Runbook: ArgoCD App Out of Sync

Alert name: ArgoCDAppOutOfSync

An ArgoCD application has been out of sync for 30+ minutes. This means the live state in Kubernetes differs from what’s declared in Git.

Diagnostic Steps

1. Check which app is out of sync — the name label in the alert tells you:

   argocd app get <app-name>

2. View the diff:

   argocd app diff <app-name>

3. Check if it’s a branch revision issue — during C1/C2 work, apps may be pointed at a feature branch. After merge, they need to be reset to main:

   argocd app get <app-name> -o json | python3 -c "import json,sys; print(json.load(sys.stdin)['spec']['source']['targetRevision'])"

4. Check ArgoCD UI — https://argocd.ops.eblu.me — look for sync errors or degraded status.

Common Causes

• Forgot to sync after push — ArgoCD uses manual sync; changes require explicit argocd app sync
• Branch revision not reset after PR merge — app still points at a deleted branch
• Kustomize/manifest error — invalid YAML or unsatisfiable resource requirements
• Pruning needed — old ConfigMaps from configMapGenerator need pruning

Resolution

# Simple sync
argocd app sync <app-name>
 
# If pruning is needed
argocd app sync <app-name> --prune
 
# If stuck on a deleted branch
argocd app set <app-name> --revision main
argocd app sync <app-name>

Silencing

During active C1/C2 development, apps may intentionally be out of sync:

1. Grafana → Alerting → Silences → Create Silence
2. Match alertname = ArgoCDAppOutOfSync and name = <app-name>

Related

• argocd — ArgoCD reference
• deploy-infra-alerting — Alerting pipeline overview