Development Setup

This page will walk you through what you need to do if you want to be able to contribute code or documentation to the PUDL project.

These instructions assume that you are working on a Unix-like operating system (MacOS or Linux) and are already familiar with git, GitHub, and the Unix shell.


While it should be possible to set up the development environment on Windows, we haven’t done it. In the future we may create a Docker image that provides the development environment. E.g. for use with VS Code’s Containers extension.


If you’re new to git and GitHub , you’ll want to check out:

Install conda / mamba

We use the mamba package manager to specify and update our development environment, preferentially installing packages from the community maintained conda-forge distribution channel. We recommend using miniforge to install mamba and automatically default to the conda-forge channel.

After installing your package manager, make sure it’s configured to use strict channel priority with the following commands:

$ mamba update mamba
$ conda config --set channel_priority strict


Make sure that after you’ve installed conda or mamba that you can activate and deactivate the base environment (which is created by default). Try creating a simple new environment and activating it to make sure everything is working and your shell has been correctly configured to use the new package manager.

Fork and Clone the PUDL Repository

Unless you’re part of the Catalyst Cooperative organization already, you’ll need to fork the PUDL repository This makes a copy of it in your personal (or organizational) account on GitHub that is independent of, but linked to, the original “upstream” project.

Then, clone the repository from your fork to your local computer where you’ll be editing the code or docs. This will download the whole history of the project, including the most recent version, and put it in a local directory where you can make changes.

Note that we use a special merge method for our environment lockfiles, which you need to explicitly enable locally in your git configuration for the PUDL repository with this command. You only need to run it once, from within the cloned repo:

$ git config --local merge.ours.driver true


If there have been changes to the environment on a branch (e.g. dev) that you merge into your own branch, the lockfiles will need to be regenerated. This can be done automatically by pushing the merged changes to your branch on GitHub, waiting a couple of minutes for the update-conda-lockfile GitHub Action to run, and then pulling the fresh lockfiles to your local development environment. You can also regenerate the lockfiles locally (see below).

Create the PUDL Dev Environment

We use conda-lock to specify particular versions of all of PUDL’s direct and indirect software dependencies in a lockfile, resulting in a stable, reproducible environment. This lockfile and several platform-specific rendered environment files are stored under the environments/ directory in the main PUDL repository.

All of the dependencies in environments/conda-lock.yml are derived from packages listed in the project’s pyproject.toml file. The conda lockfile is updated automatically by a GitHub Action workflow that runs once a week, or any time pyproject.toml is changed.

We use a Makefile to remember and automate some common shared tasks in the PUDL repository, including creating and updating the pudl-dev conda environment. If you are on a Unix-based platform (Linux or MacOS) the make command should already be installed. You’ll typically want to use the predefined make commands rather than running the individual commands they wrap. If you’d like to learn more about how Makefiles work, check out this excellent Makefile tutorial

To create the pudl-dev environment, install the local PUDL package, and activate the newly created environment, run:

$ make install-pudl
$ mamba activate pudl-dev

If you want to see all the bundled commands we’ve defined, open up the Makefile. There’s also some additional information in the Testing PUDL documentation.

Updating the PUDL Development Environment

You will need to periodically update your installed development (pudl-dev) conda environment to get you newer versions of existing dependencies and incorporate any changes to the environment specification that have been made by other contributors. The most reliable way to do this is to remove the existing environment and recreate it.

Recreating the pudl-dev environment from scratch uses the same make command as creating it the first time:

$ make install-pudl

If you happen to be changing the dependencies listed in pyproject.toml and you want to re-create the conda lockfile from scratch to include any newly defined dependencies, and then create a fresh pudl-dev environment using the new lockfile, you can do:

$ make conda-clean
$ make conda-lock.yml
$ make install-pudl

However, unless you are adding or removing dependencies from pyproject.toml it is probably best to just use the already prepared lockfile, and allow it to be updated automatically by the weekly GitHub Action.


Different development branches within the repository may specify their own slightly different versions of the pudl-dev conda environment. As a result, you may need to update your environment when switching from one branch to another to ensure that the codebase and the dependencies are in sync.

If you want to work with the most recent version of the code on a branch named new-feature, then from within the top directory of the PUDL repository you would do:

$ git checkout new-feature
$ git pull
$ make install-pudl
$ mamba activate pudl-dev

If you are working with locally processed data and there have been changes to the expectations about that data in the PUDL software, you may also need to regenerate your PUDL SQLite database or other outputs. See Running the ETL Pipeline for more details.

