docusaurus/docusaurus/docs/services/argocd.md

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ArgoCD

Overview

ArgoCD is our GitOps continuous delivery tool. It automatically synchronizes applications from our Git repository to Kubernetes.

How It Works

graph LR
    A[Git Repository] -->|Watch| B[ArgoCD]
    B -->|Compare| C[Desired State]
    B -->|Compare| D[Actual State in K8s]
    B -->|Sync| E[Deploy Changes]

Application Structure

Each service has an ArgoCD Application definition:

apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: example-service
  namespace: argocd
spec:
  project: default
  source:
    repoURL: https://github.com/K3S-HOME/infrastructure.git
    targetRevision: main
    path: example-service
  destination:
    server: https://kubernetes.default.svc
    namespace: example-service
  syncPolicy:
    automated:
      prune: true
      selfHeal: true

Key Features

Automated Sync

• prune: true: Removes resources deleted from Git
• selfHeal: true: Reverts manual changes to match Git
• allowEmpty: false: Prevents accidental empty deployments

Manual Operations

# List applications
sudo kubectl get applications -n argocd

# View application status
sudo kubectl get application -n argocd <app-name> -o yaml

# Force refresh
argocd app get <app-name> --refresh

Deployment Workflow

1. Make Changes

Edit files in the infrastructure repository:

cd /path/to/infrastructure
vim example-service/deployment.yaml
git add .
git commit -m "update deployment"
git push

2. ArgoCD Detects Changes

• Polls Git repository every 3 minutes
• Or immediately via webhook (if configured)

3. Automatic Sync

• Compares desired state (Git) vs actual state (K8s)
• Applies changes automatically
• Reports status

4. Monitor Deployment

# Check application sync status
sudo kubectl get applications -n argocd

# Watch pod rollout
sudo kubectl rollout status deployment/<name> -n <namespace>

Common Patterns

Adding a New Service

1. Create service directory: infrastructure/my-service/
2. Add Kubernetes manifests
3. Create kustomization.yaml
4. Add ArgoCD Application: infrastructure/my-service/argocd/my-service.yaml
5. Reference in main kustomization.yaml
6. Git push → ArgoCD deploys automatically

Updating a Service

1. Edit deployment.yaml or other files
2. Git commit & push
3. Wait for ArgoCD sync (or force refresh)
4. Verify deployment

Rolling Back

# Method 1: Git revert
git revert <commit-hash>
git push

# Method 2: Sync to specific commit
argocd app sync <app-name> --revision <commit-hash>

Troubleshooting

Sync Stuck

# Force hard refresh
sudo kubectl patch application -n argocd <app-name> \
  -p '{"metadata": {"annotations": {"argocd.argoproj.io/refresh": "hard"}}}' \
  --type merge

Out of Sync

Check what's different:

argocd app diff <app-name>

Sync Failed

View detailed error:

sudo kubectl describe application -n argocd <app-name>

Best Practices

1. Always use Git: Don't make manual kubectl changes
2. Small commits: Easier to review and rollback
3. Test locally: Use kubectl apply --dry-run=client
4. Use pruning: Keep cluster clean with prune: true
5. Enable selfHeal: Prevent configuration drift

Next Steps

• Monitoring with Prometheus
• Kubernetes Operations