Building a Package

When you create a CLI program with Typer you probably want to create your own Python package.

That's what allows your users to install it and have it as an independent program that they can use in their terminal.

And that's also required for shell auto completion to work (unless you use your program through typer command).

Nowadays, there are several ways and tools to create Python packages (what you install with pip install something).

You might even have your favorite already.

Here's a very opinionated, short guide, showing one of the alternative ways of creating a Python package with a Typer app, from scratch.

Tip

If you already have a favorite way of creating Python packages, feel free to skip this.

Prerequisites¶

For this guide we'll use Poetry.

Poetry's docs are great, so go ahead, check them and install it.

Create a project¶

Let's say we want to create a CLI application called portal-gun.

To make sure your package doesn't collide with the package created by someone else, we'll name it with a prefix of your name.

So, if your name is Rick, we'll call it rick-portal-gun.

Create a project with Poetry:

$ poetry new rick-portal-gun

Created package rick_portal_gun in rick-portal-gun

// Enter the new project directory
cd ./rick-portal-gun

Dependencies and environment¶

Add typer[all] to your dependencies:

$ poetry add "typer[all]"

// It creates a virtual environment for your project
Creating virtualenv rick-portal-gun-w31dJa0b-py3.10 in /home/rick/.cache/pypoetry/virtualenvs
Using version ^0.1.0 for typer

Updating dependencies
Resolving dependencies... (1.2s)

Writing lock file

---> 100%

Package operations: 15 installs, 0 updates, 0 removals

  - Installing zipp (3.1.0)
  - Installing importlib-metadata (1.5.0)
  - Installing pyparsing (2.4.6)
  - Installing six (1.14.0)
  - Installing attrs (19.3.0)
  - Installing click (7.1.1)
  - Installing colorama (0.4.3)
  - Installing more-itertools (8.2.0)
  - Installing packaging (20.3)
  - Installing pluggy (0.13.1)
  - Installing py (1.8.1)
  - Installing shellingham (1.3.2)
  - Installing wcwidth (0.1.8)
  - Installing pytest (5.4.1)
  - Installing typer (0.0.11)

// Activate that new virtual environment
$ poetry shell

Spawning shell within /home/rick/.cache/pypoetry/virtualenvs/rick-portal-gun-w31dJa0b-py3.10

// Open an editor using this new environment, for example VS Code
$ code ./

You can see that you have a generated project structure that looks like:

.
├── poetry.lock
├── pyproject.toml
├── README.md
├── rick_portal_gun
│   └── __init__.py
└── tests
    ├── __init__.py
    └── test_rick_portal_gun.py

Create your app¶

Now let's create an extremely simple Typer app.

Create a file rick_portal_gun/main.py with:

import typer


app = typer.Typer()


@app.callback()
def callback():
    """
    Awesome Portal Gun
    """


@app.command()
def shoot():
    """
    Shoot the portal gun
    """
    typer.echo("Shooting portal gun")


@app.command()
def load():
    """
    Load the portal gun
    """
    typer.echo("Loading portal gun")

Tip

As we are creating an installable Python package, there's no need to add a section with if __name__ == "__main__":.

Modify the README¶

Let's change the README to have something like:

# Portal Gun

The awesome Portal Gun

Add a "script"¶

We are creating a Python package that can be installed with pip install.

But we want it to provide a CLI program that can be executed in the shell.

To do that, we add a configuration to the pyproject.toml in the section [tool.poetry.scripts]:

[tool.poetry]
name = "rick-portal-gun"
version = "0.1.0"
description = ""
authors = ["Rick Sanchez <rick@example.com>"]
readme = "README.md"

[tool.poetry.scripts]
rick-portal-gun = "rick_portal_gun.main:app"

[tool.poetry.dependencies]
python = "^3.10"
typer = {extras = ["all"], version = "^0.1.0"}

[tool.poetry.dev-dependencies]
pytest = "^5.2"

[build-system]
requires = ["poetry>=0.12"]
build-backend = "poetry.masonry.api"

Here's what that line means:

rick-portal-gun: will be the name of the CLI program. That's how we will call it in the terminal once it is installed. Like:

$ rick-portal-gun

// Something happens here ✨

rick_portal_gun.main, in the part "rick_portal_gun.main:app", with underscores, refers to the Python module to import. That's what someone would use in a section like:

from rick_portal_gun.main import # something goes here

The app in "rick_portal_gun.main:app" is the thing to import from the module, and to call as a function, like:

from rick_portal_gun.main import app
app()

That config section tells Poetry that when this package is installed we want it to create a command line program called rick-portal-gun.