Set Up Code Linting

We use several automated tools to apply uniform coding style and formatting across the project codebase. This is known as code linting, and it reduces merge conflicts, makes the code easier to read, and helps catch some types of bugs before they are committed. These tools are part of the pudl-dev conda environment and their configuration files are checked into the GitHub repository. If you’ve cloned the pudl repo and are working inside the pudl conda environment, they should be installed and ready to go.

Git Pre-commit Hooks

Git hooks let you automatically run scripts at various points as you manage your source code. “Pre-commit” hook scripts are run when you try to make a new commit. These scripts can review your code and identify bugs, formatting errors, bad coding habits, and other issues before the code gets checked in. This gives you the opportunity to fix those issues before publishing them.

To make sure they are run before you commit any code, you need to enable the pre-commit hooks scripts with this command:

$ pre-commit install

The scripts that run are configured in the .pre-commit-config.yaml file.

See also

Linting and Formatting

  • ruff is a popular, fast Python linting and autofix framework, with a large selection of rules that can be configured (often mirroring plugins originally developed for flake8). We use it to check the formatting and syntax of the code and to ensure that we’re all using modern python syntax, type hinting, etc.

  • We also use ruff to format our code. It serves as a much faster drop-in replacement for longtime crowd favorite black

  • doc8 , lints our documentation files, which are written in the reStructuredText format and built by Sphinx. This is the de-facto standard for Python documentation. The doc8 tool checks for syntax errors and other formatting issues in the documentation source files under the docs/ directory.

Linting Within Your Editor

If you are using an editor designed for Python development many of these code linting and formatting tools can be run automatically in the background while you write code or documentation. Popular editors that work with the above tools include:

Each of these editors have their own collection of plugins and settings for working with linters, formatters, and other code analysis tools.

Creating a Workspace

PUDL Workspace Setup

PUDL needs to know where to store its big piles of inputs and outputs. The PUDL_OUTPUT and PUDL_INPUT environment variables let PUDL know where all this stuff should go. We call this a “PUDL workspace”.

First, create a directory to store local caches of raw PUDL data. You can put this anywhere, but we put this in ~/pudl_input in the documentation. Then create an environment variable called PUDL_INPUT to store the path to this new directory and make sure that it is set whenever you start up a new shell. These shorthand commands will append a line to the end of your shell initialization file. If you need to change it later you’ll want to edit those files directly. Note that in the commands below you must replace the example path /absolute/path/to/pudl_input with the actual path to the directory you’ve created.

$ echo "export PUDL_INPUT=/absolute/path/to/pudl_input" >> ~/.zshrc # if you are using zsh
$ echo "export PUDL_INPUT=/absolute/path/to/pudl_input" >> ~/.bashrc # if you are using bash
$ set -Ux PUDL_INPUT /absolute/path/to/pudl_input # if you are using fish shell

The directory stored in PUDL_INPUT contains versions of PUDL’s raw data archives on Zenodo for each datasource:

├── ferc1/
│   ├── 10.5281-zenodo.5534788/
│   │   ├── datapackage.json
│   │   ├──
│   │   ├──
│   │   └── ...
│   ├── 10.5281-zenodo.7314437/
│   │   └── ...
│   └── ...
├── eia860/
│   └── ...
└── ...


The data stored at the PUDL_INPUT directory can grow to be dozens of gigabytes in size. This is because when the raw data are updated, a new version of the archive is downloaded to the PUDL_INPUT directory. To slim down the size you can always delete out of date archives the code no longer depends on.

Next, create a directory to store the outputs of the PUDL ETL. As above, you can put this anywhere, but typically this is ~/pudl_output. Then, as with PUDL_INPUT, create an environment variable called PUDL_OUTPUT to store the path to this new directory. In the commands below you must replace the example path /absolute/path/to/pudl_output with the actual path to the directory you want to use.

$ echo "export PUDL_OUTPUT=/absolute/path/to/pudl_output" >> ~/.zshrc # zsh
$ echo "export PUDL_OUTPUT=/absolute/path/to/pudl_output" >> ~/.bashrc # bash
$ set -Ux PUDL_OUTPUT /absolute/path/to/pudl_output # fish

The path stored in PUDL_OUTPUT contains all ETL outputs like pudl.sqlite and core_epacems__hourly_emissions.parquet.


Make sure you set these environment variables to point at separate directories! It is also strongly recommended that you create these directories outside of the pudl repository directory so the inputs and outputs are not tracked in git.

Remember that you’ll need to either source your shell profile after adding the new environment variable definitions above, or export them at the command line for them to be active in the current shell. Again, note that these are fake example paths:

$ export PUDL_OUTPUT=/absolute/path/to/pudl_output
$ export PUDL_INPUT=/absolute/path/to/pudl_input