GitOps the Hard Way, with Argo CD

What You Will Learn

By the end of this book you will have built a full GitOps setup from nothing and operated it, not read about it. Concretely, you will be able to:

• Explain what Argo CD does and does not do, and trace a change from a Git commit through the reconciliation loop to a running resource on the cluster.

• Name the parts that make up Argo CD, the API server, application controller, repo-server, Redis, Dex, the ApplicationSet controller, and say what breaks when each one is unhealthy.

• Provision real infrastructure from scratch: stand up servers with Terraform, bootstrap a Kubernetes cluster, and deploy an application onto it, so Argo CD has something real to manage.

• Install Argo CD and choose deliberately between the full, core, and custom installs, then log in from the CLI and register additional clusters.

• Create your first Application from the argocd CLI, then redefine the exact same setup as declarative manifests you keep in Git, including the repository credentials.

• Read an Application manifest field by field, and configure sync policy on purpose: automated sync, self-healing, pruning and its exceptions, retries and backoff, ignoreDifferences, namespace creation, and the sync options that change how Argo CD applies resources.