Docker Essentials: A Developer's Practical Guide for 2026

Docker changed how we build and ship software. This guide covers Docker from a developer's perspective — the concepts, commands, and patterns you'll use daily.

Core Concepts

An image is a read-only blueprint. A container is a running instance. A Dockerfile is the recipe. A volume persists data. A network connects containers.

Essential Commands

docker build --tag myapp:latest .
docker run --detach --name myapp --publish 3000:3000 myapp:latest
docker ps
docker logs --follow myapp
docker exec --interactive --tty myapp sh
docker stop myapp && docker rm myapp
docker system prune --all --force

Multi-Stage Builds

Separate the build environment from the runtime for smaller, more secure images.

FROM node:22-alpine AS builder
WORKDIR /app
COPY package.json package-lock.json ./
RUN npm ci
COPY . .
RUN npm run build

FROM node:22-alpine AS runner
WORKDIR /app
ENV NODE_ENV=production
COPY --from=builder /app/dist ./dist
COPY --from=builder /app/package.json ./
RUN npm ci --production --ignore-scripts
USER node
EXPOSE 3000
CMD ["node", "dist/server.js"]

Docker Compose for Local Dev

services:
  app:
    build: .
    ports: ["3000:3000"]
    volumes: [".:/app", "/app/node_modules"]
    depends_on:
      db: { condition: service_healthy }
  db:
    image: postgres:16-alpine
    environment:
      POSTGRES_USER: dev
      POSTGRES_PASSWORD: dev
      POSTGRES_DB: myapp
    healthcheck:
      test: ["CMD-SHELL", "pg_isready -U dev"]
      interval: 5s
      retries: 5

Wrapping Up

Start with a simple Dockerfile and Docker Compose for local dev. Add multi-stage builds for production. The goal: remove environment differences as a source of bugs.