Why Containers?
Containers solve the "works on my machine" problem. They package your application with its dependencies into a consistent, portable unit that runs the same everywhere — your laptop, CI, staging, and production.
Docker Essentials
FROM node:20-alpine
WORKDIR /app
COPY package.json yarn.lock ./
RUN yarn install --frozen-lockfile
COPY . .
RUN yarn build
EXPOSE 3000
CMD ["yarn", "start"]Multi-Stage Builds
Use multi-stage builds to keep your production images lean. Build in one stage, copy only the artifacts you need into the final image. This can reduce image sizes by 80% or more.
Kubernetes Basics
Kubernetes orchestrates containers at scale. It handles deployment, scaling, load balancing, and self-healing. For most teams, managed services like EKS, GKE, or AKS are the way to go — don't run your own control plane unless you have a very good reason.
Local Development
Use Docker Compose for local multi-service setups. Tools like Tilt or Skaffold bridge the gap between local development and Kubernetes deployment, giving you fast feedback loops without sacrificing parity with production.