And that the object to call (like a function) is the one in the variable app inside of the module rick_portal_gun.main.

Install your package¶

That's what we need to create a package.

You can now install it:

$ poetry install

Installing dependencies from lock file

No dependencies to install or update

  - Installing rick-portal-gun (0.1.0)

Try your CLI program¶

Your package is installed in the environment created by Poetry, but you can already use it.

// You can use the which program to check which rick-portal-gun program is available (if any)
$ which rick-portal-gun

// You get the one from your environment
/home/rick/.cache/pypoetry/virtualenvs/rick-portal-gun-w31dJa0b-py3.10/bin/rick-portal-gun

// Try it
$ rick-portal-gun

// You get all the standard help
Usage: rick-portal-gun [OPTIONS] COMMAND [ARGS]...

  Awesome Portal Gun

Options:
  --install-completion  Install completion for the current shell.
  --show-completion     Show completion for the current shell, to copy it or customize the installation.

  --help                Show this message and exit.

Commands:
  load   Load the portal gun
  shoot  Shoot the portal gun

Create a wheel package¶

Python packages have a standard format called a "wheel". It's a file that ends in .whl.

You can create a wheel with Poetry:

$ poetry build

Building rick-portal-gun (0.1.0)
 - Building sdist
 - Built rick-portal-gun-0.1.0.tar.gz

 - Building wheel
 - Built rick_portal_gun-0.1.0-py3-none-any.whl

After that, if you check in your project directory, you should now have a couple of extra files at ./dist/:

.
├── dist
│   ├── rick_portal_gun-0.1.0-py3-none-any.whl
│   └── rick-portal-gun-0.1.0.tar.gz
├── pyproject.toml
├── README.md
├── ...

The .whl is the wheel file. You can send that wheel file to anyone and they can use it to install your program (we'll see how to upload it to PyPI in a bit).

Test your wheel package¶

Now you can open another terminal and install that package from the file for your own user with:

$ pip install --user /home/rock/code/rick-portal-gun/dist/rick_portal_gun-0.1.0-py3-none-any.whl

---> 100%

Warning

The --user is important, that ensures you install it in your user's directory and not in the global system.

If you installed it in the global system (e.g. with sudo) you could install a version of a library (e.g. a sub-dependency) that is incompatible with your system.

Tip

Bonus points if you use pipx to install it while keeping an isolated environment for your Python CLI programs 🚀

Now you have your CLI program installed. And you can use it freely:

$ rick-portal-gun shoot

// It works 🎉
Shooting portal gun

Having it installed globally (and not in a single environment), you can now install completion globally for it:

$ rick-portal-gun --install-completion

zsh completion installed in /home/user/.zshrc.
Completion will take effect once you restart the terminal.

Tip

If you want to remove completion you can just delete the added line in that file.

And after you restart the terminal you will get completion for your new CLI program:

$ rick-portal-gun [TAB][TAB]

// You get completion for your CLI program ✨
load   -- Load the portal gun
shoot  -- Shoot the portal gun

Support `python -m` (optional)¶

You may have seen that you can call many Python modules as scripts with python -m some-module.

For example, one way to call pip is:

$ pip install fastapi

But you can also call Python with the -m CLI Option and pass a module for it to execute as if it was a script, like:

$ python -m pip install fastapi

Here we pass pip as the value for -m, so, Python will execute the module pip as if it was a script. And then it will pass the rest of the CLI Parameters (install fastapi) to it.

These two are more or less equivalent, the install fastapi will be passed to pip.

Tip

In the case of pip, in many occasions it's actually recommended that you run it with python -m, because if you create a virtual environment with its own python, that will ensure that you use the pip from that environment.

