docker

Containerize Node.js apps by writing a Dockerfile with a base image, copying application files, installing dependencies, and specifying the startup command. Use multi-stage builds to reduce image size and follow security best practices like running as a non-root user and pinning base image versions for reproducible deployments.

Production Docker deployments require multi-stage builds to minimize image layers, non-root user execution to reduce attack surface, pinned image versions for consistency, .dockerignore configuration to exclude unnecessary files, and layer caching optimization to speed up rebuilds. These practices ensure secure, reproducible, and efficient container images.

Docker Compose orchestrates multi-container applications by defining services—web servers, databases, caches—in a single YAML configuration file. Define each service's image, ports, volumes, and environment variables, then use `docker compose up` to build and run the entire stack locally for consistent development environments.

Docker integrates into CI/CD pipelines to automate building container images, running tests, and pushing images to registries. This enables consistent, reproducible deployment workflows across development, testing, and production environments while reducing manual configuration and environment drift.

Docker images are immutable templates containing application code, dependencies, and runtime configuration; containers are running instances of those images. Images are built from Dockerfiles and stored in registries; containers execute from images and can be started, stopped, and inspected independently.

Optimize Docker builds by leveraging layer caching—order Dockerfile commands so frequently changing layers appear last—using multi-stage builds to exclude build tools from final images, and configuring .dockerignore to exclude unnecessary files. These techniques reduce build time and image size for faster, efficient deployments.