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Makefiles

Goku Mohandas
· ·
An automation tool that organizes commands for our application's processes.
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Intuition

We have just started and there are already so many different commands to keep track of. To help with this, we're going to use a Makefile which is a automation tool that organizes our commands. This makes it very easy for us to organize relevant commands as well as organize it for others who may be new to our application.

Application

Components

Inside our Makefile, we can see a list of rules (help, install, etc.). These rules have a target which can sometimes have prerequisites that need to be met (can be other targets) and on the next line a Tab followed by a recipe which specifies how to create the target.

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# Makefile
target: prerequisites
<TAB> recipe

Targets

We can execute any of the rules by typing make <target>:

# View all rules
$ make help
Usage: tagifai [OPTIONS] COMMAND [ARGS]
👉  Commands:
    install         : installs required packages.
    install-dev     : installs development requirements.
    install-test    : installs test requirements.
    ...

# Make a target
$ make install-dev
python -m pip install -e ".[dev]"
...

Note

Each line in a recipe for a rule will execute in a separate sub-shell. However for certain recipes such as activating a virtual environment and loading packages, we want to do it all in one shell. To do this, we can add the .ONESHELL special target above any target like so: 

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.ONESHELL:
venv:
    python3 -m venv ${name}
    source ${name}/bin/activate
    python -m pip install --upgrade pip setuptools wheel
    make install-dev
However this is only available in Make version 3.82 and above and most Macs currently user version 3.81. You can either update to the current version or chain your commands with && like so: 
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venv:
    python3 -m venv ${name}
    source ${name}/bin/activate && \
    python -m pip install --upgrade pip setuptools wheel && \
    make install-dev

PHONY

A Makefile is called as such because traditionally the targets are supposed to be files we can make. However, Makefiles are also commonly used as command shortcuts which can lead to confusion when a file with a certain name exists and a Makefile rule with the same name exists! For example if you a directory called docs and a target in your Makefile called docs, when you run make docs you'll get this message:

$ make docs
make: `docs` is up to date.

We can fix this by defining a PHONY target in our makefile by adding this line above the target: 

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.PHONY: <target_name>

Most of the rules in our Makefile will require the PHONY target because we want them to execute even if there is a file sharing the target's name. An exception to this is the venv target because we don't want to create a venv directory if it already exists.

Variables

We can also set and use variables inside our Makefile to organize all of our rules.

  • We can set the variables directly inside the Makefile. If the variable isn't defined in the Makefile, then it would default to any environment variable with the same name. 

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    # Set variable
MESSAGE := "hello world"

# Use variable
greeting:
    @echo ${MESSAGE}

  • We can also use variables passed in when executing the rule like so (ensure that the variable is not overriden inside the Makefile): 

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    make greeting MESSAGE="hi"

There's a whole lot more to Makefiles but this is plenty for most applied ML projects.

To cite this lesson, please use:

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@article{madewithml,
    title  = "Makefile - Made With ML",
    author = "Goku Mohandas",
    url    = "https://madewithml.com/courses/mlops/makefile/"
    year   = "2021",
}