DevOps Sector Blueprint

GitOps

Declarative Infrastructure, Pull-Based Reconciliation & ArgoCD

GitOps uses Git repositories as the single source of truth for infrastructure and application declarations. Automated operators (such as ArgoCD) continuously reconcile the desired state in Git with the live cluster state.

Operational Philosophy:“If it is not in Git, it does not exist. All changes—from replica counts to ingress routing—must be made through pull requests, creating a complete, audited, reproducible commit history.”

Architecture & Pipeline Stages

Standard Delivery Lifecycle

Sequential stages, responsibilities, and tooling required to implement GitOps.

01. STAGE

Declarative Manifests in Git

Helm charts, Kustomize overlays, or raw YAML tracking desired Kubernetes resources.

Key Tools

GitHelmKustomize

02. STAGE

GitOps Operator In-Cluster

Continuous synchronization loop comparing Git commits against live cluster API.

Key Tools

ArgoCDFlux CD

03. STAGE

Automated Self-Healing

Reverting unauthorized manual kubectl edits back to the version declared in Git.

Key Tools

ArgoCD Auto-SyncSelfHeal Controller

04. STAGE

Progressive Delivery & Rollback

Canary rollouts, traffic shifting, and instant rollbacks on metric anomalies.

Key Tools

Argo RolloutsPrometheus Metrics

Troubleshooting & Battle-Tested Fixes

Real-World Challenges & Solutions

Practical issues encountered in production, root-cause analyses, and concrete code/configuration fixes.

Symptom / Error Indicator

ArgoCD marks resources as OutOfSync immediately after deployment, triggering continuous sync loops.

Root Cause

Kubernetes mutating admission webhooks (like cert-manager, Istio sidecars, or HPA replica count) alter fields that Git does not specify.

Resolution Procedure

Add `ignoreDifferences` in the ArgoCD Application manifest for dynamic runtime fields (such as `.spec.replicas` or metadata annotations).

yaml

spec:
  ignoreDifferences:
  - group: apps
    kind: Deployment
    jsonPointers:
    - /spec/replicas
  - group: ""
    kind: Secret
    name: my-dynamic-secret
    jsonPointers:
    - /data

Long-term Prevention: Avoid defining static replica counts in Git if an HPA (Horizontal Pod Autoscaler) is managing pod counts.

Technology Selection

Industry Tooling Matrix

Comparison of enterprise industry leaders and battle-tested open-source self-hosted alternatives.

Domain Category	Industry Leaders	Open Source / Self-Hosted	Evaluation Criteria
GitOps Continuous Delivery	ArgoCDFlux CD	ArgoCDFlux v2Fleet	Multi-cluster management, Web UI clarity, SSO integration, RBAC, helm support.
Manifest Templating	HelmKustomize	HelmKustomizejsonnetTimoni	Packaging simplicity, community ecosystem, schema validation, values override clarity.
Progressive Delivery	Argo RolloutsFlagger	Argo RolloutsFlagger	Ingress controller integration, automated analysis templates, webhooks.

Architecture Checklist

Recommended Best Practices

Foundational rules for sustainable, resilient, and secure operations.

Always enable self-healing (`selfHeal: true`) and pruning (`prune: true`) in ArgoCD for true state enforcement.

Keep application source code and deployment manifests in decoupled or distinct directories.

Protect main branches with required code reviews and automated CI validation checks.

Store secrets encrypted in Git using SOPS, SealedSecrets, or fetch from external vaults at pod startup.

← Previous SectorDevSecOpsShift-Left Security, Automated Compliance & Vulnerability Management Next Sector →MLOpsMachine Learning Lifecycle, Model Registries & Drift Detection