Using Makefiles to improve Docker image build experience

January 19, 2023

Makefile is a building tool that's been around forever; and while some of us may remember it from building our first couple projects (and may hate those times and the struggle); But I believe it's an awesome tool that by just adding a single file to our project It can speed / easy up our daily work flow on: how we build, run locally, etc our 'Dockerized' projects.

TLDR Github project: https://github.com/danielm/docker-compose-makefiles

Lets suppose that in our project we want:

• Build our docker images
• We have at least 2 environments: production and development
• We want to version our images, we will use Git's commit hashes and environment name: {GITHASH}-{ENVIRNONMENTNAME}.

I like going straight to the point, so lets look at the files we need:

project/
├── docker-compose.yml
├── docker-compose.development.yml
├── docker-compose.production.yml
├── .env
└── Makefile

Nothing special here, a base docker-composer, and the other two to customize/extend each of our environments.

So let's look at our Makefile, you can split it in three points:

1. We include our .env file and then we use some sed magic to export all variables as env (that way those variables will be available to all sub-commands ran by make)
2. Create another env variable, by looking at the current git commit and use it hash.
3. Define all target(make commands) we want to use.

# Include env vars
include .env

# Export them all
export $(shell sed 's/#.*//g; /^$/d; s/=.*//' .env)

# For versioning
TAG_VERSION ?= $(shell git log --format="%h" -n 1)
export TAG_VERSION := $(TAG_VERSION)

# Pattern rule to build environment-specific containers
build:
	docker compose -f docker-compose.yml -f docker-compose.$(ENVIRONMENT).yml build 

# Target to start environment-specific images
up:
	docker compose -f docker-compose.yml -f docker-compose.$(ENVIRONMENT).yml up -d

down:
	docker compose -f docker-compose.yml -f docker-compose.$(ENVIRONMENT).yml down

logs:
	docker compose -f docker-compose.yml -f docker-compose.$(ENVIRONMENT).yml logs -f

push:
	docker push ${DOCKER_REPOSITORY}/${PROJECT_NAME}:${TAG_VERSION}-${ENVIRONMENT}

release:
	docker tag ${DOCKER_REPOSITORY}/${PROJECT_NAME}:${TAG_VERSION}-${ENVIRONMENT} ${DOCKER_REPOSITORY}/${PROJECT_NAME}:latest
	docker push ${DOCKER_REPOSITORY}/${PROJECT_NAME}:latest

Now we have access to these commands:

# Build our image and tags it with: {GITHASH-ENVIRONMENTNAME}
$ make build

# Bings it up
$ make up

# ... and down
$ make down

# Shows log outup
$ make logs

# Push the current tag built by 'build'
$ make push

# Pushes a new tag 'latest' from our current built
$ make release

This was just a simple example on how you could optimize a little bit how you build your projects!

Here is a full project to try it out: https://github.com/danielm/docker-compose-makefiles

Note: Included a NodeJS project (just printing Hello-World) just to demonstrate a full project building flow