Posted on June 23, 2025June 23, 2025 | by priteshgeek

📘 1. Introduction & Overview

🔹 What is ArgoCD?

ArgoCD is a declarative, GitOps continuous delivery tool for Kubernetes. It synchronizes your Kubernetes clusters with configurations stored in a Git repository, ensuring that your desired application state defined in Git matches the actual deployed state.

Think of ArgoCD as a Kubernetes-native GitOps controller that watches your Git repositories and automatically applies updates to clusters in a secure, auditable, and automated way.

🔹 History and Background

Developed by Intuit and now a CNCF graduated project.
First released in 2018.
Evolved rapidly to become a core component in GitOps-based Kubernetes delivery pipelines.

🔹 Why is ArgoCD Relevant in DevSecOps?

DevSecOps emphasizes integrating security at every phase of the DevOps lifecycle. ArgoCD plays a crucial role by:

Enforcing immutable infrastructure using Git.
Maintaining audit trails through Git commits.
Supporting RBAC and SSO for secure access control.
Enabling policy-as-code and compliance automation.
Providing visibility and control over the deployment process.

📚 2. Core Concepts & Terminology

🔑 Key Terms and Definitions

Term	Definition
GitOps	Managing infrastructure and app delivery via Git as the single source of truth.
Declarative	Infrastructure described as code, not as scripts.
Application	ArgoCD resource mapping Git repos to Kubernetes manifests.
Sync	Matching actual cluster state to desired state defined in Git.
Drift	When actual cluster state deviates from Git.

🔄 How ArgoCD Fits into DevSecOps Lifecycle

DevSecOps Stage	ArgoCD Role
Plan	Manifests and policies are versioned in Git
Develop	Dev teams push Helm/Kustomize/Manifest configs to Git
Build	CI pipelines validate and lint configs before commit
Test	Security scanners check YAMLs; policies validated pre-deploy
Release	ArgoCD syncs to production automatically or manually
Deploy	Git-driven, secure, observable deployments
Operate	Drift detection, health monitoring, automated rollback

🏗️ 3. Architecture & How It Works

🔧 Core Components

Component	Description
API Server	Exposes REST/GRPC interface to UI/CLI tools.
Repository Server	Clones and reads Git repositories.
Controller	Monitors apps and performs synchronization.
Application CRD	Kubernetes custom resource that defines an app, its Git source, and sync rules.

🔁 Internal Workflow

Git repository is configured with Kubernetes manifests.
ArgoCD registers an Application CRD pointing to the Git path.
ArgoCD periodically pulls changes and compares with live cluster state.
If drift is detected, it auto-syncs or alerts (based on policy).
Users get real-time status via the ArgoCD UI/CLI.

🧱 Architecture Diagram (Descriptive)

[Textual Representation]

+---------+        +-----------------+       +--------------+
|  DevOps |------->| Git Repository  |<----->| CI Pipeline  |
+---------+        +--------+--------+       +--------------+
                            |
                            v
                  +-------------------+
                  |   ArgoCD Server   |
                  +--------+----------+
                           |
        +------------------+-------------------+
        |                                      |
+-------------------+               +--------------------+
| Kubernetes Cluster|<---Sync-----> | Application State  |
+-------------------+               +--------------------+

🔗 Integration with CI/CD & Cloud

CI Tools: Jenkins, GitHub Actions, GitLab CI can trigger commits.
Security Tools: Integrate OPA/Gatekeeper, Kyverno for policies.
Cloud: Works on AWS, Azure, GCP, EKS, AKS, GKE, etc.

⚙️ 4. Installation & Getting Started

📋 Prerequisites

Kubernetes cluster (Minikube, EKS, GKE, etc.)
kubectl and argocd CLI
Git repository with manifests (Helm, Kustomize, or plain YAML)

🛠️ Step-by-Step Setup Guide

🧪 Step 1: Install ArgoCD

kubectl create namespace argocd

kubectl apply -n argocd -f https://raw.githubusercontent.com/argoproj/argo-cd/stable/manifests/install.yaml

🔐 Step 2: Access ArgoCD UI

kubectl port-forward svc/argocd-server -n argocd 8080:443

Go to https://localhost:8080.
Login using:

username: admin
password: <from secret>
kubectl get secret argocd-initial-admin-secret -n argocd -o yaml

📥 Step 3: Create a Sample Application

argocd login localhost:8080

argocd app create guestbook \
--repo https://github.com/argoproj/argocd-example-apps.git \
--path guestbook \
--dest-server https://kubernetes.default.svc \
--dest-namespace default

🔄 Step 4: Sync the App

argocd app sync guestbook
argocd app list

🌍 5. Real-World Use Cases

✅ Use Case 1: Secure Deployments with Git Commit Triggers

All changes must go via Git pull requests.
ArgoCD auto-syncs on merge.
Ensures audit trails and rollback capability.

✅ Use Case 2: Multi-Cluster Governance

One ArgoCD instance managing 10+ clusters.
RBAC per team, per environment.
Used in fintech or banking for compliance.

✅ Use Case 3: DR/HA Environments

DR clusters auto-synced with prod via ArgoCD.
Ensures minimal drift and high availability.

✅ Use Case 4: Healthcare App Delivery

Helm charts + ArgoCD for EMR system deployment.
Compliance with HIPAA via audit and rollback.

✅ 6. Benefits & Limitations

🎯 Benefits

Secure GitOps with RBAC and Git auditability.
Self-healing: Syncs and alerts on drift.
Kubernetes-native and declarative.
Integrates well with Helm, Kustomize, SSO.

⚠️ Limitations

Learning curve for custom sync hooks.
Complex in multi-tenant environments without best practices.
Large-scale Git repos may slow down performance.

💡 7. Best Practices & Recommendations

🔐 Security & Compliance

Enable SSO and RBAC.
Use GPG-signed commits.
Integrate OPA/Gatekeeper for policy checks.

⚙️ Automation Tips

Auto-sync with manual approval for production.
Use GitHub Actions for CI + ArgoCD for CD.
Monitor with Prometheus + Grafana integration.

🆚 8. Comparison with Alternatives

Feature	ArgoCD	FluxCD	Spinnaker	Jenkins X
GitOps Native	✅	✅	❌	✅
UI Dashboard	✅	❌ (CLI only)	✅	✅
Multi-cluster	✅	✅	✅	❌
Sync Policies	✅	Limited	❌	✅
Declarative Setup	✅	✅	❌	✅

Choose ArgoCD when:

You need Kubernetes-native GitOps
You require visual observability
You want strong RBAC, auditing, and policy enforcement

🏁 9. Conclusion

ArgoCD empowers DevSecOps teams with secure, auditable, declarative application delivery. Its GitOps model reduces drift, improves compliance, and accelerates deployments — making it ideal for regulated industries, large enterprises, and modern DevOps pipelines.

ArgoCD in DevSecOps: A Comprehensive Guide