Support pluggable custodian monitorpluggable-custodian-monitor

Enable build time configurable monitor for custodian and remove custom
sensu events.

6 files changed, 148 insertions, 45 deletions

diff --git a/src/custodian/rebar.config.script b/src/custodian/rebar.config.script
new file mode 100644
index 000000000..f32db974c
--- /dev/null
+++ b/src/custodian/rebar.config.script
@@ -0,0 +1,35 @@
+% Licensed under the Apache License, Version 2.0 (the "License"); you may not
+% use this file except in compliance with the License. You may obtain a copy of
+% the License at
+%
+%   http://www.apache.org/licenses/LICENSE-2.0
+%
+% Unless required by applicable law or agreed to in writing, software
+% distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+% WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+% License for the specific language governing permissions and limitations under
+% the License.
+
+
+CouchConfig = case filelib:is_file(os:getenv("COUCHDB_CONFIG")) of
+    true ->
+        {ok, Result} = file:consult(os:getenv("COUCHDB_CONFIG")),
+        Result;
+    false ->
+        []
+end,
+
+CustodianMonitor = case lists:keyfind(custodian_monitor, 1, CouchConfig) of
+    {custodian_monitor, Module} when Module /= "" ->
+        list_to_atom(Module);
+    _ ->
+        custodian_noop_monitor
+end,
+
+CurrentOpts = case lists:keyfind(erl_opts, 1, CONFIG) of
+    {erl_opts, Opts} -> Opts;
+    false -> []
+end,
+
+CustodianOpts = {d, 'CUSTODIAN_MONITOR', CustodianMonitor},
+lists:keystore(erl_opts, 1, CONFIG, {erl_opts, [CustodianOpts | CurrentOpts]}).
diff --git a/src/custodian/src/custodian.app.src.script b/src/custodian/src/custodian.app.src.script
new file mode 100644
index 000000000..551b9c2c3
--- /dev/null
+++ b/src/custodian/src/custodian.app.src.script
@@ -0,0 +1,48 @@
+% Licensed under the Apache License, Version 2.0 (the "License"); you may not
+% use this file except in compliance with the License. You may obtain a copy of
+% the License at
+%
+%   http://www.apache.org/licenses/LICENSE-2.0
+%
+% Unless required by applicable law or agreed to in writing, software
+% distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+% WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+% License for the specific language governing permissions and limitations under
+% the License.
+
+CouchConfig = case filelib:is_file(os:getenv("COUCHDB_CONFIG")) of
+    true ->
+        {ok, Result} = file:consult(os:getenv("COUCHDB_CONFIG")),
+        Result;
+    false ->
+        []
+end.
+
+CustodianMonitorApp = case lists:keyfind(custodian_monitor_app, 1, CouchConfig) of
+    {custodian_monitor_app, AppName} when AppName /= "" ->
+        [list_to_atom(AppName)];
+    _ ->
+        []
+end.
+
+BaseApplications = [
+    kernel,
+    stdlib,
+    couch_log,
+    config,
+    couch_event,
+    couch,
+    mem3
+].
+
+Applications = CustodianMonitorApp ++ BaseApplications.
+
+{application, custodian,
+ [
+  {description, "in your cluster, looking after your stuff"},
+  {vsn, git},
+  {registered, []},
+  {applications, Applications},
+  {mod, { custodian_app, []}},
+  {env, []}
+ ]}.
diff --git a/src/custodian/src/custodian_db_checker.erl b/src/custodian/src/custodian_db_checker.erl
index 8308c8ecb..10502dd76 100644
--- a/src/custodian/src/custodian_db_checker.erl
+++ b/src/custodian/src/custodian_db_checker.erl
@@ -149,17 +149,9 @@ get_stats_db() ->
 
 send_missing_db_alert(DbName) ->
     couch_log:notice("Missing system database ~s", [DbName]),
-    Command = [
-        "send-sensu-event --standalone --critical",
-        " --output=\"Missing system database ",
-        binary_to_list(DbName),
-        "\" --handler=default custodian-missing-db-check"],
-    os:cmd(lists:concat(Command)).
+    ?CUSTODIAN_MONITOR:send_missing_db_alert(DbName).
+
 
