Docker: simplifying your application deployment

Hook

Docker lets you bundle your application and all its dependencies into a single isolated image. That means your code runs the same everywhere without the classic “it works on my machine” headaches.

Problem / Context

Before containers, deploying meant installing various software on each server, handling library versions, and dealing with incompatibilities. The result – environments diverge and releases break.

Why it matters

Containers give you stability, fast scaling, and simplify CI/CD pipelines. You save time on environment setup and reduce the risk of production bugs.

How to do it

1. Install Docker Engine

   sudo apt‑update
   sudo apt‑install -y ca-certificates curl gnupg
   sudo mkdir -p /etc/apt/keyrings
   curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /etc/apt/keyrings/docker.gpg
   echo "deb [arch=$(dpkg --print-architecture) signed‑by=/etc/apt/keyrings/docker.gpg] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
   sudo apt‑update
   sudo apt‑install -y docker-ce docker-ce-cli containerd.io docker-compose-plugin

2. Verify the installation

   docker run --rm hello-world

3. Create a Dockerfile for a simple Node.js app:

   FROM node:18-alpine
   WORKDIR /app
   COPY package*.json ./
   RUN npm ci --only=production
   COPY . .
   CMD ["node", "index.js"]

4. Build the image

   docker build -t my‑app .

5. Run the container

   docker run -d -p 3000:3000 --name my‑app‑c my‑app

   Your app is now reachable at http://localhost:3000.

Anti‑patterns

• Running the container as root – create a non‑root user inside the image.
• Skipping EXPOSE – makes it harder to see which ports are intended.
• Using heavyweight base images – prefer Alpine‑based images to keep the size small.

Conclusion / Action plan

• Install Docker on your machine.
• Write a simple Dockerfile for one of your projects.
• Add Docker commands to your CI pipeline.
• After a successful run, explore docker‑compose for multi‑container setups.