homelab/GITOPS_IMPLEMENTATION_SUMMARY.md

GitOps IaC Implementation Summary

Documents Created

1. GITOPS_ARCHITECTURE.md - Production-grade directory structure & design
2. GITOPS_MIGRATION_PLAN.md - Step-by-step implementation (6 weeks, non-disruptive)

Architecture at a Glance

Pure GitOps (ArgoCD only, no Terraform)
├── Layer 0: Infrastructure (namespaces, storage, RBAC)
├── Layer 1: Bootstrap (cert-manager, cilium, ingress-nginx)
├── Layer 2: Platform (minio, longhorn, loki, prometheus)
├── Layer 3: Security (authentik, vault)
├── Layer 4: Applications (forgejo, grafana, portainer, temporal, llm)
└── Layer 5: Data (postgres, redis, kafka)

Key benefit: Each layer depends on previous, staged deployment, easy rollback.

File Structure

k8s/
├── _base/                    # Shared kustomization base
├── infrastructure/           # Layer 0 (foundation)
├── bootstrap/               # Layer 1 (networking)
├── platform/                # Layer 2 (services)
├── security/                # Layer 3 (auth)
├── applications/            # Layer 4 (business logic)
├── data/                    # Layer 5 (stateful)
└── argocd/
    ├── projects/            # AppProject definitions
    └── apps/
        ├── root-app.yaml    # Bootstraps Layer 0
        └── layer-*.yaml     # 5 layer apps (synced in order)

Implementation Steps

Phase 1: Plan (Week 1)

• Review GITOPS_ARCHITECTURE.md
• Review GITOPS_MIGRATION_PLAN.md
• Audit current cluster resources
• Identify secrets needing encryption (SOPS)
• Map dependencies (provided in plan)
• User approval required before proceeding to Phase 2

Phase 2: Build (Weeks 2-3)

• Create k8s/ directory structure
• Migrate Layer 0 (infrastructure)
• Migrate Layer 1 (bootstrap: cert-manager, cilium, ingress-nginx)
• Migrate Layer 2 (platform: minio, longhorn, loki, prometheus)
• Migrate Layer 3 (security: authentik, vault)
• Migrate Layer 4 (applications: forgejo, grafana, temporal, etc.)
• Migrate Layer 5 (data: postgres, redis, kafka)

Phase 3: ArgoCD (Week 4)

• Create root application (Layer 0 trigger)
• Create 5 layer applications (with sync-wave ordering)
• Update AppProject permissions
• Test dry-run on each layer

Phase 4: Deploy (Week 5)

• Pre-flight validation (kustomize build, kubeval, yamllint)
• Deploy root application
• Deploy layer applications (one by one)
• Monitor for drift
• Verify state correction (manual edits reverted)

Phase 5: Cleanup (Week 6)

• Delete old k8s/ directories
• Update CI/CD pipeline (remove terraform, add kustomize)
• Archive legacy configuration
• Final validation

Key Architecture Decisions

✓ Why Layers?

• Clear dependencies: Layer N can't deploy until Layer N-1 succeeds
• Easy debugging: Which layer broke? Layer 2? Roll back Layer 2 only.
• Easy scaling: Add new service without touching others
• Easy rollback: git revert <layer-commit>

✓ Why Kustomize?

• Helm chart package + values override (clean separation)
• Kustomize build validates before sync
• Patches enable per-environment customization
• Standard K8s tool (no external dependencies)

✓ Why No Terraform?

• Single tool (ArgoCD) vs. dual tool (Terraform + ArgoCD)
• Git is source of truth for everything
• No state backend (no .tfstate files)
• ArgoCD continuous reconciliation (drift auto-corrected)
• All changes reviewed in PRs (audit trail in git)

✓ Why This File Structure?

• Predictable: Each service has consistent structure (kustomization.yaml, values.yaml, config/)
• Scalable: New service = new directory (copy template)
• Maintainable: Clear ownership (who owns layer? who owns service?)
• GitOps-ready: Each layer is independently deployable

Secret Management (SOPS)

Before (Terraform)

terraform/terraform.tfvars     # Plaintext secrets (risky!)