Add a `main.py`¶

You can support that same style of calling the package/module for your own package, simply by adding a file __main__.py.

Python will look for that file and execute it.

The file would live right beside __init__.py:

.
├── poetry.lock
├── pyproject.toml
├── README.md
├── rick_portal_gun
│   ├── __init__.py
│   ├── __main__.py
│   └── main.py
└── tests
    ├── __init__.py
    └── test_rick_portal_gun.py

No other file has to import it, you don't have to reference it in your pyproject.toml or anything else, it just works by default, as it is standard Python behavior.

Then in that file you can execute your Typer program:

from .main import app
app()

Now, after installing your package, if you call it with python -m it will work (for the main part):

$ python -m rick_portal_gun

Usage: __main__.py [OPTIONS] COMMAND [ARGS]...

  Awesome Portal Gun

Options:
  --install-completion  Install completion for the current shell.
  --show-completion     Show completion for the current shell, to copy it or customize the installation.

  --help                Show this message and exit.

Commands:
  load   Load the portal gun
  shoot  Shoot the portal gun

Tip

Notice that you have to pass the importable version of the package name, so rick_portal_gun instead of rick-portal-gun.

That works! 🚀 Sort of... 🤔

See the __main__.py in the help instead of rick-portal-gun? We'll fix that next.

Set a program name in `main.py`¶

We are setting the program name in the file pyproject.toml in the line like:

[tool.poetry.scripts]
rick-portal-gun = "rick_portal_gun.main:app"

But when Python runs our package as a script with python -m, it doesn't have the information of the program name.

So, to fix the help text to use the correct program name when called with python -m, we can pass it to the app in __main__.py:

from .main import app
app(prog_name="rick-portal-gun")

Tip

You can pass all the arguments and keyword arguments you could pass to a Click application, including prog_name.

$ python -m rick_portal_gun

Usage: rick-portal-gun [OPTIONS] COMMAND [ARGS]...

  Awesome Portal Gun

Options:
  --install-completion  Install completion for the current shell.
  --show-completion     Show completion for the current shell, to copy it or customize the installation.

  --help                Show this message and exit.

Commands:
  load   Load the portal gun
  shoot  Shoot the portal gun

Great! That works correctly! 🎉 ✅

Notice that now it uses rick-portal-gun instead of __main__.py in the help.

Autocompletion and `python -m`¶

Have in mind that TAB completion (shell auto-completion) won't work when using python -m.

Auto-completion depends on the name of the program called, it's tied to each specific program name.

So, to have shell completion for rick-portal-gun you would have to call it directly:

$ rick-portal-gun [TAB][TAB]

But you can still support python -m for the cases where it's useful.

Publish to PyPI (optional)¶

You can publish that new package to PyPI to make it public, so others can install it easily.

So, go ahead and create an account there (it's free).

PyPI API token¶

To do it, you first need to configure a PyPI auth token.

Login to PyPI.

And then go to https://pypi.org/manage/account/token/ to create a new token.

Let's say your new API token is:

pypi-wubalubadubdub-deadbeef1234

Now configure Poetry to use this token with the command poetry config pypi-token.pypi:

$ poetry config pypi-token.pypi pypi-wubalubadubdub-deadbeef1234
// It won't show any output, but it's already configured

Publish to PyPI¶

Now you can publish your package with Poetry.

You could build the package (as we did above) and then publish later, or you could tell poetry to build it before publishing in one go:

$ poetry publish --build

# There are 2 files ready for publishing. Build anyway? (yes/no) [no] $ yes

---> 100%

Building rick-portal-gun (0.1.0)
 - Building sdist
 - Built rick-portal-gun-0.1.0.tar.gz

 - Building wheel
 - Built rick_portal_gun-0.1.0-py3-none-any.whl

Publishing rick-portal-gun (0.1.0) to PyPI
 - Uploading rick-portal-gun-0.1.0.tar.gz 100%
 - Uploading rick_portal_gun-0.1.0-py3-none-any.whl 100%

Now you can go to PyPI and check your projects at https://pypi.org/manage/projects/.

You should now see your new "rick-portal-gun" package.

Install from PyPI¶

Now to see that we can install it form PyPI, open another terminal, and uninstall the currently installed package.

