Add docs for request profilingfix/request-profiler-docs

Closes #23239

6 files changed, 20 insertions, 1 deletions

diff --git a/CHANGELOG b/CHANGELOG
index d2f1501bd2a..9def97ca342 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -115,6 +115,7 @@ v 8.13.0 (unreleased)
   - Fixes padding in all clipboard icons that have .btn class
   - Fix a typo in doc/api/labels.md
   - API: all unknown routing will be handled with 404 Not Found
+  - Add docs for request profiling
   - Make guests unable to view MRs on private projects
 
 v 8.12.7
diff --git a/doc/README.md b/doc/README.md
index 7e3d9b00900..c30bf328003 100644
--- a/doc/README.md
+++ b/doc/README.md
@@ -49,6 +49,7 @@
 - [Git LFS configuration](workflow/lfs/lfs_administration.md)
 - [Housekeeping](administration/housekeeping.md) Keep your Git repository tidy and fast.
 - [GitLab Performance Monitoring](administration/monitoring/performance/introduction.md) Configure GitLab and InfluxDB for measuring performance metrics.
+- [Request Profiling](administration/monitoring/performance/request_profiling.md) Get a detailed profile on slow requests.
 - [Monitoring uptime](user/admin_area/monitoring/health_check.md) Check the server status using the health check endpoint.
 - [Debugging Tips](administration/troubleshooting/debug.md) Tips to debug problems when things go wrong
 - [Sidekiq Troubleshooting](administration/troubleshooting/sidekiq.md) Debug when Sidekiq appears hung and is not processing jobs.
diff --git a/doc/administration/monitoring/performance/img/request_profile_result.png b/doc/administration/monitoring/performance/img/request_profile_result.png
new file mode 100644
index 00000000000..73e2fdcab67
--- /dev/null
+++ b/doc/administration/monitoring/performance/img/request_profile_result.png
diff --git a/doc/administration/monitoring/performance/img/request_profiling_token.png b/doc/administration/monitoring/performance/img/request_profiling_token.png
new file mode 100644
index 00000000000..04d87567816
--- /dev/null
+++ b/doc/administration/monitoring/performance/img/request_profiling_token.png
diff --git a/doc/administration/monitoring/performance/request_profiling.md b/doc/administration/monitoring/performance/request_profiling.md
new file mode 100644
index 00000000000..c358dfbead2
--- /dev/null
+++ b/doc/administration/monitoring/performance/request_profiling.md
@@ -0,0 +1,16 @@
+# Request Profiling
+
+## Procedure
+1. Grab the profiling token from `Monitoring > Requests Profiles` admin page
+(highlighted in a blue in the image below).
+![Profile token](img/request_profiling_token.png)
+1. Pass the header `X-Profile-Token: <token>` to the request you want to profile. You can use any of these tools
+    * [ModHeader](https://chrome.google.com/webstore/detail/modheader/idgpnmonknjnojddfkpgkljpfnnfcklj) Chrome extension
+    * [Modify Headers](https://addons.mozilla.org/en-US/firefox/addon/modify-headers/) Firefox extension
+    * `curl --header 'X-Profile-Token: <token>' https://gitlab.example.com/group/project`
+1. Once request is finished (which will take a little longer than usual), you can
+view the profiling output from `Monitoring > Requests Profiles` admin page.
+![Profiling output](img/request_profile_result.png)
+
+## Cleaning up
+Profiling output will be cleared out every day via a Sidekiq worker.
diff --git a/doc/development/performance.md b/doc/development/performance.md
index 7ff603e2c4a..65d34829025 100644
--- a/doc/development/performance.md
+++ b/doc/development/performance.md
@@ -34,10 +34,11 @@ graphs/dashboards.
 
 ## Tooling
 
-GitLab provides two built-in tools to aid the process of improving performance:
+GitLab provides built-in tools to aid the process of improving performance:
 
 * [Sherlock](profiling.md#sherlock)
 * [GitLab Performance Monitoring](../monitoring/performance/monitoring.md)
+* [Request Profiling](../administration/monitoring/performance/request_profiling.md)
 
 GitLab employees can use GitLab.com's performance monitoring systems located at
 <http://performance.gitlab.net>, this requires you to log in using your