(Ab)using Makefiles in Django projects

Makefile

# Lightning talk @ DjangoCon EU 2022
# Afonso Cerejeira <github.com/ajcerejeira>

# Intro
# =====
#
# - Makefiles are a set of rules for building targets based on prerequisites;
# - Usually both targets and prerequisites represent filenames;
# - Makefiles define dependency graphs;


# Project setup
# =============

VENV   := .venv
PYTHON := $(VENV)/bin/python

$(PYTHON):
	python -m venv $(VENV)

.PHONY: install
install: $(VENV)/.install

$(VENV)/.install: $(PYTHON) requirements.txt
	$(PYTHON) -m pip install -r requirements.txt
	touch $@	# file name of the target of the rule, in this case '.venv/.install'

# Usage:
#
# $ make install
# python -m venv .venv
# .venv/bin/python -m pip install -r requirements.txt
# ...
# touch .venv/.install
#
# make only runs install when requirements.txt is updated:


# Automatically installing Python programs
# ========================================

# Special rule to automatically install binary targets, (e.g, dev tools)
# - '%' is a placeholder to be substituted in the target
# - '$@' expands to the name of the target (i.e, '$(VENV)/bin/...')
# - 'notdir' is function that extracts the basename of a file
$(VENV)/bin/%: $(PYTHON)
	$(PYTHON) -m pip install $(notdir $@)

# Usage:
# $ make .venv/bin/pylint
# python -m venv .venv
# .venv/bin/python -m pip install pylint
# Collecting pylint

# Linting and formatting
# ======================

BLACK  := $(VENV)/bin/black
ISORT  := $(VENV)/bin/isort
DJHTML := $(VENV)/bin/djhtml
PYLINT := $(VENV)/bin/pylint

.PHONY: format
format: $(BLACK) $(ISORT) $(DJHTML)
	$(BLACK) .
	$(ISORT) .
	$(DJHTML) -i templates/

.PHONY: lint
lint: $(PYLINT)
	$(PYLINT) .


# Testing
# =======

COVERAGE := $(VENV)/bin/coverage

.PHONY: test
test: install $(COVERAGE)
	$(COVERAGE) run manage.py test
	$(COVERAGE) report
	$(COVERAGE) html


# Automating Docker workflows
# ===========================

.ONESHELL: docker
.SILENT: docker
docker: .SHELLFLAGS = run --rm --entrypoint /bin/bash ubuntu -c
docker: SHELL := docker
docker:
	echo "hello, container world!"


# Embedding Python scripts in the Makefile
# ========================================

# Generate secret key

# Run all the commands of target 'secretkey' in a single shell
.ONESHELL: secretkey

# Do not print the command names to STDOUT
.SILENT: secretkey

# This target does not generate a file
.PHONY: secretkey

# Use the current virtual environment Python shell
secretkey: SHELL = $(PYTHON)
secretkey:
	from django.core.management.utils import get_random_secret_key
	print(get_random_secret_key())


# Catch-all target for manage.py script
# =====================================

# Default rule to call 'manage.py' script
.DEFAULT:
	@$(PYTHON) manage.py "$@"


# Final thoughts
# ==============

# - make is very powerful and has a steep learning curve, so it is advised
#   to read its manual: https://www.gnu.org/software/make/manual.
# - Or not, just use tox, nox or pyinvoke.

slides.pdf