GitOps with Argo CD: The Complete Guide

This is for you if

• You know Kubernetes basics and want to run Argo CD as a platform, not just click Sync
• You've inherited an Argo CD install and need to understand why it behaves the way it does
• You're preparing for platform or SRE interviews where GitOps comes up
• You use Flux or push-based CI and want a detailed, honest look at Argo CD

What's inside

• How the reconciliation loop really works: render, diff, health, sync
• Installing Argo CD 3.5 the right way (server-side apply, pinned manifests, HA options)
• Sync policies, drift, self-heal, prune, ignoreDifferences and server-side diff
• Sync phases, waves and hooks for migrations, smoke tests and failure handling
• Helm, Kustomize, multi-source apps and repo layouts that scale
• App of apps, ApplicationSet generators and a two-cluster fan-out on kind
• AppProjects, RBAC, SSO and secrets with Sealed Secrets and External Secrets
• Argo Rollouts canary with automated analysis, plus blue-green
• Notifications, scaling, upgrades, a tested disaster recovery, troubleshooting playbook and cheat sheet

After this guide you can

• Install, configure and upgrade Argo CD 3.x safely, including managing it with itself
• Design a GitOps repo with environment folders, PR-based promotion and ApplicationSets
• Lock down a multi-tenant Argo CD with projects, RBAC, SSO and scoped credentials
• Ship canary and blue-green releases that abort themselves on bad metrics
• Diagnose OutOfSync, stuck syncs and rendering failures quickly
• Rebuild Argo CD from Git and backups after losing its cluster

Contents

1. The GitOps mental modelp. 4
2. Argo CD architecture and installationp. 8
3. Applications, sync policies and driftp. 12
4. Sync phases, waves and hooksp. 20
5. Helm, Kustomize and repo layoutp. 26
6. App of apps, ApplicationSets and multi-clusterp. 32
7. Projects, RBAC, SSO and secretsp. 41
8. Progressive delivery with Argo Rolloutsp. 49
9. Operating Argo CD: notifications, scale, upgrades and recoveryp. 55
10. Troubleshooting playbookp. 63
11. Production checklist and design decisionsp. 66
12. Interview questionsp. 69
13. Cheat sheet and 30-day practice planp. 75