docker

Building a Docker container involves writing a Dockerfile with your application's dependencies, running `docker build` to create an image, then `docker run` to execute it. The Dockerfile specifies the base image, installs requirements, and sets the entry point; `docker build` layers these instructions into a reusable image, and `docker run` starts a container instance with exposed ports and environment configuration.

Efficient Dockerfiles use multi-stage builds to reduce final image size, order instructions from least to most frequently changed for layer caching, minimize layer count, and run containers as non-root users for security. Multi-stage builds compile dependencies in earlier stages and copy only artifacts to the final stage, dramatically reducing image bloat while maintaining reproducibility.

Yes, Docker supports multi-platform builds targeting architectures like `linux/amd64` and `linux/arm64`. Use `docker buildx` with `--platform` flags to create images compatible across different hardware, enabling seamless deployment on diverse environments from cloud servers to edge devices and Raspberry Pi.

Container lifecycle management includes defining health checks in your Dockerfile or `docker-compose`, using `docker logs` to inspect output, `docker exec` to run commands inside running containers, and `docker inspect` to examine container state. Health checks enable automatic restart policies, and logging provides visibility into application behavior and troubleshooting.

A Docker image is a read-only template containing your application, dependencies, and configuration; a container is a running instance of that image with its own isolated filesystem and process space. Images are built once and reused; containers are ephemeral runtime environments created from images and can be started, stopped, and discarded.

Use `docker prune` commands to remove unused images, containers, and networks: `docker image prune` removes dangling images, `docker container prune` removes stopped containers, and `docker system prune` cleans all unused resources. This reclaims disk space and keeps your Docker environment organized for efficient workflows.