Argo CD is a declarative GitOps continuous delivery tool for Kubernetes that syncs application state from Git repositories.
Installation
bash
# Install Argo CD on Kubernetes
kubectl create namespace argocd
kubectl apply -n argocd -f https://raw.githubusercontent.com/argoproj/argo-cd/stable/manifests/install.yaml
# Install CLI
curl -sSL -o argocd https://github.com/argoproj/argo-cd/releases/latest/download/argocd-linux-amd64
chmod +x argocd && sudo mv argocd /usr/local/bin/
# Get initial admin password
argocd admin initial-password -n argocd
# Login
argocd login argocd.example.com --grpc-web
Application Definitions
yaml
# apps/web-app.yaml — Basic ArgoCD Application manifest
apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
name: web-app
namespace: argocd
finalizers:
- resources-finalizer.argocd.argoproj.io
spec:
project: default
source:
repoURL: https://github.com/myorg/web-app.git
targetRevision: main
path: k8s/overlays/production
destination:
server: https://kubernetes.default.svc
namespace: web-app
syncPolicy:
automated:
prune: true
selfHeal: true
allowEmpty: false
syncOptions:
- CreateNamespace=true
- PrunePropagationPolicy=foreground
- PruneLast=true
retry:
limit: 5
backoff:
duration: 5s
factor: 2
maxDuration: 3m
yaml
# apps/helm-app.yaml — Application using Helm chart source
apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
name: monitoring
namespace: argocd
spec:
project: default
source:
repoURL: https://prometheus-community.github.io/helm-charts
chart: kube-prometheus-stack
targetRevision: 55.0.0
helm:
releaseName: monitoring
valuesObject:
grafana:
enabled: true
ingress:
enabled: true
hosts:
- grafana.example.com
prometheus:
prometheusSpec:
retention: 30d
storageSpec:
volumeClaimTemplate:
spec:
accessModes: ["ReadWriteOnce"]
resources:
requests:
storage: 50Gi
destination:
server: https://kubernetes.default.svc
namespace: monitoring
syncPolicy:
automated:
prune: true
selfHeal: true
syncOptions:
- CreateNamespace=true
- ServerSideApply=true
App of Apps Pattern
yaml
# apps/root-app.yaml — Root application that manages other apps
apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
name: root-app
namespace: argocd
spec:
project: default
source:
repoURL: https://github.com/myorg/gitops-config.git
targetRevision: main
path: apps
destination:
server: https://kubernetes.default.svc
namespace: argocd
syncPolicy:
automated:
prune: true
selfHeal: true
ApplicationSet
yaml
# appsets/multi-cluster.yaml — Deploy to multiple clusters automatically
apiVersion: argoproj.io/v1alpha1
kind: ApplicationSet
metadata:
name: web-app-set
namespace: argocd
spec:
generators:
- clusters:
selector:
matchLabels:
environment: production
template:
metadata:
name: "web-app-{{name}}"
spec:
project: default
source:
repoURL: https://github.com/myorg/web-app.git
targetRevision: main
path: k8s/overlays/production
destination:
server: "{{server}}"
namespace: web-app
syncPolicy:
automated:
prune: true
selfHeal: true
Projects
yaml
# projects/team-a.yaml — ArgoCD project with RBAC restrictions
apiVersion: argoproj.io/v1alpha1
kind: AppProject
metadata:
name: team-a
namespace: argocd
spec:
description: "Team A applications"
sourceRepos:
- "https://github.com/myorg/team-a-*"
destinations:
- namespace: "team-a-*"
server: https://kubernetes.default.svc
clusterResourceWhitelist:
- group: ""
kind: Namespace
namespaceResourceBlacklist:
- group: ""
kind: ResourceQuota
- group: ""
kind: LimitRange
roles:
- name: developer
policies:
- p, proj:team-a:developer, applications, get, team-a/*, allow
- p, proj:team-a:developer, applications, sync, team-a/*, allow
groups:
- team-a-devs
Sync Waves and Hooks
yaml
# k8s/namespace.yaml — Resource with sync wave annotation
apiVersion: v1
kind: Namespace
metadata:
name: web-app
annotations:
argocd.argoproj.io/sync-wave: "-1"
---
# k8s/migration-job.yaml — Pre-sync hook for database migration
apiVersion: batch/v1
kind: Job
metadata:
name: db-migrate
annotations:
argocd.argoproj.io/hook: PreSync
argocd.argoproj.io/hook-delete-policy: HookSucceeded
spec:
template:
spec:
containers:
- name: migrate
image: myregistry.com/web-app:latest
command: ["python", "manage.py", "migrate"]
restartPolicy: Never
Common Commands
bash
# Application management
argocd app create web-app -f apps/web-app.yaml
argocd app list
argocd app get web-app
argocd app sync web-app
argocd app sync web-app --force --prune
argocd app delete web-app --cascade
# Diff and history
argocd app diff web-app
argocd app history web-app
argocd app rollback web-app <history-id>
# Repository management
argocd repo add https://github.com/myorg/config.git --username git --password $TOKEN
argocd repo list
# Cluster management
argocd cluster add my-cluster-context
argocd cluster list
# Account management
argocd account update-password
argocd account list