Fix ArgoCD Cluster Secret Invalid

The Problem

ArgoCD shows Cluster Secret Invalid. This prevents normal GitOps operations.

Diagnosis

# Check application status
argocd app get my-app

# Check ArgoCD controller logs
kubectl logs -n argocd deployment/argocd-application-controller --tail=100

# Check repo-server logs
kubectl logs -n argocd deployment/argocd-repo-server --tail=100

# Check ArgoCD server logs
kubectl logs -n argocd deployment/argocd-server --tail=100

Common Causes and Fixes

1. Check ArgoCD Version

argocd version
# Ensure client and server versions match

2. Restart ArgoCD Components

kubectl rollout restart deployment/argocd-application-controller -n argocd
kubectl rollout restart deployment/argocd-repo-server -n argocd
kubectl rollout restart deployment/argocd-server -n argocd

3. Clear Application Cache

# Hard refresh clears the manifest cache
argocd app get my-app --hard-refresh

4. Check RBAC Permissions

# Verify ArgoCD has permissions in target namespace
kubectl auth can-i create deployments --as=system:serviceaccount:argocd:argocd-application-controller -n target-namespace

5. Validate Manifests

# Test manifests locally
kubectl apply --dry-run=client -f manifests/

# Check for Kustomize/Helm errors
argocd app manifests my-app

Prevention

• Pin ArgoCD version and test upgrades in staging first
• Use health checks and sync windows for production applications
• Monitor ArgoCD metrics with Prometheus
• Set resource limits on ArgoCD components to prevent OOM

Related Resources

• ArgoCD Cheat Sheet
• Install ArgoCD on Kubernetes
• ArgoCD vs Flux