[CR][GSTG] Migrate cache workload to redis-cluster-cache
Production Change
Change Summary
This closes the provisioning issue and migrates cache workload on gstg.
The secondary objectives of this migration on gstg
are:
- Rehearsing the cache-warmup with dual-write and validator script's extra migration
- Practice a rollback (diverting read traffic back to
redis-cache
)
Feature flag rollout issue: gitlab-org/gitlab#415029 (closed)
Change Details
- Services Impacted - ServiceRedisCache ServiceRedisClusterCache
- Change Technician - @schin1
- Change Reviewer - @stejacks-gitlab
- Time tracking - ~72 hours (3 days)
- Downtime Component - NA
Detailed steps for the change
Change Steps - steps to take to execute the change
Estimated Time to Complete (48hr)
Complete provisioning step
-
Set label changein-progress /label ~change::in-progress
-
Merge gitlab-com/gl-infra/k8s-workloads/gitlab-com!2810 (merged) -
Update console VM's detail using https://gitlab.com/gitlab-com/gl-infra/chef-repo/-/merge_requests/3655 -
Check the dashboard for application connection to the Redis server
Cache warming
-
To start dual-write: Enable the use_primary_and_secondary_stores_for_cache
feature flag forgstg
-
/chatops run feature set use_primary_and_secondary_stores_for_cache true --staging
-
-
Wait for 24 hours -
Run validator script https://gitlab.com/gitlab-com/runbooks/-/blob/master/scripts/redis_diff.rb from a console VM with redis-cache
as the source whileredis-cluster-cache
as the destination
Cutover reads
-
To cutover: Enable use_primary_store_as_default_for_cache
to cut over read traffic./chatops run feature set use_primary_store_as_default_for_cache true --staging
Click to show removed component
Rollback reads
-
Run validator script https://gitlab.com/gitlab-com/runbooks/-/blob/master/scripts/redis_diff.rb from a console VM ( redis-cache
as the destination whileredis-cluster-cache
as the source) -
To cutover: Disable use_primary_store_as_default_for_cache
to cut over read traffic. -
observe for a period of time -
Run validator script https://gitlab.com/gitlab-com/runbooks/-/blob/master/scripts/redis_diff.rb from a console VM with redis-cache
as the source whileredis-cluster-cache
as the destination
Cutover read and write
-
Disable use_primary_and_secondary_stores_for_cache
to halt double-write. -
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) - Estimated Time to Complete in Minutes
-
Disable use_primary_store_as_default_for_cache
anduse_primary_and_secondary_stores_for_cache
feature flags -
Revert https://gitlab.com/gitlab-com/gl-infra/chef-repo/-/merge_requests/3655 -
Revert console VM MR https://gitlab.com/gitlab-com/gl-infra/chef-repo/-/merge_requests/3656 and remove secret from omnibus vault -
Set label changeaborted /label ~change::aborted
Monitoring
Key metrics to observe
-
Metric: service apdex and error ratio
- Location: https://dashboards.gitlab.net/d/redis-cluster-cache-main/redis-cluster-cache-overview?orgId=1&var-PROMETHEUS_DS=Global&var-environment=gstg&var-shard=All
- What changes to this metric should prompt a rollback: apdex abnormally and/or high error ratio
-
Metric: primary_redis_cpu saturation ratio
- Location: https://dashboards.gitlab.net/d/redis-cluster-cache-main/redis-cluster-cache-overview?orgId=1&var-PROMETHEUS_DS=Global&var-environment=gstg&var-shard=All
- What changes to this metric should prompt a rollback: NA
Change Reviewer checklist
-
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.
-
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 Sylvester Chin