Docker Tip #62: Using 2 Dockerfiles in the Same Compose Project
This use case comes up often if you work on a project where you need a separate Dockerfile for your back-end and front-end.
A prime example would be let’s say you had your back-end written in Python, Node, Ruby, Elixir or any language you prefer.
But then to deal with your front-end assets you are using Webpack (or similar).
It’s a reasonable idea to keep both of these as separate Docker images. Especially since Webpack in development will likely involve setting up a watcher service so you don’t need to keep re-building your assets on every change.
That means we have 2 separate processes, so running 2 containers is a good idea.
A Docker Compose snippet of using (2) Dockerfiles for (2) different services:
services:
webpack:
build:
context: "."
dockerfile: "Dockerfile.webpack"
web:
build: "."
In the web case it just uses our Dockerfile in the root of the directory but then in the webpack case it looks for Dockerfile.webpack instead.
A fully working example can be found in the Docker best practices example repo that has a few web framework examples.
A variant of this set up would be to set the context to ./assets and put a Dockerfile in there instead of using a different Dockerfile filename but personally I like it when all of my Docker related files are in the same directory.