Switch 'shared' runners shard to use ci-gateway ILB

Production Change

Change Summary

Follow-up for #6375 (closed).

As part of https://gitlab.com/groups/gitlab-org/-/epics/7212 we're introducing a new networking setup for ServiceCI Runners and executed jobs. This configuration will move the Runner API communication and Git operations done for the purpose of executed jobs off the public Internet to a private networking within GCP.

The detailed description of the plan was discussed at https://gitlab.com/gitlab-com/gl-infra/infrastructure/-/issues/14874. The issue contains also results of our tests on staging.gitlab.com.

This change will guide us through steps needed to move the GitLab.com workloads executed on ServiceCI Runners to a similar setup.

Change Details

1. Services Impacted - ServiceCI Runners
2. Change Technician - @tmaczukin
3. Change Reviewer - @ahmadsherif
4. Time tracking - 30 min
5. Downtime Component - No downtime is expected

Detailed steps for the change

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

Estimated Time to Complete (mins) - 1 min

• Set label changein-progress on this issue

Change Steps - steps to take to execute the change

Estimated Time to Complete (mins) - 10 min

• Merge https://gitlab.com/gitlab-com/gl-infra/chef-repo/-/merge_requests/1523 https://gitlab.com/gitlab-com/gl-infra/chef-repo/-/merge_requests/1531+
• Wait for changes to be applied through CI

Post-Change Steps - steps to take to verify the change

Estimated Time to Complete (mins) - 5 min

• Run test pipeline https://gitlab.com/tmaczukin-test-projects/test-git.ci-gateway-usage/-/pipelines/new?ref=test-with-submodules to verify that jobs are still working properly - check the jobs with shared in the name

Rollback

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

Estimated Time to Complete (mins) - 10 min

• Re-open and merge https://gitlab.com/gitlab-com/gl-infra/chef-repo/-/merge_requests/1532+

• Wait for changes to be applied through CI

• Force chef-client run on the active deployments of shared runners shard.

  Active deployment can be found at: https://dashboards.gitlab.net/d/ci-runners-deployment/ci-runners-deployment-overview?orgId=1&var-PROMETHEUS_DS=Global&var-environment=gprd&var-stage=main&var-shard=shared&var-runner_manager=All&var-runner_job_failure_reason=All&viewPanel=13.

There is no need to handle blue/green switch here and wait for draining. This change requires just configuration file update via chef-client run on an active deployment. Please do not use blue/green switch procedure and instead simply merge the chef-repo MR and wait for chef-client to apply them (or manually force chef-client to do so on the active shared nodes).

Monitoring

Key metrics to observe

• Metric: Failures on GitLab Inc. runners (by instance,failure_reason)

  • Location: https://dashboards.gitlab.net/d/ci-runners-incident-runner-manager/ci-runners-incident-support-runner-manager?orgId=1&var-PROMETHEUS_DS=Global&var-environment=gprd&var-stage=main&var-shard=shared&var-runner_manager=All&var-jobs_running_for_project=0&var-runner_job_failure_reason=All&from=now-1h&to=now&viewPanel=23 Hide charts

  • What changes to this metric should prompt a rollback:

    A peak in job failures at the on the related shard and at the moment of applying the change. If it will rise significantly and stay like that, it may mean something is wrong. Looking into logs and checking random jobs will be needed to confirm if there is a problem caused to our change or no.

• Metric: all

  • Location: https://dashboards.gitlab.net/d/frontend-git-haproxy/frontend-ci-gateway-git-utilisation-based-on-haproxy

  • What changes to this metric should prompt a rollback:

    Hard to say. It's a new dashboard that we've created to analyze the new internal traffic. So probably no change visible on the dashboard after applying configuration changes would be a signal that something is not right.

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?

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.