2023-03-27: Route imports to memory-bound

Production Change

Change Summary

We currently have a dedicated low-traffic shard called imports. The memory-bound shard has similar characteristics and also very low traffic. This change makes the memory-bound shard support long running jobs by applying similar settings as the imports shard, bumps up the max number of replicas, and moves the imports workload there to run more efficiently and hopefully have less noisy alerts. This adjustment will also support long running export jobs on this shard better.

Once confirmed that the imports shard is completely idle, we'll remove the shard entirely.

Change Details

1. Services Impacted - ServiceSidekiq
2. Change Technician - @gsgl
3. Change Reviewer - @ggillies
4. Time tracking - 30min
5. Downtime Component - none

Detailed steps for the change

Change Steps - steps to take to execute the change

Estimated Time to Complete (mins) - 30m

• Set label changein-progress /label ~change::in-progress
• Merge gitlab-com/gl-infra/k8s-workloads/gitlab-com!2626 (merged)
• Merge https://gitlab.com/gitlab-com/gl-infra/chef-repo/-/merge_requests/3104
• Check metrics/logs to ensure things are working as expected (see Monitoring section)
• Attempt a project import
• Set label changecomplete /label ~change::complete

By this stage, import jobs have been verified to be working as expected and the imports shard is completely idle:

• Remove configuration for the imports shard:
  • runbooks: gitlab-com/runbooks!5615 (merged)
  • tanka: gitlab-com/gl-infra/k8s-workloads/tanka-deployments!710 (merged)
  • gitlab-com: gitlab-com/gl-infra/k8s-workloads/gitlab-com!2630 (merged)

Rollback

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

Estimated Time to Complete (mins) - 15m

• Revert gitlab-com/gl-infra/k8s-workloads/gitlab-com!2626 (merged)
• Revert https://gitlab.com/gitlab-com/gl-infra/chef-repo/-/merge_requests/3104
• Set label changeaborted /label ~change::aborted

Monitoring

Key metrics to observe

• Metric: Sidekiq imports Detail Dashboard

  • Location: https://dashboards.gitlab.net/goto/_NaF1aB4k?orgId=1
  • What changes to this metric should prompt a rollback: Import jobs should drop to 0.

• Metric: Sidekiq memory-bound Detail Dashboard

  • Location: https://dashboards.gitlab.net/goto/5ocvG-B4k?orgId=1
  • What changes to this metric should prompt a rollback: Workers previously going to the imports shard (BulkImports::PipelineWorker, BulkImports::RelationExportWorker, RepositoryImportWorker) should appear in this dashboard.

• Logs:

  • Location: https://log.gprd.gitlab.net/goto/2fa9af20-cc46-11ed-8afc-c9851e4645c0
  • What changes to this metric should prompt a rollback: unexpected spike of errors.

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.