2023-02-03: Thanos compactor migration

Production Change

Change Summary

This change is for migrating the thanos compactor component out of GCP VM instances and into kubernetes.
Repeated for the following machines/envs:

thanos-compact-01-inf-ops.c.gitlab-ops.internal
thanos-compact-01-inf-gprd.c.gitlab-production.internal
thanos-compact-01-inf-gstg.c.gitlab-staging-1.internal
thanos-compact-01-inf-pre.c.gitlab-pre.internal

Change Details

  1. Services Impacted - ServiceThanos
  2. Change Technician - @cindy
  3. Change Reviewer - @nduff
  4. Time tracking - unknown
  5. Downtime Component - none

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

  • Set label changein-progress /label ~change::in-progress
  • Disable chef on the VM chef-client-disable "https://gitlab.com/gitlab-com/gl-infra/production/-/issues/8303"
  • Stop the compactor service systemctl stop thanos-compact
  • Enable the compactor service in gitlab-helmfiles.
thanos:
  compactor:
    enabled: true

Example MR

  • Validate compactor service is running without issues in kubernetes ops cluster.
  • Repeat per environment VM:
    • thanos-compact-01-inf-pre.c.gitlab-pre.internal
    • thanos-compact-01-inf-gstg.c.gitlab-staging-1.internal
    • thanos-compact-01-inf-ops.c.gitlab-ops.internal
    • thanos-compact-01-inf-gprd.c.gitlab-production.internal
  • Set label changecomplete /label ~change::complete

Cleanup

  • Destroy VMs.
  • Remove traces from chef.

Rollback

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

Estimated Time to Complete (mins) - 15

  • Disable compactor service in gitlab-helmfiles by reverting the MR.
  • Re-enable VM systemd service systemctl start thanos-compact.
  • Repeat as necessary per env VM:
    • thanos-compact-01-inf-pre.c.gitlab-pre.internal
    • thanos-compact-01-inf-gstg.c.gitlab-staging-1.internal
    • thanos-compact-01-inf-ops.c.gitlab-ops.internal
    • thanos-compact-01-inf-gprd.c.gitlab-production.internal
  • Set label changeaborted /label ~change::aborted

Monitoring

Key metrics to observe

Note: The compactor component of thanos can be down for reasonable periods of time.
In the even of issues during migration, first determine if they can be resolved in kubernetes prior to executing a rollback operation.

  • Metric: Thanos compactor halted

    • Location: Thanos query.
    • What changes to this metric should prompt a rollback: If the compactor is showing as halted (1) and we are unable to remediate or determine the cause in a timely manner.

  • Metric: Thanos is progressing compactions/downsamples/deletions.

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 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 (If needed! Cases include DB change) prior to 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 Nick Duff