Upgrade redis-cache on gstg to 6.2

Production Change

Change Summary

We are upgrading Redis to 6.2 in order to have version parity for the Kubernetes migration. This CR aims to upgrade the cache Redis instance from 6.0.14 to 6.2.6.

Closes scalability#1567

This CR is based on #6287 (closed)

Change Details

1. Services Impacted - ServiceRedis
2. Change Technician - @alejandro
3. Change Reviewer -
4. Time tracking - 1h
5. Downtime Component - Some writes will be lost during failover. Reads remain available.

Detailed steps for the change

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

Estimated Time to Complete (mins) - 5 minutes

• Set label changein-progress on this issue
• Merge and apply chef change
• Prepare shell

  cd runbooks

Change Steps - steps to take to execute the change

Estimated Time to Complete (mins) - 30 mins

• Get original version (expect 6.0.14)

  parallel --tag -k ssh redis-cache-{}-db-gstg.c.gitlab-staging-1.internal 'sudo gitlab-redis-cli info | grep ^redis_version' ::: 01 02 03
  parallel --tag -k ssh redis-cache-sentinel-{}-db-gstg.c.gitlab-staging-1.internal '/opt/gitlab/embedded/bin/redis-cli -p 26379 info | grep ^redis_version' ::: 01 02 03

• Run reconfigure script

  scripts/redis-reconfigure.sh gstg redis-cache

• Get new version (expect 6.2.6)

  parallel --tag ssh redis-cache-{}-db-gstg.c.gitlab-staging-1.internal 'sudo gitlab-redis-cli info | grep ^redis_version' ::: 01 02 03

Rollback

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

Estimated Time to Complete (mins) - 30 mins

• Revert and apply chef change
• Get original version (expect 6.2.6)

  parallel --tag -k ssh redis-cache-{}-db-gstg.c.gitlab-staging-1.internal 'sudo gitlab-redis-cli info | grep ^redis_version' ::: 01 02 03

• Run reconfigure script

  scripts/redis-reconfigure.sh gstg redis-cache

• Get new version (expect 6.0.14)

  parallel --tag ssh redis-cache-{}-db-gstg.c.gitlab-staging-1.internal 'sudo gitlab-redis-cli info | grep ^redis_version' ::: 01 02 03

Monitoring

Key metrics to observe

• Metric: Saturation redis_primary_cpu
  • Location: https://dashboards.gitlab.net/d/redis-cache-main/redis-cache-overview?orgId=1&var-PROMETHEUS_DS=Global&var-environment=gstg
  • What changes to this metric should prompt a rollback: Sustained increase above baseline.
• Metric: Operation Rate - Replicas
  • Location: https://dashboards.gitlab.net/d/redis-cache-main/redis-cache-overview?orgId=1&var-PROMETHEUS_DS=Global&var-environment=gstg
  • What changes to this metric should prompt a rollback: Replicas not returning into a stable state.

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.