2022-08-09: Update the node selectors and add node tolerations to workloads in gprd

Production Change

Change Summary

We want to move the GitLab workloads to node pools with taints so that workloads without a node selector configured don't run on the same node pools as the GitLab services.

The new node pools with taints have been created in https://ops.gitlab.net/gitlab-com/gl-infra/config-mgmt/-/merge_requests/4050

C2 because we don't want deployments to happen while applying this change.

The risks of downtime in case of failure (because of wrong node selector or tolerations) are very low, the deployment rollout would just block and old pods would still keep running, however it would prevent scaling up until the change is reverted.

Issue: delivery#1747 (closed)

Change Details

  1. Services Impacted - ServiceKube ServiceAPI ServiceGitLab Rails ServiceGitLab SSHD ServiceGitlab Shell ServiceContainer Registry ServicePages
  2. Change Technician - @pguinoiseau
  3. Change Reviewer - @ggillies
  4. Time tracking - 30 minutes
  5. Downtime Component - none

Detailed steps for the change

Change Steps - steps to take to execute the change

Estimated Time to Complete (mins) - 30 minutes

  • Make sure a deployment is not currently running
  • Set label changein-progress /label ~change::in-progress
  • Merge gitlab-com/gl-infra/k8s-workloads/gitlab-com!2016 (merged) and make sure the Helm deployment is successful
  • Check the deployments' status in each cluster to make sure they are all healthy and up-to-date: 
    kubectl --context gprd-gitlab-gke --namespace gitlab-cny get deployments
kubectl --context gprd-gitlab-gke --namespace gitlab get deployments
kubectl --context gprd-us-east1-b --namespace gitlab get deployments
kubectl --context gprd-us-east1-c --namespace gitlab get deployments
kubectl --context gprd-us-east1-d --namespace gitlab get deployments
  • 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) - 30 minutes

  • Revert gitlab-com/gl-infra/k8s-workloads/gitlab-com!2016 (merged) and merge
  • Check the deployments' status in each cluster to make sure they are all healthy and up-to-date: 
    kubectl --context gprd-gitlab-gke --namespace gitlab-cny get deployments
kubectl --context gprd-gitlab-gke --namespace gitlab get deployments
kubectl --context gprd-us-east1-b --namespace gitlab get deployments
kubectl --context gprd-us-east1-c --namespace gitlab get deployments
kubectl --context gprd-us-east1-d --namespace gitlab get deployments
  • Set label changeaborted /label ~change::aborted

Monitoring

Key metrics to observe

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.
    • 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 Pierre Guinoiseau