Move ArgoCD to the us-central1 region

Overview

We need to improve ArgoCD's resilience by relocating it from the us-east1 region to us-central1. This migration ensures ArgoCD remains available if the us-east1 region (where GitLab.com currently resides) experiences an outage.

Background

Currently, ArgoCD is deployed in the ops-gitlab-gke cluster in us-east1. To reduce regional dependency and improve disaster recovery capabilities, we're moving it to the ops-central cluster in us-central1.

Migration Approach

The migration will follow a controlled process to minimize downtime:

1. Deploy ArgoCD in ops-central with controllers scaled down
2. Prepare the app-of-apps deployment in new ArgoCD instance
3. Scale down the controllers of the old ArgoCD instance
4. Perform DNS cutover to point to the new instance
5. Scale up the controllers of the new instance and verify that the apps are syncing properly
6. Cleanup and decommission the old deployment

Exit criteria

• ArgoCD is successfully deployed and operational in the ops-central cluster (us-central1 region)
• All applications and application sets are syncing correctly in the new instance
• DNS records updated to point to the new ArgoCD instance
• Old ArgoCD deployment in ops-gitlab-gke is decommissioned
• Runbook documentation updated with new cluster location