In this article, we will analyze why Argo CD deployments may become stuck, explore debugging techniques, and provide best practices for ensuring reliable GitOps-based deployments.

Understanding Stuck or Failing Argo CD Syncs

Argo CD sync failures occur when the desired state in Git does not match the actual Kubernetes state, often due to:

  • Orphaned resources remaining after failed syncs.
  • Conflicting or manually modified Kubernetes objects.
  • Resource hooks blocking or delaying deployment.
  • Permissions issues preventing Argo CD from applying updates.

Common Symptoms

  • Argo CD showing Progressing or OutOfSync indefinitely.
  • Sync failing with Unable to apply resource errors.
  • Unexpected rollbacks due to conflicting resources.
  • Pods stuck in ImagePullBackOff or CrashLoopBackOff.

Diagnosing Argo CD Sync Issues

1. Checking Application Status

Use the Argo CD CLI to inspect application sync state:

argocd app get my-app

Look for stuck resources under OutOfSync status.

2. Viewing Detailed Sync Logs

Fetch detailed logs to identify deployment errors:

argocd app history my-app

3. Debugging Resource Reconciliation

Check resource status and last applied manifests:

kubectl get events --namespace=my-namespace
kubectl describe pod my-pod

4. Identifying Manual Changes

Check for manual updates that may conflict with Git:

argocd app diff my-app

Fixing Stuck or Failing Argo CD Syncs

Solution 1: Forcing a Manual Sync

Reset application state by forcing a sync:

argocd app sync my-app --force

Solution 2: Pruning Orphaned Resources

Enable automatic resource pruning to remove orphaned objects:

argocd app set my-app --auto-prune

Solution 3: Enabling Self-Healing Mode

Configure Argo CD to automatically detect and fix drift:

argocd app set my-app --self-heal

Solution 4: Fixing Hook Execution Order

If sync hooks are delaying deployment, inspect and adjust them:

kubectl get events --namespace=my-namespace

Modify hooks in argocd-cm ConfigMap if necessary.

Solution 5: Resolving Kubernetes API Permission Issues

Check Argo CD permissions and service account bindings:

kubectl auth can-i list pods --as=system:serviceaccount:argocd:argocd-server

If necessary, grant missing permissions:

kubectl create clusterrolebinding argocd-admin --clusterrole=cluster-admin --serviceaccount=argocd:argocd-server

Best Practices for Reliable Argo CD Deployments

  • Use auto-prune and self-heal to prevent orphaned resources.
  • Regularly check argocd app diff for unintended manual changes.
  • Define clear sync hooks to prevent deployment delays.
  • Ensure Argo CD has correct Kubernetes API permissions.
  • Use progressive rollouts (e.g., Blue-Green, Canary) to minimize risk.

Conclusion

Stuck or failing syncs in Argo CD can disrupt Kubernetes deployments, but by diagnosing issues with the CLI, enforcing self-healing, and managing resource drift effectively, teams can maintain stable and automated GitOps workflows.

FAQ

1. Why is my Argo CD application stuck in Progressing?

It may be due to pending resource hooks, manual changes, or failed sync operations.

2. How do I fix an Argo CD sync that is stuck?

Use argocd app sync my-app --force to manually resolve stuck syncs.

3. What does OutOfSync mean in Argo CD?

It indicates that the Kubernetes cluster state differs from the desired Git state.

4. How do I prevent manual changes from affecting Argo CD syncs?

Enable auto-prune and self-heal to automatically fix drift.

5. What permissions does Argo CD need to deploy applications?

Argo CD requires sufficient RBAC permissions to manage resources in the target namespaces.