Docker has become a standard tool in every DevOps engineer’s toolkit. Whether you’re building microservices or deploying scalable containers, understanding how Docker works — and how to use it efficiently — is essential.
In this blog, we’ll explore what Docker is, how it helps DevOps workflows, and go through the most commonly used Docker commands with examples.
🐳 What is Docker?
Docker is an open-source platform that allows developers and DevOps engineers to package applications into containers — lightweight, standalone, and executable units that include everything the app needs to run.
Instead of “it works on my machine,” with Docker, it works everywhere — from your laptop to production.
🔧 Why Use Docker in DevOps?
✅ Portability: Containers run the same on every environment
✅ Speed: Build and deploy apps faster
✅ Isolation: Each container runs in its own environment
✅ CI/CD Ready: Ideal for automated pipelines
🛠️ Essential Docker Commands
Here are the most commonly used Docker commands you’ll use daily:
🔹 1. Check Docker Version
docker --version
🔹 2. Pull an Image from Docker Hub
docker pull nginx
This downloads the latest official Nginx image.
🔹 3. List Available Docker Images
docker images
🔹 4. Run a Container
docker run -d -p 8080:80 nginx
Runs Nginx in detached mode, mapping port 80 inside the container to port 8080 on your system.
🔹 5. List Running Containers
docker ps
Use
docker ps -ato see all (including stopped) containers.
🔹 6. Stop a Container
docker stop <container_id>
🔹 7. Remove a Container
docker rm <container_id>
🔹 8. Build a Docker Image from Dockerfile
docker build -t myapp:1.0 .
This command builds a Docker image with a tag
myapp:1.0.
🔹 9. Tag and Push Image to Docker Hub
docker tag myapp:1.0 yourdockerhub/myapp:1.0
docker push yourdockerhub/myapp:1.0
🔹 10. View Logs from a Running Container
docker logs <container_id>
📁 Bonus: Dockerfile Example
Here’s a simple Dockerfile for a Node.js app:
FROM node:18
WORKDIR /app
COPY package*.json ./
RUN npm install
COPY . .
CMD ["npm", "start"]
🚀 Real-Life DevOps Use Case
Let’s say you’re deploying a Python Flask app. With Docker, you:
- Package the app with all dependencies
- Build an image and push to Docker Hub
- Deploy that image using Jenkins, ECS, or Kubernetes
Result: No “dependency hell” across dev, QA, or prod.
🧠 Conclusion
Docker is essential for DevOps engineers. With just a few commands, you can build, test, deploy, and scale apps in seconds.
In the next blog, we’ll explore Docker Compose to manage multi-container applications easily.