# Contributing

We have issues labeled as
[Good First Issue](https://github.com/astral-sh/uv/issues?q=is%3Aopen+is%3Aissue+label%3A%22good+first+issue%22)
and
[Help Wanted](https://github.com/astral-sh/uv/issues?q=is%3Aopen+is%3Aissue+label%3A%22help+wanted%22)
which are good opportunities for new contributors.

## Setup

[Rust](https://rustup.rs/) (and a C compiler) are required to build uv.

On Ubuntu and other Debian-based distributions, you can install a C compiler with:

```shell
sudo apt install build-essential
```

## Testing

For running tests, we recommend [nextest](https://nexte.st/).

If tests fail due to a mismatch in the JSON Schema, run: `cargo dev generate-json-schema`.

### Python

Testing uv requires multiple specific Python versions; they can be installed with:

```shell
cargo run python install
```

The storage directory can be configured with `UV_PYTHON_INSTALL_DIR`. (It must be an absolute path.)

### Snapshot testing

uv uses [insta](https://insta.rs/) for snapshot testing. It's recommended (but not necessary) to use
`cargo-insta` for a better snapshot review experience. See the
[installation guide](https://insta.rs/docs/cli/) for more information.

In tests, you can use `uv_snapshot!` macro to simplify creating snapshots for uv commands. For
example:

```rust
#[test]
fn test_add() {
    let context = TestContext::new("3.12");
    uv_snapshot!(context.filters(), context.add().arg("requests"), @"");
}
```

To run and review a specific snapshot test:

```shell
cargo test --package <package> --test <test> -- <test_name> -- --exact
cargo insta review
```

### Local testing

You can invoke your development version of uv with `cargo run -- <args>`. For example:

```shell
cargo run -- venv
cargo run -- pip install requests
```

## Running inside a Docker container

Source distributions can run arbitrary code on build and can make unwanted modifications to your
system
(["Someone's Been Messing With My Subnormals!" on Blogspot](https://moyix.blogspot.com/2022/09/someones-been-messing-with-my-subnormals.html),
["nvidia-pyindex" on PyPI](https://pypi.org/project/nvidia-pyindex/)), which can even occur when
just resolving requirements. To prevent this, there's a Docker container you can run commands in:

```console
$ docker build -t uv-builder -f crates/uv-dev/builder.dockerfile --load .
# Build for musl to avoid glibc errors, might not be required with your OS version
cargo build --target x86_64-unknown-linux-musl --profile profiling
docker run --rm -it -v $(pwd):/app uv-builder /app/target/x86_64-unknown-linux-musl/profiling/uv-dev resolve-many --cache-dir /app/cache-docker /app/scripts/popular_packages/pypi_10k_most_dependents.txt
```

We recommend using this container if you don't trust the dependency tree of the package(s) you are
trying to resolve or install.

## Profiling and Benchmarking

Please refer to Ruff's
[Profiling Guide](https://github.com/astral-sh/ruff/blob/main/CONTRIBUTING.md#profiling-projects),
it applies to uv, too.

We provide diverse sets of requirements for testing and benchmarking the resolver in
`scripts/requirements` and for the installer in `scripts/requirements/compiled`.

You can use `scripts/benchmark` to benchmark predefined workloads between uv versions and with other
tools, e.g., from the `scripts/benchmark` directory:

```shell
uv run resolver \
    --uv-pip \
    --poetry \
    --benchmark \
    resolve-cold \
    ../scripts/requirements/trio.in
```

### Analyzing concurrency

You can use [tracing-durations-export](https://github.com/konstin/tracing-durations-export) to
visualize parallel requests and find any spots where uv is CPU-bound. Example usage, with `uv` and
`uv-dev` respectively:

```shell
RUST_LOG=uv=info TRACING_DURATIONS_FILE=target/traces/jupyter.ndjson cargo run --features tracing-durations-export --profile profiling -- pip compile scripts/requirements/jupyter.in
```

```shell
RUST_LOG=uv=info TRACING_DURATIONS_FILE=target/traces/jupyter.ndjson cargo run --features tracing-durations-export --bin uv-dev --profile profiling -- resolve jupyter
```

### Trace-level logging

You can enable `trace` level logging using the `RUST_LOG` environment variable, i.e.

```shell
RUST_LOG=trace uv
```

## Documentation

To preview any changes to the documentation locally:

1. Install the [Rust toolchain](https://www.rust-lang.org/tools/install).

2. Run `cargo dev generate-all`, to update any auto-generated documentation.

3. Run the development server with:

   ```shell
   # For contributors.
   uvx --with-requirements docs/requirements.txt -- mkdocs serve -f mkdocs.public.yml

   # For members of the Astral org, which has access to MkDocs Insiders via sponsorship.
   uvx --with-requirements docs/requirements-insiders.txt -- mkdocs serve -f mkdocs.insiders.yml
   ```

The documentation should then be available locally at
[http://127.0.0.1:8000/uv/](http://127.0.0.1:8000/uv/).

To update the documentation dependencies, edit `docs/requirements.in` and
`docs/requirements-insiders.in`, then run:

```shell
uv pip compile docs/requirements.in -o docs/requirements.txt --universal -p 3.12
uv pip compile docs/requirements-insiders.in -o docs/requirements-insiders.txt --universal -p 3.12
```

Documentation is deployed automatically on release by publishing to the
[Astral documentation](https://github.com/astral-sh/docs) repository, which itself deploys via
Cloudflare Pages.

After making changes to the documentation, format the markdown files with:

```shell
npx prettier --prose-wrap always --write "**/*.md"
```

## Releases

Releases can only be performed by Astral team members.

Changelog entries and version bumps are automated. First, run:

```shell
./scripts/release.sh
```

Then, editorialize the `CHANGELOG.md` file to ensure entries are consistently styled.

Then, open a pull request, e.g., `Bump version to ...`.

Binary builds will automatically be tested for the release.

After merging the pull request, run the
[release workflow](https://github.com/astral-sh/uv/actions/workflows/release.yml) with the version
tag. **Do not include a leading `v`**. The release will automatically be created on GitHub after
everything else publishes.