2024-04-18: Record all running builds instead of only ones running in shared runners

Production Change

Change Summary

This change relates to the deployment of gitlab-org/gitlab#452166 (closed). It will cause to all running builds to be logged to the ci_running_builds table. Currently, only builds running on instance (shared) runners are logged. Therefore, the number of records being inserted is expected to grow by a factor of 4-5 times.

Looking at the production database, we're creating 1.1M records on a typical day. With this change, that will increase to almost 5M.

Source - ClickHouse

SELECT toStartOfInterval (started_at, INTERVAL 1 DAY) AS day, runner_type, COUNT(*)
FROM "ci_finished_builds" FINAL
WHERE ci_finished_builds.started_at >= '2024-04-03' AND ci_finished_builds.started_at < '2024-04-10'
GROUP BY day, runner_type
ORDER BY day DESC, runner_type;

Change Details

Services Impacted - Postgres
Change Technician - @pedropombeiro
Change Reviewer - @mayra-cabrera
Time tracking - unknown
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) - 360 minutes

Rollback

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

Estimated Time to Complete (mins) - (5 minutes to disable add_all_ci_running_builds FF, 240 minutes to disable remove_all_ci_running_builds FF)

Disable the add_all_ci_running_builds FF.
Wait until the non-shared runner builds have completed and been drained from the table.
Disable the remove_all_ci_running_builds FF.
Set label changeaborted /label ~change::aborted

Monitoring

Key metrics to observe

Metric: pgbouncer saturation/error ratio
- Location: https://dashboards.gitlab.net/d/pgbouncer-main/pgbouncer3a-overview?orgId=1&from=now-24h&to=now
- What changes to this metric should prompt a rollback:
  - pgbouncer saturation reaching a level 20% above the level from 24h ago.
  - pgbouncer service error ratio sensibly increasing.
Metric: rails_primary_sql SLI RPS - Requests per Second
- Location: https://dashboards.gitlab.net/d/patroni-ci-main/patroni-ci3a-overview?orgId=1&from=now-24h&to=now
- What changes to this metric should prompt a rollback:
  - Given that we'll be writting 4-5x times more to the ci_running_builds table, we expect an increase in RPS to the primary node. If this increases more than 10% compared to the previous week, we should consider rolling the change back.

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 Apr 19, 2024 by Pedro Pombeiro