After (GitOps)

# Encrypt secrets before commit
sops -e secrets.yaml > secrets.enc.yaml
git add secrets.enc.yaml

# ArgoCD decrypts at sync time (SOPS plugin installed)
# Git stores only encrypted version (safe)

Secrets to encrypt:

• Authentik bootstrap password
• MinIO root credentials
• Database passwords
• API tokens
• OAuth client secrets

CI/CD Integration

Before

git push → terraform validate → terraform plan → manual apply

After (Pure GitOps)

git push → yamllint → kubeval → kustomize build → argocd validation
                                                      ↓
                                        ArgoCD auto-syncs (if PR merged)

No manual steps. No terraform. No state management. Pure GitOps.

Comparison: Old vs. New

Aspect	Old (Terraform + ArgoCD)	New (ArgoCD Only)
State management	tfstate files	Git history
Secrets	Plaintext in .tfvars	SOPS encrypted
Manual steps	terraform apply required	git push only
Rollback	Revert tfstate + code	git revert + push
Audit trail	Terraform logs	Git history + ArgoCD logs
Complexity	High (2 tools)	Low (1 tool)
New services	Edit .tf files	Copy service directory
State drift	Manual terraform plan to detect	ArgoCD auto-detects & corrects

Non-Disruptive Migration

Key principle: Live cluster remains running during entire migration.

How?

1. Build k8s/ structure alongside existing configuration
2. Deploy each layer via ArgoCD while old method still runs
3. Once new layer verified: delete old configuration
4. If issue detected: rollback (git revert) + redeploy old version

Timeline: 6 weeks (can be parallelized to 3-4 weeks if needed)

Rollback Procedure (At Any Point)

# 1. Identify broken layer
argocd app get layer-2-platform  # Shows OutOfSync, error

# 2. Revert that layer
git revert <commit-hash>
git push

# 3. ArgoCD detects change, syncs back to previous version
# Expected: ~3 minutes for full reconciliation

# 4. Verify
argocd app get layer-2-platform  # Should be Synced again

Day 1 Action Items

1. Read GITOPS_ARCHITECTURE.md (30 min)

   • Understand layers
   • Understand directory structure
   • Understand kustomization strategy

2. Read GITOPS_MIGRATION_PLAN.md (30 min)

   • Understand phases
   • Understand timeline
   • Understand success criteria

3. Review dependency map (provided in plan)

   • Confirm layer dependencies match current setup
   • Identify any services not in layers

4. Audit secrets (30 min)

   grep -r "password" k8s/ --include="*.yaml"
   grep -r "token" k8s/ --include="*.yaml"
   # Plan which need SOPS encryption
   

5. Decision point: Proceed to Phase 2 (Week 2)?

   • YES → Start building k8s/ structure
   • NO → Clarify concerns, refine plan

Benefits Summary

✓ Simpler: One tool (ArgoCD), one repo (git), one source of truth ✓ Safer: All changes reviewed in PRs, git history as audit trail ✓ Scalable: New services = copy directory, update git, done ✓ Resilient: State drift auto-corrected, rollback via git revert ✓ Auditable: Every change in git with who/when/why ✓ Automated: No manual kubectl apply, no manual terraform apply ✓ Testable: Kustomize build validates before sync ✓ Recoverable: git history = disaster recovery

Support

• Architecture questions → GITOPS_ARCHITECTURE.md
• Implementation questions → GITOPS_MIGRATION_PLAN.md
• Syntax/tools questions → See referenced documentation
  • Kustomize: https://kustomize.io/
  • ArgoCD: https://argo-cd.readthedocs.io/
  • SOPS: https://github.com/mozilla/sops

Next Steps

1. User review: Read both architecture documents (60 min)
2. User decision: Proceed to Phase 2 or refine plan?
3. Kickoff Phase 2: Start building infrastructure layer (Week 2 Monday)

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Status: Ready for implementation Terraform: Deleted ✓ Architecture: Designed ✓ Plan: Ready ✓ Waiting for: User approval to proceed