Argo CD
Argo CD is a declarative continuous delivery tool for Kubernetes. It runs inside the cluster, watches a Git repository that holds the desired manifests, and compares them with the live resources. When they differ, it reports the application as out of sync and can apply the Git version.
How it works
You define an Application that points at a repo path and a target cluster and namespace. Argo CD polls the repo every 3 minutes by default, or reacts sooner to a webhook, and renders plain YAML, a Helm chart or Kustomize.
For example, a commit changes an image tag from v1.4.2 to v1.4.3. The app turns OutOfSync, then Synced after the sync. If someone later runs kubectl scale by hand, self-heal reverts the replica count to what Git says.
Why it matters in production
CI no longer needs cluster credentials, because the agent pulls changes in. Rollback is a Git revert, and the history shows who changed what. It is the pull-based agent behind GitOps. Secrets, pruning rules and sync order still need planning, or automated sync will surprise you.
See also
On the One2N blog
Further reading
