# Environment Setup

In order to work on Alexandria, you will need to set up your local environment. In this page, you will install and configure pyenv, Python, and Poetry, the three tools you need to work on Alexandria on your computer.

• A computer running MacOS, Ubuntu, or Windows with WSL2 (Ubuntu)
• Docker as configured by following steps one and two from this tutorial for Ubuntu 22.04 or by following this tutorial for MacOS
• If you're on MacOS, you will need homebrew to install some of the dependencies

Can't use Docker?

Most computers already have Python installed, but we want to make sure that we're using the proper version and modifying the version that comes with your computer can cause serious unexpected problems. To get around that, we recommend using pyenv, a version manager for Python.

In your terminal application, start by installing some prerequisite packages which will allow the next steps to run.

sudo apt update; sudo apt install git make build-essential libssl-dev zlib1g-dev \
libbz2-dev libreadline-dev libsqlite3-dev wget curl llvm \
libncursesw5-dev xz-utils tk-dev libxml2-dev libxmlsec1-dev libffi-dev liblzma-dev

xcode-select --install  # installs the command line tools for Mac
brew install openssl readline sqlite3 xz zlib

Now you'll install pyenv and ensure that it's working.

curl https://pyenv.run | bash

Now that it's installed, restart your terminal shell (the command line interface) so that it picks up the changes:

exec $SHELL

Check to make sure that your shell has pyenv installed and active:

pyenv --version

You should see something like this, although the version number will likely be different:

❯ pyenv --version
pyenv 2.2.4-1-6-g44db3b03

Now that pyenv is installed, we can safely install any version of Python we want without worry and can also easily change versions later if we need to.

List all the versions of Python available by running the following in your terminal -- be warned that there will be a lot of results!

pyenv install --list

Scroll up in the list until you find lines that are just numbers -- they'll look like this:

  ...
  3.9.12
  3.10.0
  3.10-dev
  3.10.1
  3.10.2
  3.10.3
  3.10.4
  3.11.0a7
  3.11-dev
  ...

Make a note of the version that is the highest number without letters or hyphens in it. At the time of this writing, the highest number is 3.10.4.

Install that version of Python with pyenv with the following command:

pyenv install 3.10.4  # replace the number here with the number you have!

This will take a little bit. Stretch your limbs and grab some water while we wait for that to run 😄

Alright! Now that it's installed, we'll set it as the default version for your computer -- don't worry, your system version of Python (if you have one) isn't going anywhere -- this will just change which version of Python is run when you just ask for "python" instead of a specific version.

First we'll check to make sure it's installed and visible:

pyenv versions

You should see something like this (again, with the version that you just installed instead of my version):

❯ pyenv versions
* system (set by /home/tester/.pyenv/version)
  3.10.4

See that asterisk next to system? That means that the version of Python that's currently installed is set as the default. We'll change that now to your version:

pyenv global 3.10.4  # replace with your version number!

Now you should be done -- check the version of Python that your shell gets by running:

python --version

It should return something like this:

❯ python --version
Python 3.10.4

Alexandria (and the other applications that surround it) uses Poetry as its dependency manager. We'll install it now.

curl -sSL https://install.python-poetry.org | python -

Because we installed the latest version of Python 3 above and set it to the global version with pyenv, Poetry will install automatically using the version we just installed.

Now we need to tell your shell how to find it. Because there many different terminal shells that you might be running, the shell that you have determines how we do the next step. To find out what shell you have, run:

basename $SHELL

It should print out the name of the shell you're using now. Mine may be different than yours, but the output should look like this:

❯ basename $SHELL
zsh

...so the shell that I'm running (and, most likely, you as well) is zsh. Once you've identified your shell, you can tell it where to find Poetry:

# zsh
echo 'export PATH=$HOME/.poetry/bin:$PATH' >> ~/.zshrc

# bash
echo 'export PATH=$HOME/.poetry/bin:$PATH' >> ~/.bashrc

If your shell is different from one of the two listed above (like fish) then you will likely know where to add the PATH addition.

Restart your shell again by running:

exec $SHELL

Verify that Poetry can be found by asking for its version:

poetry --version

Though the version number may be different, you should see something like the following:

❯ poetry --version
Poetry version 1.1.13

Congrats, you've installed pyenv, the latest version of Python, and Poetry; you're ready to set up Alexandria!