Docker Tutorials & Guides
Docker packages an application and its dependencies into a portable container image that runs the same on a laptop, a CI runner, or a production server. These guides walk through writing Dockerfiles, building and tagging images, running containers, and pushing to a registry — then move into the practices that matter at scale: multi-stage builds, small and secure base images, layer caching, and healthchecks.
A container is not a virtual machine — it's an isolated process using Linux kernel features (namespaces and cgroups) that shares the host kernel. Understanding that model is what makes the difference between images that are fast and lean and ones that are bloated and slow.
Frequently asked questions
What is Docker and why is it used?
Docker is a tool for building and running containers — lightweight, isolated environments that bundle an app with its dependencies. It's used to eliminate 'works on my machine' problems, ship consistent builds through CI/CD, and run services reproducibly across environments.
What is the difference between a Docker image and a container?
An image is a read-only template (the built artifact); a container is a running instance of an image. You build an image once and can run many containers from it.
What is a multi-stage Docker build?
A multi-stage build uses multiple FROM stages in one Dockerfile so build-time tools (compilers, dev dependencies) stay out of the final image. You compile in an early stage and copy only the built artifacts into a small runtime stage, producing a much smaller, more secure image.
