ArgoCD GitOps

Implement declarative continuous delivery for Kubernetes with ArgoCD.

When to Use This Skill

Use this skill when:

• Implementing GitOps workflows for Kubernetes

• Automating deployments from Git repositories

• Managing multiple environments declaratively

• Implementing progressive delivery strategies

• Synchronizing cluster state with Git

Prerequisites

• Kubernetes cluster with ArgoCD installed

• kubectl configured

• Git repository for manifests

• ArgoCD CLI (optional)

Installation

Create namespace

kubectl create namespace argocd

Install ArgoCD

kubectl apply -n argocd -f https://raw.githubusercontent.com/argoproj/argo-cd/stable/manifests/install.yaml

Get admin password

kubectl -n argocd get secret argocd-initial-admin-secret
-o jsonpath="{.data.password}" | base64 -d

Port forward to access UI

kubectl port-forward svc/argocd-server -n argocd 8080:443

Login with CLI

argocd login localhost:8080

Application Definition

Basic Application

apiVersion: argoproj.io/v1alpha1 kind: Application metadata: name: myapp namespace: argocd spec: project: default source: repoURL: https://github.com/org/myapp-manifests.git targetRevision: main path: environments/production destination: server: https://kubernetes.default.svc namespace: myapp syncPolicy: automated: prune: true selfHeal: true syncOptions: - CreateNamespace=true

Helm Application

apiVersion: argoproj.io/v1alpha1 kind: Application metadata: name: myapp-helm namespace: argocd spec: project: default source: repoURL: https://github.com/org/myapp-chart.git targetRevision: main path: charts/myapp helm: valueFiles: - values.yaml - values-production.yaml parameters: - name: replicaCount value: "3" - name: image.tag value: "2.0.0" destination: server: https://kubernetes.default.svc namespace: myapp syncPolicy: automated: prune: true selfHeal: true

Kustomize Application

apiVersion: argoproj.io/v1alpha1 kind: Application metadata: name: myapp-kustomize namespace: argocd spec: project: default source: repoURL: https://github.com/org/myapp-manifests.git targetRevision: main path: overlays/production kustomize: images: - myapp=myregistry/myapp:2.0.0 destination: server: https://kubernetes.default.svc namespace: myapp

Projects

apiVersion: argoproj.io/v1alpha1 kind: AppProject metadata: name: myproject namespace: argocd spec: description: My Project sourceRepos: - https://github.com/org/* destinations: - namespace: myapp-* server: https://kubernetes.default.svc clusterResourceWhitelist: - group: '' kind: Namespace namespaceResourceWhitelist: - group: '' kind: '' roles: - name: developer description: Developer role policies: - p, proj:myproject:developer, applications, get, myproject/, allow - p, proj:myproject:developer, applications, sync, myproject/, allow groups: - developers

Application Sets

Git Generator

apiVersion: argoproj.io/v1alpha1 kind: ApplicationSet metadata: name: myapp-environments namespace: argocd spec: generators: - git: repoURL: https://github.com/org/myapp-manifests.git revision: main directories: - path: environments/* template: metadata: name: 'myapp-{{path.basename}}' spec: project: default source: repoURL: https://github.com/org/myapp-manifests.git targetRevision: main path: '{{path}}' destination: server: https://kubernetes.default.svc namespace: 'myapp-{{path.basename}}' syncPolicy: automated: prune: true selfHeal: true

List Generator

apiVersion: argoproj.io/v1alpha1 kind: ApplicationSet metadata: name: myapp-clusters namespace: argocd spec: generators: - list: elements: - cluster: production url: https://prod-cluster.example.com - cluster: staging url: https://staging-cluster.example.com template: metadata: name: 'myapp-{{cluster}}' spec: project: default source: repoURL: https://github.com/org/myapp-manifests.git targetRevision: main path: 'environments/{{cluster}}' destination: server: '{{url}}' namespace: myapp

