2022-03-16: Add PVCs to Alertmanager

Production Change

Change Summary

https://gitlab.com/gitlab-com/gl-infra/reliability/-/issues/15411

Alertmanager does not have state persistance, this change reconfigures Alertmanager STS to use a PVC for storage.

Change Details

  1. Services Impacted - ServiceAlertManager
  2. Change Technician - @f_santos
  3. Change Reviewer -
  4. Time tracking - unknown
  5. Downtime Component - none

Detailed steps for the change

Pre-Change Steps - steps to be completed before execution of the change

Estimated Time to Complete (mins) - 1

Change Steps - steps to take to execute the change

Estimated Time to Complete (mins) - 15

Post-Change Steps - steps to take to verify the change

Estimated Time to Complete (mins) - 10

  • Confirm STS was recreated k get sts -n monitoring
  • Confirm pods were rotated k get pod -n monitoring -l app=alertmanager
  • Confirm PVCs were created k get pvc -n monitoring
  • Confirm that silences are still configured

Rollback

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

Estimated Time to Complete (mins) - 10

Monitoring

Key metrics to observe

  • Metric: alertmanager_silences{state='active'}
    • Location: Thanos
    • What changes to this metric should prompt a rollback: Number of active silences == 0

Summary of infrastructure changes

  • Does this change introduce new compute instances?
  • Does this change re-size any existing compute instances?
  • Does this change introduce any additional usage of tooling like Elastic Search, CDNs, Cloudflare, etc?

Summary of the above

Change Reviewer checklist

C4 C3 C2 C1:

  • 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:

  • 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.

Change Technician checklist

  • This issue has a criticality label (e.g. C1, C2, C3, C4) and a change-type label (e.g. changeunscheduled, changescheduled) based on the Change Management Criticalities.
  • This issue has the change technician as the assignee.
  • Pre-Change, Change, Post-Change, and Rollback steps and have been filled out and reviewed.
  • This Change Issue is linked to the appropriate Issue and/or Epic
  • Necessary approvals have been completed based on the Change Management Workflow.
  • 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.
  • 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.)
  • 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.
Edited by Filipe Santos