 clear_missing_dbs_alert() ->
     couch_log:notice("All system databases exist.", []),
-    Command = [
-        "send-sensu-event --standalone --ok",
-        " --output=\"All system databases exist\"",
-        " --handler=default custodian-missing-db-check"],
-    os:cmd(lists:concat(Command)).
+    ?CUSTODIAN_MONITOR:clear_missing_dbs_alert().
diff --git a/src/custodian/src/custodian.app.src b/src/custodian/src/custodian_monitor.erl
index b93b21ebb..3cca046ed 100644
--- a/src/custodian/src/custodian.app.src
+++ b/src/custodian/src/custodian_monitor.erl
@@ -10,20 +10,19 @@
 % License for the specific language governing permissions and limitations under
 % the License.
 
-{application, custodian,
- [
-  {description, "in your cluster, looking after your stuff"},
-  {vsn, git},
-  {registered, []},
-  {applications, [
-                  kernel,
-                  stdlib,
-                  couch_log,
-                  config,
-                  couch_event,
-                  couch,
-                  mem3
-                 ]},
-  {mod, { custodian_app, []}},
-  {env, []}
- ]}.
+-module(custodian_monitor).
+
+
+% N.B. that callback return values are ignored
+
+-callback send_missing_db_alert(DbName :: binary()) ->
+    Ignored :: any().
+
+
+-callback clear_missing_dbs_alert() ->
+    Ignored :: any().
+
+
+-callback send_event(
+    Name :: string(), Count :: non_neg_integer(), Description :: string()) ->
+    Ignored :: any().
diff --git a/src/custodian/src/custodian_noop_monitor.erl b/src/custodian/src/custodian_noop_monitor.erl
new file mode 100644
index 000000000..5c793aeca
--- /dev/null
+++ b/src/custodian/src/custodian_noop_monitor.erl
@@ -0,0 +1,35 @@
+% Licensed under the Apache License, Version 2.0 (the "License"); you may not
+% use this file except in compliance with the License. You may obtain a copy of
+% the License at
+%
+%   http://www.apache.org/licenses/LICENSE-2.0
+%
+% Unless required by applicable law or agreed to in writing, software
+% distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+% WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+% License for the specific language governing permissions and limitations under
+% the License.
+
+-module(custodian_noop_monitor).
+
+
+-behaviour(custodian_monitor).
+
+
+-export([
+    send_missing_db_alert/1,
+    clear_missing_dbs_alert/0,
+    send_event/3
+]).
+
+
+send_missing_db_alert(_DbName) ->
+    false.
+
+
+clear_missing_dbs_alert() ->
+    false.
+
+
+send_event(_Name, _Count, _Description) ->
+    false.
diff --git a/src/custodian/src/custodian_server.erl b/src/custodian/src/custodian_server.erl
index 322cc3264..0a21eed23 100644
--- a/src/custodian/src/custodian_server.erl
+++ b/src/custodian/src/custodian_server.erl
@@ -143,28 +143,22 @@ handle_db_event(_DbName, _Event, _St) ->
     {ok, nil}.
 
 check_shards() ->
-    [send_sensu_event(Item) || Item <- custodian:summary()].
+    [send_event(Item) || Item <- custodian:summary()].
 
-send_sensu_event({_, Count} = Item) ->
-    Level = case Count of
+
+send_event({_, Count} = Item) ->
+    Description = describe(Item),
+    Name = check_name(Item),
+    case Count of
         0 ->
-            "--ok";
+            ok;
         1 ->
-            couch_log:critical("~s", [describe(Item)]),
-            "--critical";
+            couch_log:critical("~s", [Description]);
         _ ->
-            couch_log:warning("~s", [describe(Item)]),
-            "--warning"
+            couch_log:warning("~s", [Description])
     end,
-    Cmd = lists:concat([
-        "send-sensu-event --standalone ",
-        Level,
-        " --output=\"",
-        describe(Item),
-        "\" ",
-        check_name(Item)
-    ]),
-    os:cmd(Cmd).
+    ?CUSTODIAN_MONITOR:send_event(Name, Count, Description).
+
 
 describe({{safe, N}, Count}) ->
     lists:concat([Count, " ", shards(Count), " in cluster with only ", N,