From GitHub Actions to ArgoCD: A Complete GitOps Migration Guide

I've done this migration three times now. Each time, I learn something new about what NOT to do. This guide is the documentation I wish I'd had the first time: the complete migration from a multi-stage GitHub Actions deployment pipeline to a fully declarative GitOps workflow with ArgoCD including the parts every other tutorial glosses over. What you'll build: Production ready ArgoCD installation, ApplicationSet for multi cluster management, Image Updater for automated rollouts, RBAC configuration for multi-team environments, Rollback procedures that work under pressure. Prerequisites: Kubernetes cluster (1.24+), kubectl, Helm 3, existing GitHub Actions CI pipeline. Estimated time: 4-6 hours for learning setup (30 days for production migration). Phase 1: Assessment — Mapping Your Existing GitHub Actions Pipeline Every successful migration begins with clarity. Before introducing GitOps, the existing CI/CD topology must be dissected—methodically, not casually. Start by inventorying workfl