Matrix Generator

apiVersion: argoproj.io/v1alpha1 kind: ApplicationSet metadata: name: myapp-matrix namespace: argocd spec: generators: - matrix: generators: - git: repoURL: https://github.com/org/myapp-manifests.git revision: main directories: - path: apps/* - list: elements: - env: staging - env: production template: metadata: name: '{{path.basename}}-{{env}}' spec: project: default source: repoURL: https://github.com/org/myapp-manifests.git targetRevision: main path: '{{path}}/overlays/{{env}}' destination: server: https://kubernetes.default.svc namespace: '{{path.basename}}-{{env}}'

Sync Policies

Automated Sync

syncPolicy: automated: prune: true # Delete resources not in Git selfHeal: true # Revert manual changes allowEmpty: false # Don't sync empty directories syncOptions: - CreateNamespace=true - PrunePropagationPolicy=foreground - PruneLast=true retry: limit: 5 backoff: duration: 5s factor: 2 maxDuration: 3m

Sync Waves

In Kubernetes manifests

apiVersion: v1 kind: ConfigMap metadata: name: myconfig annotations: argocd.argoproj.io/sync-wave: "-1" # Sync first

apiVersion: apps/v1 kind: Deployment metadata: name: myapp annotations: argocd.argoproj.io/sync-wave: "0" # Sync second

Sync Hooks

apiVersion: batch/v1 kind: Job metadata: name: migration annotations: argocd.argoproj.io/hook: PreSync argocd.argoproj.io/hook-delete-policy: HookSucceeded spec: template: spec: containers: - name: migrate image: myapp:latest command: ["./migrate.sh"] restartPolicy: Never

CLI Commands

List applications

argocd app list

Get application details

argocd app get myapp

Sync application

argocd app sync myapp

Force sync (ignore differences)

argocd app sync myapp --force

View diff

argocd app diff myapp

Rollback

argocd app rollback myapp

Delete application

argocd app delete myapp

View logs

argocd app logs myapp

Hard refresh (clear cache)

argocd app get myapp --hard-refresh

Repository Configuration

apiVersion: v1 kind: Secret metadata: name: private-repo namespace: argocd labels: argocd.argoproj.io/secret-type: repository stringData: url: https://github.com/org/private-repo.git username: git password: ghp_xxxx

SSH key

apiVersion: v1 kind: Secret metadata: name: private-repo-ssh namespace: argocd labels: argocd.argoproj.io/secret-type: repository stringData: url: git@github.com:org/private-repo.git sshPrivateKey: | -----BEGIN OPENSSH PRIVATE KEY----- ... -----END OPENSSH PRIVATE KEY-----

Notifications

apiVersion: v1 kind: ConfigMap metadata: name: argocd-notifications-cm namespace: argocd data: service.slack: | token: $slack-token template.app-deployed: | message: Application {{.app.metadata.name}} is now {{.app.status.sync.status}}. trigger.on-deployed: | - when: app.status.operationState.phase in ['Succeeded'] send: [app-deployed]

Common Issues

Issue: Sync Fails with Diff

Problem: Resources show differences but are correct Solution: Configure ignore differences

spec: ignoreDifferences: - group: apps kind: Deployment jsonPointers: - /spec/replicas

Issue: Repository Not Accessible

Problem: ArgoCD cannot clone repository Solution: Check repository secret, verify URL and credentials

Issue: Application Stuck OutOfSync

Problem: Application never becomes synced Solution: Check resource status, review events, verify manifests

Issue: Health Check Failing

Problem: Application shows degraded health Solution: Check custom health checks, verify probe configurations

Best Practices

• Use ApplicationSets for multi-environment deployments

• Implement sync waves for ordered deployments

• Use projects to isolate applications

• Configure notifications for deployment events

• Implement proper RBAC with projects

• Use health checks for deployment verification

• Enable auto-pruning to remove deleted resources

• Keep manifests in dedicated repositories

Related Skills

• kubernetes-ops - K8s fundamentals

• helm-charts - Helm deployments

• kustomize - Kustomize overlays