2023-04-13: [GSTG]-Provision-main-v14 cluster

Production Change

Change Summary

It is a requirement to provision a new database cluster to migrate the current main db to version PG14.

This change request add's the patroni-main-v14 module of PG14 in main.tf needed for the upgrade.

Change Details

1. Services Impacted - ServicePatroni ServicePgbouncer
2. Change Technician - @anganga
3. Change Reviewer - @rehab
4. Time tracking - 60 minutes
5. Downtime Component - none

Detailed steps for the change

Change Steps - steps to take to execute the change

Estimated Time to Complete (mins) - 60 minutes

• Set label changein-progress /label ~change::in-progress
• Merge the following MRs
  • https://ops.gitlab.net/gitlab-com/gl-infra/config-mgmt/-/merge_requests/5469
  • https://gitlab.com/gitlab-com/gl-infra/chef-repo/-/merge_requests/3196
• Execute the db-migration/pg-replica-rebuild Ansible playbook from your Tmux session to Initialize the whole cluster.
  • To initialize the whole cluster, including the Standby Leader, run the rebuild-all.yml playbook:
    • Create an inventory file in db-migration/pg-replica-rebuild/inventory db-migration!377 (merged)
    • execute ansible-playbook -i inventory/patroni-main-v14-gstg.yml rebuild-all.yml
• 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) - 20 minutes

• Revert https://ops.gitlab.net/gitlab-com/gl-infra/config-mgmt/-/merge_requests/5469
• Set label changeaborted /label ~change::aborted

Monitoring

Key metrics to observe

• Metric: patroni Service Error Ratio and pgbouncer SLI Error Ratio
  • Location: https://dashboards.gitlab.net/goto/RKW3kRPVz?orgId=1
  • What changes to this metric should prompt a rollback: elevated error rates for pgbouncer

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.