Jonathan Lalou's Blog

Posts Tagged ‘ArgoCD’

TL;DR

Kubernetes may look like an overly complicated version of Docker Compose, but it operates on a different level entirely. Where Compose excels at quick, local orchestration of containers, Kubernetes is a robust, distributed platform designed for automated scaling, fault-tolerance, and production-grade deployments across multi-node clusters. This article provides a comprehensive comparison and shows how ArgoCD enhances GitOps-based Kubernetes workflows.

Docker Compose vs Kubernetes – Similarities and First Impressions

At a high level, Docker Compose and Kubernetes share similar concepts: containers, services, configuration, and volumes. This often leads to the assumption that Kubernetes is just a verbose, harder-to-write Compose replacement. However, Kubernetes is more than a runtime. It’s a control plane, a state manager, and a policy enforcer.

Real-Life Use Cases – Docker Compose vs Kubernetes Examples

Tomcat + Oracle + MongoDB + NGINX Stack

Docker Compose

version: '3'
services:
  nginx:
    image: nginx:latest
    ports:
      - "80:80"
    depends_on:
      - tomcat

  tomcat:
    image: tomcat:9
    ports:
      - "8080:8080"
    environment:
      DB_URL: jdbc:oracle:thin:@oracle:1521:orcl

  oracle:
    image: oracle/database:19.3.0-ee
    environment:
      ORACLE_PWD: secretpass
    volumes:
      - oracle-data:/opt/oracle/oradata

  mongo:
    image: mongo:5
    volumes:
      - mongo-data:/data/db

volumes:
  oracle-data:
  mongo-data:

Kubernetes Equivalent

• Each service becomes a Deployment and a Service.
• Environment variables and passwords are stored in Secrets.
• Volumes are defined with PVC and StorageClass.

apiVersion: v1
kind: Secret
metadata:
  name: oracle-secret
type: Opaque
data:
  ORACLE_PWD: c2VjcmV0cGFzcw==

---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: tomcat
spec:
  replicas: 2
  selector:
    matchLabels:
      app: tomcat
  template:
    metadata:
      labels:
        app: tomcat
    spec:
      containers:
      - name: tomcat
        image: tomcat:9
        ports:
        - containerPort: 8080
        env:
        - name: DB_URL
          value: jdbc:oracle:thin:@oracle:1521:orcl

NodeJS + Express + MySQL + NGINX

Docker Compose

services:
  mysql:
    image: mysql:8
    environment:
      MYSQL_ROOT_PASSWORD: rootpass
    volumes:
      - mysql-data:/var/lib/mysql

  api:
    build: ./api
    environment:
      DB_USER: root
      DB_PASS: rootpass
      DB_HOST: mysql

  nginx:
    image: nginx:latest
    ports:
      - "80:80"

Kubernetes Equivalent

apiVersion: v1
kind: Secret
metadata:
  name: mysql-secret
type: Opaque
data:
  MYSQL_ROOT_PASSWORD: cm9vdHBhc3M=
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: api
spec:
  replicas: 2
  template:
    spec:
      containers:
      - name: api
        image: node-app:latest
        env:
        - name: DB_PASS
          valueFrom:
            secretKeyRef:
              name: mysql-secret
              key: MYSQL_ROOT_PASSWORD

⚙️ Docker Compose vs kubectl – Command Mapping

ArgoCD – GitOps Made Practical

ArgoCD is a Kubernetes-native continuous deployment tool. It uses Git as the single source of truth, enabling declarative infrastructure and GitOps workflows.

✨ Key Features

• Declarative sync of Git and cluster state
• Drift detection and automatic repair
• Multi-environment and multi-namespace support
• CLI and Web UI available

Example ArgoCD Commands

argocd login argocd.myorg.com
argocd app create my-app \
  --repo https://github.com/org/app.git \
  --path k8s \
  --dest-server https://kubernetes.default.svc \
  --dest-namespace production

argocd app sync my-app
argocd app get my-app
argocd app diff my-app

Sample ArgoCD Application Manifest

apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: my-api
spec:
  destination:
    namespace: default
    server: https://kubernetes.default.svc
  project: default
  source:
    path: k8s/app
    repoURL: https://github.com/org/api.git
    targetRevision: HEAD
  syncPolicy:
    automated:
      prune: true
      selfHeal: true

✅ Conclusion

Docker Compose is perfect for prototyping and local dev. Kubernetes is built for cloud-native workloads, distributed systems, and high availability. ArgoCD makes declarative, Git-based continuous deployment simple, scalable, and observable.