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2023-12-14: Enable running ClickHouse migrations during deploy

Production Change

Change Summary

In Run ClickHouse migrations during gitlab:db:conf... (gitlab-org/gitlab!138661 - merged) we introduced running ClickHouse migrations during the gitlab:db:configure which is run during the normal deploy.

It's behind the run_clickhouse_migrations_automatically feature flag, so we only need to enable the FF and see that the deployment succeeds.

Since in theory enabling such feature flag can block/fail production deployments, I decided to create a change-management issue.

Note about locks/sidekiq workers: when we initiate ClickHouse migration we:

  1. acquire an exclusive lock for running migrations
  2. pause ClickHouse background sync workers queue
  3. wait till existing ClickHouse background sync workers finish their job
  4. run migrations
  5. unpause workers

There're 2 more feature flags:

  • wait_for_clickhouse_workers_during_migration
  • pause_clickhouse_workers_during_migration

Making it a total of 3 feature flags:

FF name meaning enabled on production before this change is executed
run_clickhouse_migrations_automatically Run or not CH migration together with gitlab:db:configure - disable this in case of migrations failure and redeploy - [ ]
wait_for_clickhouse_workers_during_migration Waiting for existing workers to finish - try disabling this if migration step is blocked for too long - [x]
pause_clickhouse_workers_during_migration Pausing workers to avoid conflicts try disabling this is ClickHouse workers pile in the paused queue - [x]

Change Details

  1. Services Impacted - ServiceDeploy-Node ServiceDeployTooling
  2. Change Technician - @vshushlin
  3. Change Reviewer -
  4. Time tracking - unknown
  5. Downtime Component - none

Set Maintenance Mode in GitLab

If your change involves scheduled maintenance, add a step to set and unset maintenance mode per our runbooks. This will make sure SLA calculations adjust for the maintenance period.

Detailed steps for the change

Change Steps - steps to take to execute the change

Estimated Time to Complete (mins) - Estimated Time to Complete in Minutes

  • All of the steps below should first be done on staging.

  • Set label changein-progress /label ~change::in-progress

  • Execute /chatops run feature set run_clickhouse_migrations_automatically true

  • Wait for the deploy to finish and check the deploy logs

  • Go to the rails console and execute this:

    ::ClickHouse::Client.select("SELECT * from schema_migrations", :main)

    It should return something like:

    => [{"version"=>"20230705124511", "active"=>1, "applied_at"=>Mon, 11 Dec 2023 15:57:11.750000000 UTC +00:00},
 {"version"=>"20230707151359", "active"=>1, "applied_at"=>Mon, 11 Dec 2023 15:57:11.876000000 UTC +00:00},
 {"version"=>"20230719101806", "active"=>1, "applied_at"=>Mon, 11 Dec 2023 15:57:11.995000000 UTC +00:00},
 {"version"=>"20230724064832", "active"=>1, "applied_at"=>Mon, 11 Dec 2023 15:57:12.117000000 UTC +00:00},
 {"version"=>"20230724064918", "active"=>1, "applied_at"=>Mon, 11 Dec 2023 15:57:12.236000000 UTC +00:00},
 {"version"=>"20230808070520", "active"=>1, "applied_at"=>Mon, 11 Dec 2023 15:57:12.350000000 UTC +00:00},
 {"version"=>"20230808140217", "active"=>1, "applied_at"=>Mon, 11 Dec 2023 15:57:12.470000000 UTC +00:00},
 {"version"=>"20231106202300", "active"=>1, "applied_at"=>Mon, 11 Dec 2023 15:57:12.605000000 UTC +00:00},
 {"version"=>"20231114142100", "active"=>1, "applied_at"=>Mon, 11 Dec 2023 15:57:12.765000000 UTC +00:00},
 {"version"=>"20231129062064", "active"=>1, "applied_at"=>Mon, 11 Dec 2023 15:57:12.871000000 UTC +00:00},
 {"version"=>"20231129062151", "active"=>1, "applied_at"=>Mon, 11 Dec 2023 15:57:12.985000000 UTC +00:00},
 {"version"=>"20231205104100", "active"=>1, "applied_at"=>Mon, 11 Dec 2023 15:57:13.096000000 UTC +00:00},
 {"version"=>"20231205104101", "active"=>0, "applied_at"=>Mon, 11 Dec 2023 15:58:21.214000000 UTC +00:00},
 {"version"=>"20231205112200", "active"=>0, "applied_at"=>Mon, 11 Dec 2023 15:58:21.096000000 UTC +00:00}]

