Skip to content

2025-08-27: macos runners update to 18.3.0~pre.128.g86b6c639-1 and host images upgrade

Production Change

Change Summary

This upgrades the runner version for inactive macOS runners to 18.3.0~pre.128.g86b6c639-1. The macOS host image is also upgraded here, which has already been merged via https://ops.gitlab.net/gitlab-com/gl-infra/config-mgmt/-/merge_requests/11856.

MR to be reviewed: https://gitlab.com/gitlab-com/gl-infra/chef-repo/-/merge_requests/6353+

We tried 18.4 previously but this was aborted due to incompatibilities of the caching command. See also #20430 (comment 2712197274)

See also https://gitlab.com/gitlab-com/gl-infra/production-engineering/-/issues/27408+

Upgrades these inactive shards for macos runners:

Shard Name Inactive deployment color
saas-macos-staging 🟢 green
saas-macos-medium-m1 🔵 blue
saas-macos-large-m2pro 🟢 green

Change Details

  1. Services Impacted - ServiceCI Runners
  2. Change Technician - @joe-shaw
  3. Change Reviewer - @rehab
  4. Scheduled Date and Time (UTC in format YYYY-MM-DD HH:MM) - 2025-08-27 19:00
  5. Time tracking - 90 minutes
  6. Downtime Component - none

Set Maintenance Mode in GitLab

If your change involves scheduled maintenance, add a step to set and unset maintenance mode per our runbooks. This will make sure SLA calculations adjust for the maintenance period.

Detailed steps for the change

Pre-execution steps

  • Make sure all tasks in Change Technician checklist are done
  • 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.)
    • The SRE on-call provided approval with the eoc_approved label on the issue.
  • For C1, C2, or blocks deployments change issues, Release managers have been informed 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.

Change steps - steps to take to execute the change

  • Set label changein-progress /label ~change::in-progress

  • Check that the m2pro AWS environment (acc 730335264460) has enough dedicated hosts to scale into. Ideally there are enough spare hosts to handle the current job load.

    • You should already have access to the AWS account for macOS runners: navigate to us-east-1 -> EC2 -> Dedicated Hosts. There should be at least 4 "empty" hosts there ready to be used.

  • Merge MR to upgrade the gitlab-runner version on the inactive shards: https://gitlab.com/gitlab-com/gl-infra/chef-repo/-/merge_requests/6353

  • Shift the traffic to the inactive fleet.

    • Inform the EOC via #production 
      @sre-oncall I'm going to shift traffic to the upgraded deployments for the Macos Runners shards `saas-macos-large-m2pro`, `saas-macos-medium-m1` and `saas-macos-staging`. Details in https://gitlab.com/gitlab-com/gl-infra/production/-/issues/20430.
    saas-macos-staging/green
    saas-macos-medium-m1/blue
    • Start saas-macos-medium-m1/blue via #production 
      /runner run start saas-macos-medium-m1 blue
      • Wait for new deployments to start executing jobs (check the dashboard).
      • Confirm saas-macos-medium-m1/blue started accepting new jobs
      • Stop saas-macos-medium-m1/green (double check the previously active color) via #production 
        /runner run stop saas-macos-medium-m1 green
    saas-macos-large-m2pro/green
    • Start saas-macos-large-m2pro/green via #production 
      /runner run start saas-macos-large-m2pro green
      • Wait for new deployment to start executing jobs (check the dashboard).
      • Confirm saas-macos-large-m2pro/green started accepting new jobs
      • Stop saas-macos-large-m2pro/blue (double check the previously active color) via #production 
        /runner run stop saas-macos-large-m2pro blue

  • Inform EOC that the procedure is finished. In the thread started at #production with the first message post:

    @sre-oncall This has been completed. New colors are taking the jobs.
Previous colors are in the draining state and will be completely drained within the next 2-3 hours.

  • 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 (60 mins)

  • Revert linked MRs
  • Reverse the rollout steps above. If necessary, start any stopped deployments and stop newly started deployments.
  • Set label changeaborted /label ~change::aborted

Monitoring

Key metrics to observe

Metric: CI Runners Overview

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 change window has been agreed with Release Managers in advance of the change. If the change is planned for APAC hours, this issue has an agreed pre-change approval.
    • The labels blocks deployments and/or blocks feature-flags are applied as necessary.

Change Technician checklist

  • 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 Infrastructure Manager provided approval with the manager_approved label on the issue. Mention @gitlab-org/saas-platforms/inframanagers in this issue to request approval and provide visibility to all infrastructure managers.
  • For C1, C2, or blocks deployments change issues, confirm with Release managers that the change does not overlap or hinder any release process (In #production channel, mention @release-managers and this issue and await their acknowledgment.)
Edited by Joe Shaw