What is GitOps?

GitOps is a way to run deployments in which a Git repository holds the desired state, for example Kubernetes manifests or Helm values, and a software agent inside the target environment keeps pulling that state and applying it. Changes go through commits and pull requests; nobody runs kubectl apply by hand. The OpenGitOps project defines four principles: declarative, versioned and immutable, pulled automatically, continuously reconciled.

Push-based CI vs GitOps

With Argo CD

An Argo CD Application points at a path in a repository and a destination cluster:

apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: web
  namespace: argocd
spec:
  project: default
  source:
    repoURL: https://github.com/example/deploy.git
    targetRevision: main
    path: apps/web
  destination:
    server: https://kubernetes.default.svc
    namespace: web
  syncPolicy:
    automated:
      prune: true      # delete resources removed from Git
      selfHeal: true   # undo manual changes in the cluster

CI still builds and tests images; the final step updates an image tag in the deploy repository, and Argo CD rolls it out.