  • Set label changecomplete /label ~change::complete

Rollback

Rollback steps - steps to be taken in the event of a need to rollback this change

Estimated Time to Complete (mins) - Estimated Time to Complete in Minutes

  • Execute /chatops run feature set run_clickhouse_migrations_automatically false
  • Set label changeaborted /label ~change::aborted

Monitoring

Look at the deploy logs first: specifically for Running gitlab:clickhouse:migrate:main rake task line. It should print something like this:

Running gitlab:clickhouse:migrate:main rake task
== 20230705124511 CreateEvents: migrating =====================================
== 20230705124511 CreateEvents: migrated (0.0203s) ============================

== 20230707151359 CreateCiFinishedBuilds: migrating ===========================
== 20230707151359 CreateCiFinishedBuilds: migrated (0.0148s) ==================

== 20230719101806 CreateCiFinishedBuildsAggregatedQueueingDelayPercentiles: migrating
== 20230719101806 CreateCiFinishedBuildsAggregatedQueueingDelayPercentiles: migrated (0.0114s)

== 20230724064832 CreateContributionAnalyticsEvents: migrating ================
== 20230724064832 CreateContributionAnalyticsEvents: migrated (0.0150s) =======

Key metrics to observe

  • Metric: Deploy status
    • Location: No idea
    • What changes to this metric should prompt a rollback: Failed deploy

Change Reviewer checklist

C4 C3 C2 C1:

  • Check if the following applies:
    • The scheduled day and time of execution of the change is appropriate.
    • The change plan is technically accurate.
    • The change plan includes estimated timing values based on previous testing.
    • The change plan includes a viable rollback plan.
    • The specified metrics/monitoring dashboards provide sufficient visibility for the change.

C2 C1:

  • Check if the following applies:
    • The complexity of the plan is appropriate for the corresponding risk of the change. (i.e. the plan contains clear details).
    • The change plan includes success measures for all steps/milestones during the execution.
    • The change adequately minimizes risk within the environment/service.
    • The performance implications of executing the change are well-understood and documented.
    • The specified metrics/monitoring dashboards provide sufficient visibility for the change.
      • If not, is it possible (or necessary) to make changes to observability platforms for added visibility?
    • The change has a primary and secondary SRE with knowledge of the details available during the change window.
    • The change window has been agreed with Release Managers in advance of the change. If the change is planned for APAC hours, this issue has an agreed pre-change approval.
    • The labels blocks deployments and/or blocks feature-flags are applied as necessary.

Change Technician checklist

  • Check if all items below are complete:
    • The change plan is technically accurate.
    • This Change Issue is linked to the appropriate Issue and/or Epic
    • Change has been tested in staging and results noted in a comment on this issue.
    • A dry-run has been conducted and results noted in a comment on this issue.
    • The change execution window respects the Production Change Lock periods.
    • For C1 and C2 change issues, the change event is added to the GitLab Production calendar.
    • For C1 and C2 change issues, the SRE on-call has been informed prior to change being rolled out. (In #production channel, mention @sre-oncall and this issue and await their acknowledgement.)
    • For C1 and C2 change issues, the SRE on-call provided approval with the eoc_approved label on the issue.
    • For C1 and C2 change issues, the Infrastructure Manager provided approval with the manager_approved label on the issue.
    • Release managers have been informed prior to any C1, C2, or blocks deployments change being rolled out. (In #production channel, mention @release-managers and this issue and await their acknowledgment.)
    • There are currently no active incidents that are severity1 or severity2
    • If the change involves doing maintenance on a database host, an appropriate silence targeting the host(s) should be added for the duration of the change.
Edited by Vladimir Shushlin