Dockerfile

A common mistake is shipping your entire build environment — compilers, package managers, SDKs — in your production Docker image. A Go application needs the Go compiler to build. But once it is built, the binary runs without Go installed at all. Why include 1 GB of Go tooling in an image that only needs a 10 MB binary? Multi-stage builds solve this. They let you compile your app in one container and copy only the final artifact into a minimal production image. ...

A Dockerfile is a text file with instructions that tell Docker how to build your image. Every Docker image — from nginx to postgres to your own app — starts with a Dockerfile. In this tutorial, you will learn every key Dockerfile instruction and write a complete, production-ready Dockerfile. Dockerfile Basics A Dockerfile is a plain text file named Dockerfile (no extension). Docker reads it top to bottom when building an image. Each instruction creates a new layer. ...

In the previous tutorial, we ran containers from pre-built images like ubuntu and nginx. That is useful, but in real projects you need to package your own application into an image. That is what a Dockerfile does. A Dockerfile is a text file with instructions that tell Docker how to build an image. Think of it as a recipe — each line is a step. Your First Dockerfile Let’s create a simple Node.js application and package it with Docker. ...