Docker for Developers: From Development to Production

Why Docker

Docker eliminates the "works on my machine" problem. Every developer on your team runs the same environment. Your CI/CD pipeline builds once and deploys everywhere. Production matches development.

Essential Docker Concepts

Images

Read-only templates containing your application code, runtime, libraries, and dependencies. Think of them as snapshots of your application.

Containers

Running instances of images. Containers are lightweight, isolated, and disposable. Start one in seconds, stop it without affecting others.

Dockerfile

A text file containing instructions to build your image. Each instruction creates a layer in the image. Understanding layer caching is key to building efficient Dockerfiles.

Writing Better Dockerfiles

Use Multi-Stage Builds

Separate your build environment from your runtime. This reduces image size dramatically:

# Build stage
FROM node:20 AS builder
WORKDIR /app
COPY . .
RUN npm ci && npm run build

# Runtime stage
FROM node:20-slim
COPY --from=builder /app/dist ./dist
CMD ["node", "dist/index.js"]

Leverage Layer Caching

Order your Dockerfile instructions from least to most frequently changing. Dependencies rarely change — copy and install them before copying your source code.

Use .dockerignore

Exclude unnecessary files from your build context. Node modules, git directories, and documentation shouldn't be in your image.

Docker Compose for Development

Docker Compose lets you define multi-service environments in a single file:

services:
  app:
    build: .
    ports:
      - "3000:3000"
    depends_on:
      - database
      - redis
  database:
    image: postgres:16
    volumes:
      - pgdata:/var/lib/postgresql/data
  redis:
    image: redis:7

One command starts your entire development environment — application, database, cache, and any other services.

Production Deployment

Health Checks

Always define health checks in your Dockerfile or Compose file. This allows orchestrators to restart unhealthy containers automatically.

Resource Limits

Set memory and CPU limits. Prevent one container from consuming all resources and affecting others.

Logging

Write logs to stdout/stderr. Let Docker handle log collection and rotation. This works with any container orchestration platform.

CI/CD Integration

Build images in your CI pipeline, tag them with the commit SHA, and push to a container registry. Deploy by pulling the new image and restarting the container. Rollbacks become as simple as deploying the previous tag.