name) && !regex_retain.match?(tag.name) }

tags.map(&:name)

now = DateTime.current
tags.sort_by! { |tag| tag.created_at || now }.reverse! # Lengthy operation

tags = tags.drop(policy.keep_n)
tags.map(&:name)

older_than_timestamp = ChronicDuration.parse(policy.older_than).seconds.ago

tags.select! { |tag| tag.created_at && tag.created_at < older_than_timestamp }

tags.map(&:name)
```

- The script builds the list of tags to delete (`tags`).
- `tags.map(&:name)` prints a list of tags to remove. This may be a lengthy operation.
- After each filter, check the list of `tags` to see if it contains the intended tags to destroy.

#### Unexpected 403 error during push

A user attempted to enable an S3-backed Registry. The `docker login` step went
fine. However, when pushing an image, the output showed:

```plaintext
The push refers to a repository [s3-testing.myregistry.com:5050/root/docker-test/docker-image]
dc5e59c14160: Pushing [==================================================>] 14.85 kB
03c20c1a019a: Pushing [==================================================>] 2.048 kB
a08f14ef632e: Pushing [==================================================>] 2.048 kB
228950524c88: Pushing 2.048 kB
6a8ecde4cc03: Pushing [==>                                                ] 9.901 MB/205.7 MB
5f70bf18a086: Pushing 1.024 kB
737f40e80b7f: Waiting
82b57dbc5385: Waiting
19429b698a22: Waiting
9436069b92a3: Waiting
error parsing HTTP 403 response body: unexpected end of JSON input: ""
```

This error is ambiguous, as it's not clear whether the 403 is coming from the
GitLab Rails application, the Docker Registry, or something else. In this
case, since we know that since the login succeeded, we probably need to look
at the communication between the client and the Registry.

The REST API between the Docker client and Registry is described
[in the Docker documentation](https://docs.docker.com/registry/spec/api/). Usually, one would just
use Wireshark or tcpdump to capture the traffic and see where things went
wrong. However, since all communications between Docker clients and servers
are done over HTTPS, it's a bit difficult to decrypt the traffic quickly even
if you know the private key. What can we do instead?

One way would be to disable HTTPS by setting up an
[insecure Registry](https://docs.docker.com/registry/insecure/). This could introduce a
security hole and is only recommended for local testing. If you have a
production system and can't or don't want to do this, there is another way:
use mitmproxy, which stands for Man-in-the-Middle Proxy.

#### mitmproxy

[mitmproxy](https://mitmproxy.org/) allows you to place a proxy between your
client and server to inspect all traffic. One wrinkle is that your system
needs to trust the mitmproxy SSL certificates for this to work.

The following installation instructions assume you are running Ubuntu:

1. [Install mitmproxy](https://docs.mitmproxy.org/stable/overview-installation/).
1. Run `mitmproxy --port 9000` to generate its certificates.
   Enter <kbd>CTRL</kbd>-<kbd>C</kbd> to quit.
1. Install the certificate from `~/.mitmproxy` to your system:

   ```shell
   sudo cp ~/.mitmproxy/mitmproxy-ca-cert.pem /usr/local/share/ca-certificates/mitmproxy-ca-cert.crt
   sudo update-ca-certificates
   ```

If successful, the output should indicate that a certificate was added:

```shell
Updating certificates in /etc/ssl/certs... 1 added, 0 removed; done.
Running hooks in /etc/ca-certificates/update.d....done.
```

To verify that the certificates are properly installed, run:

```shell
mitmproxy --port 9000
```

This command runs mitmproxy on port `9000`. In another window, run:

```shell
curl --proxy "http://localhost:9000" "https://httpbin.org/status/200"
```

If everything is set up correctly, information is displayed on the mitmproxy window and
no errors are generated by the curl commands.

#### Running the Docker daemon with a proxy

For Docker to connect through a proxy, you must start the Docker daemon with the
proper environment variables. The easiest way is to shutdown Docker (for example `sudo initctl stop docker`)
and then run Docker by hand. As root, run:

```shell
export HTTP_PROXY="http://localhost:9000"
export HTTPS_PROXY="https://localhost:9000"
docker daemon --debug
```

This command launches the Docker daemon and proxies all connections through mitmproxy.

#### Running the Docker client

Now that we have mitmproxy and Docker running, we can attempt to sign in and
push a container image. You may need to run as root to do this. For example:

```shell
docker login s3-testing.myregistry.com:5050
docker push s3-testing.myregistry.com:5050/root/docker-test/docker-image
```

In the example above, we see the following trace on the mitmproxy window:

![mitmproxy output from Docker](img/mitmproxy-docker.png)

The above image shows:

- The initial PUT requests went through fine with a 201 status code.
- The 201 redirected the client to the S3 bucket.
- The HEAD request to the AWS bucket reported a 403 Unauthorized.

What does this mean? This strongly suggests that the S3 user does not have the right
[permissions to perform a HEAD request](https://docs.aws.amazon.com/AmazonS3/latest/API/API_HeadObject.html).
The solution: check the [IAM permissions again](https://docs.docker.com/registry/storage-drivers/s3/).
Once the right permissions were set, the error goes away.

### Missing `gitlab-registry.key` prevents container repository deletion

If you disable your GitLab instance's Container Registry and try to remove a project that has
container repositories, the following error occurs:

```plaintext
Errno::ENOENT: No such file or directory @ rb_sysopen - /var/opt/gitlab/gitlab-rails/etc/gitlab-registry.key
```

In this case, follow these steps:

1. Temporarily enable the instance-wide setting for the Container Registry in your `gitlab.rb`:

   ```ruby
   gitlab_rails['registry_enabled'] = true
   ```

1. Save the file and [reconfigure GitLab](../restart_gitlab.md#omnibus-gitlab-reconfigure)
   for the changes to take effect.
1. Try the removal again.

If you still can't remove the repository using the common methods, you can use the
[GitLab Rails console](../operations/rails_console.md)
to remove the project by force:

```ruby
# Path to the project you'd like to remove
prj = Project.find_by_full_path(<project_path>)

# The following will delete the project's container registry, so be sure to double-check the path beforehand!
if prj.has_container_registry_tags?
  prj.container_repositories.each { |p| p.destroy }
end
```