Rake task to ensure metrics from deployed environments

doc/administration/raketasks/maintenance.md

@@ -270,3 +270,15 @@ database: gitlabhq_production
 --------------------------------------------------
    up     migration_id    migration_name
 ```
+
+## Import common metrics
+
+Sometimes you may need to re-import the common metrics that power the Metrics dashboards.
+
+This could be as a result of [updating existing metrics](../../development/prometheus_metrics.md#update-existing-metrics), or as a [troubleshooting measure](../../user/project/integrations/prometheus.md#troubleshooting).
+
+To re-import the metrics you can run:
+
+```sh
+sudo gitlab-rake metrics:setup_common_metrics
+```

doc/development/prometheus_metrics.md

@@ -22,7 +22,9 @@ The requirement for adding a new metric is to make each query to have an unique
 
 ### Update existing metrics
 
-After you add or change existing _common_ metric you have to create a new database migration that will query and update all existing metrics.
+After you add or change an existing common metric, you must [re-run the import script](../administration/raketasks/maintenance.md#import-common-metrics) that will query and update all existing metrics.
+
+Or, you can create a database migration:
 
 NOTE: **Note:**
 If a query metric (which is identified by `id:`) is removed it will not be removed from database by default.

doc/user/project/integrations/prometheus.md

@@ -574,6 +574,7 @@ If the "No data found" screen continues to appear, it could be due to:
   are not labeled correctly. To test this, connect to the Prometheus server and
   [run a query](prometheus_library/kubernetes.html#metrics-supported), replacing `$CI_ENVIRONMENT_SLUG`
   with the name of your environment.
+- You may need to re-add the GitLab predefined common metrics. This can be done by running the [import common metrics rake task](../../../administration/raketasks/maintenance.md#import-common-metrics).
 
 [autodeploy]: ../../../topics/autodevops/index.md#auto-deploy
 [kubernetes]: https://kubernetes.io

lib/tasks/gitlab/metrics.rake

+# frozen_string_literal: true
+
+namespace :metrics do
+  desc "GitLab | Setup common metrics"
+  task setup_common_metrics: :gitlab_environment do
+    ::Gitlab::DatabaseImporters::CommonMetrics::Importer.new.execute
+  end
+end