How to fix Flux Reconciliation Failed in Kubernetes

kubectl get kustomization -A
kubectl get helmrelease -A

# Get detailed status:
kubectl describe kustomization <name> -n <namespace>
kubectl describe helmrelease <name> -n <namespace>

# Check events:
kubectl get events -n flux-system --sort-by=.metadata.creationTimestamp

kubectl logs -n flux-system deployment/kustomize-controller -f
kubectl logs -n flux-system deployment/helm-controller -f
kubectl logs -n flux-system deployment/source-controller -f

# Search for specific error:
kubectl logs -n flux-system -l app=kustomize-controller | grep -i error
kubectl logs -n flux-system -l app=helm-controller | grep -i error

# Previous logs if pod restarted:
kubectl logs -n flux-system deployment/kustomize-controller --previous

# Clone repository:
git clone <git-repo-url>
cd <repo-path>

# Validate YAML:
kubectl apply -f . --dry-run=client
kubectl apply -f kustomization.yaml --dry-run=client

# Or use kubeval:
kubectl apply -f . --dry-run=client 2>&1 | grep -i error

# For Kustomize:
kustomize build . | kubectl apply --dry-run=client -f -

# For Helm:
helm template <release> <chart> | kubectl apply --dry-run=client -f -

kubectl get gitrepository -A
kubectl describe gitrepository <name> -n <namespace>

# Check for authentication errors:
kubectl logs -n flux-system deployment/source-controller | grep -i auth

# Verify SSH key or token:
kubectl get secret <git-secret> -n flux-system -o yaml | grep ssh-privatekey

# Test SSH connectivity (if using SSH):
kubectl run -it --rm ssh-test --image=alpine/git -- sh
# Inside pod:
git clone <git-repo-url>

# Check which CRDs are installed:
kubectl get crd

# If CRD is missing, install first:
kubectl apply -f crds/  # Apply CRD manifests first

# In Flux manifests, use kustomization ordering:
# 1. First Kustomization: install CRDs
kustomization-crds.yaml:
  - source: Git repo
    path: ./crds
    prune: true

# 2. Second Kustomization: install resources
kustomization-apps.yaml:
  - source: Git repo
    path: ./apps
    dependsOn:
      - kustomization-crds  # Wait for CRDs first

# Check Flux service accounts:
kubectl get sa -n flux-system

# View ClusterRoleBinding for Flux:
kubectl get clusterrolebinding | grep flux
kubectl describe clusterrolebinding flux

# Test permissions:
kubectl auth can-i create deployments --as=system:serviceaccount:flux-system:kustomize-controller -n default

# If permissions missing, add ClusterRole:
kubectl create clusterrolebinding flux-admin --clusterrole=cluster-admin --serviceaccount=flux-system:kustomize-controller

# Check which ConfigMaps/Secrets are referenced:
grep -r "configMapRef\|secretRef" .

# Verify they exist:
kubectl get configmap <name> -n <namespace>
kubectl get secret <name> -n <namespace>

# If missing, create them:
kubectl create configmap app-config --from-file=config.yaml -n <namespace>
kubectl create secret generic db-secret --from-literal=password=xxx -n <namespace>

# Or add to Git:
kubectl create configmap app-config --from-file=config.yaml --dry-run=client -o yaml > configmap.yaml
# Commit configmap.yaml to Git

# Trigger reconciliation:
flux reconcile kustomization <name> -n <namespace>
flux reconcile source git <name> -n <namespace>

# Watch status:
flux get kustomization --watch
flux get source git --watch

# Or kubectl:
kubectl patch kustomization <name> -p '{"spec":{"force":true}}' -n <namespace>

# Verify deployment:
kubectl get deployment <name> -n <namespace>
kubectl rollout status deployment <name> -n <namespace>