[GPRD] Prepare for: Execute logical replication and upgrade test in the main production cluster, add missing node

Production Change

Change Summary

In order to execute #8611 (closed), we need to add another node to our test cluster, prior to the test, so it is able to catch up.

Change Details

1. Services Impacted - Database
2. Change Technician - @alexander-sosna
3. Change Reviewer - @bshah11
4. Time tracking - 4 hours
5. Downtime Component - 0

Detailed steps for the change

Change Steps - steps to take to execute the change

Estimated Time to Complete (mins) - 2hs to 4hs

• Set label changein-progress /label ~change::in-progress
• Merge https://ops.gitlab.net/gitlab-com/gl-infra/config-mgmt/-/merge_requests/5383
• Run matching pipelines to apply the change https://ops.gitlab.net/gitlab-com/gl-infra/config-mgmt/-/pipelines
• Verify the host is created, ping patroni-main-logical-pg13-02-db-gprd.c.gitlab-production.internal
• Verify the host is provisioned by Chef ssh patroni-main-logical-pg13-02-db-gprd.c.gitlab-production.internal
• Silence alerts on patroni-main-logical-pg13-02-db-gprd.c.gitlab-production.internal for the next 2 weeks here https://alerts.gitlab.net/#/silences/new, equal to https://alerts.gitlab.net/#/silences/6bc72e74-8096-48b5-83ab-bce3ea28a7cd.
• Follow steps to create a new replica node as documented at https://gitlab.com/gitlab-com/runbooks/-/blob/master/docs/patroni-ci/rebuild_ci_cluster_from_prod.md#create-the-patroni-ci-standby-cluster-instances
  • cd db-migration/pg-replica-rebuild
  • ansible-playbook -i inventory/gprd-main-logical.yml rebuild-replicas.yml --limit 'patroni-main-logical-pg13-02-db-gprd*'
• Verify the host hast started to catch up, execute on patroni-main-logical-pg13-01 in psql: gitlabhq_production=# SELECT * FROM pg_stat_replication; and check that patroni-main-logical-pg13-02 is replicating.
• 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) - 15 minutes

• Revert https://ops.gitlab.net/gitlab-com/gl-infra/config-mgmt/-/merge_requests/5383
• Run matching pipelines to apply the change https://ops.gitlab.net/gitlab-com/gl-infra/config-mgmt/-/pipelines
• Set label changeaborted /label ~change::aborted

Monitoring

Key metrics to observe

Key metrics to observe

• Metric patroni Service Apdex: https://dashboards.gitlab.net/d/patroni-main/patroni-overview?orgId=1
• Metric CPU utilization: https://dashboards.gitlab.net/d/000000144/postgresql-overview?orgId=1&from=now-6h&to=now&viewPanel=13
• Metric for database load: https://dashboards.gitlab.net/d/000000144/postgresql-overview?orgId=1&from=now-3h&to=now&viewPanel=9&var-prometheus=Global&var-environment=gprd&var-type=patroni

• Metric: Disk utilization
  • Location: https://dashboards.gitlab.net/d/000000144/postgresql-overview?orgId=1&viewPanel=10&var-prometheus=Global&var-environment=gprd&var-type=patroni
  • What changes to this metric should prompt a rollback: If we start to allocate more disk linearly we need to rollback.

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.