$ pip uninstall rick-portal-gun

Found existing installation: rick-portal-gun 0.1.0
Uninstalling rick-portal-gun-0.1.0:
  Would remove:
    /home/user/.local/bin/rick-portal-gun
    /home/user/.local/lib/python3.10/site-packages/rick_portal_gun-0.1.0.dist-info/*
    /home/user/.local/lib/python3.10/site-packages/rick_portal_gun/*
# Proceed (y/n)? $ y
    Successfully uninstalled rick-portal-gun-0.1.0

And now install it again, but this time using just the name, so that pip pulls it from PyPI:

$ pip install --user rick-portal-gun

// Notice that it says "Downloading" 🚀
Collecting rick-portal-gun
  Downloading rick_portal_gun-0.1.0-py3-none-any.whl (1.8 kB)
Requirement already satisfied: typer[all]<0.0.12,>=0.0.11 in ./.local/lib/python3.10/site-packages (from rick-portal-gun) (0.0.11)
Requirement already satisfied: click<7.2.0,>=7.1.1 in ./anaconda3/lib/python3.10/site-packages (from typer[all]<0.0.12,>=0.0.11->rick-portal-gun) (7.1.1)
Requirement already satisfied: colorama; extra == "all" in ./anaconda3/lib/python3.10/site-packages (from typer[all]<0.0.12,>=0.0.11->rick-portal-gun) (0.4.3)
Requirement already satisfied: shellingham; extra == "all" in ./anaconda3/lib/python3.10/site-packages (from typer[all]<0.0.12,>=0.0.11->rick-portal-gun) (1.3.1)
Installing collected packages: rick-portal-gun
Successfully installed rick-portal-gun-0.1.0

And now test the newly installed package from PyPI:

$ rick-portal-gun load

// It works! 🎉
Loading portal gun

Generate docs¶

You can use the typer command to generate docs for your package that you can put in your README.md:

$ typer rick_portal_gun.main utils docs --output README.md --name rick-portal-gun

Docs saved to: README.md

You just have to pass it the module to import (rick_portal_gun.main) and it will detect the typer.Typer app automatically.

By specifying the --name of the program it will be able to use it while generating the docs.

Tip

If you installed typer-slim and don't have the typer command, you can use python -m typer instead.

Publish a new version with the docs¶

Now you can publish a new version with the updated docs.

For that you need to first increase the version in pyproject.toml:

[tool.poetry]
name = "rick-portal-gun"
version = "0.2.0"
description = ""
authors = ["Rick Sanchez <rick@example.com>"]
readme = "README.md"

[tool.poetry.scripts]
rick-portal-gun = "rick_portal_gun.main:app"

[tool.poetry.dependencies]
python = "^3.10"
typer = {extras = ["all"], version = "^0.1.0"}

[tool.poetry.dev-dependencies]
pytest = "^5.2"

[build-system]
requires = ["poetry>=0.12"]
build-backend = "poetry.masonry.api"

And in the file rick_portal_gun/__init__.py:

__version__ = '0.2.0'

And then build and publish again:

$ poetry publish --build

---> 100%

Building rick-portal-gun (0.2.0)
 - Building sdist
 - Built rick-portal-gun-0.2.0.tar.gz

 - Building wheel
 - Built rick_portal_gun-0.2.0-py3-none-any.whl

Publishing rick-portal-gun (0.2.0) to PyPI
 - Uploading rick-portal-gun-0.2.0.tar.gz 100%
 - Uploading rick_portal_gun-0.2.0-py3-none-any.whl 100%

And now you can go to PyPI, to the project page, and reload it, and it will now have your new generated docs.

What's next¶

This is a very simple guide. You could add many more steps.

For example, you should use Git, the version control system, to save your code.

You can add a lot of extra metadata to your pyproject.toml, check the docs for Poetry: Libraries.

You could use pipx to manage your installed CLI Python programs in isolated environments.

Maybe use automatic formatting with Black.

You'll probably want to publish your code as open source to GitHub.

And then you could integrate a CI tool to run your tests and deploy your package automatically.

And there's a long etc. But now you have the basics and you can continue on your own 🚀.