Building Ray from Source¶
For a majority of Ray users, installing Ray via the latest wheels or pip package is usually enough. However, you may want to build the latest master branch.
If you are only editing Python files, follow instructions for Building Ray (Python Only) to avoid long build times.
To build Ray locally you will need to have the Git repository, so first, fork it on GitHub. Then you can clone it to your machine:
To clone the repository using Git with SSH (the default) run:
git clone email@example.com:[your username]/ray.git
To clone the repository using Git with HTTPS run:
git clone https://github.com/[your username]/ray.git
Then you can enter into the Ray git repository directory:
Next make sure you connect your repository to the upstream (main project) Ray repository. This will allow you to push your code to your repository when proposing changes (in pull requests) while also pulling updates from the main project.
To connect your repository using SSH (the default) run the command:
git remote add upstream firstname.lastname@example.org:ray-project/ray.git
To connect your repository using HTTPS run the command:
git remote add upstream https://github.com/ray-project/ray.git
Every time you want to update your local version you can pull the changes from the main repository:
# Checkout the local master branch git checkout master # Pull the latest changes from the main repository git pull upstream master
To setup an isolated Anaconda environment, see Installing Ray with Anaconda.
You will probably want to have some type of Python virtual environment. For example you could use Python’s integrated
venv module to create one:
python -m venv env
That will create a virtual environment called
env in the current directory, it will contain a directory with all the packages used by the local Python of your project. You only need to do this step once.
Next, you need to activate the environment to tell your shell/terminal to use this particular Python. This will also depend on the system you use to set up your virtual environment (conda, venv, or other methods).
If you are using the example from above using
venv, you would activate your virtual environment with:
You will need to activate the virtual environment every time you start a new shell/terminal to work on Ray.
After that, it’s always good to make sure you have the latest version of
wheel. When you create a new virtual environment it can come with an older version, and many strange-looking problems while installing packages are simply solved by upgrading pip to the latest version:
python -m pip install --upgrade pip wheel
That command tells Python to use the module
pip to install the latest version of
pip (itself) and
Unless otherwise stated, directory and file paths are relative to the project root directory.
RLlib, Tune, Autoscaler, and most Python files do not require you to build and compile Ray. Follow these instructions to develop Ray’s Python files locally without building Ray.
Make sure you have a clone of Ray’s git repository as explained above.
Make sure you activate the Python (virtual) environment as described above.
Pip install the latest Ray wheels. See Daily Releases (Nightlies) for instructions.
# For example, for Python 3.8: pip install -U https://s3-us-west-2.amazonaws.com/ray-wheels/latest/ray-3.0.0.dev0-cp38-cp38-manylinux2014_x86_64.whl
Replace Python files in the installed package with your local editable copy. We provide a simple script to help you do this:
python python/ray/setup-dev.py. Running the script will remove the
ray/autoscalerdir (among other directories) bundled with the
raypip package, and replace them with links to your local code. This way, changing files in your git clone will directly affect the behavior of your installed Ray.
# This replaces `<package path>/site-packages/ray/<package>` # with your local `ray/python/ray/<package>`. python python/ray/setup-dev.py
Do not run
pip uninstall ray or
pip install -U (for Ray or Ray wheels) if setting up your environment this way. To uninstall or upgrade, you must first
rm -rf the pip-installation site (usually a directory at the
site-packages/ray location), then do a pip reinstall (see the command above), and finally run the above
setup-dev.py script again.
# To uninstall, delete the symlinks first. rm -rf <package path>/site-packages/ray # Path will be in the output of `setup-dev.py`. pip uninstall ray # or `pip install -U <wheel>`
If you are only editing Tune/RLlib/Autoscaler files, follow instructions for Building Ray (Python Only) to avoid long build times.
To build Ray on Ubuntu, run the following commands:
sudo apt-get update sudo apt-get install -y build-essential curl unzip psmisc # Install Bazel. ci/env/install-bazel.sh
For RHELv8 (Redhat EL 8.0-64 Minimal), run the following commands:
sudo yum groupinstall 'Development Tools' sudo yum install psmisc
In RedHat, install Bazel manually from this link: https://docs.bazel.build/versions/main/install-redhat.html
Assuming you already have Brew and Bazel installed on your mac and you also have grpc and protobuf installed on your mac consider removing those (grpc and protobuf) for smooth build through the commands
brew uninstall grpc,
brew uninstall protobuf. If you have built the source code earlier and it still fails with errors like
No such file or directory:, try cleaning previous builds on your host by running the commands
brew uninstall binutils and
bazel clean --expunge.
To build Ray on MacOS, first install these dependencies:
brew update brew install wget # Install Bazel. ray/ci/env/install-bazel.sh
Make sure you have a local clone of Ray’s git repository as explained above. You will also need to install NodeJS to build the dashboard.
Enter into the project directory, for example:
Now you can build the dashboard. From inside of your local Ray project directory enter into the dashboard client directory:
Then you can install the dependencies and build the dashboard:
npm install npm run build
After that, you can now move back to the top level Ray directory:
Now let’s build Ray for Python. Make sure you activate any Python virtual (or conda) environment you could be using as described above.
Enter into the
python/ directory inside of the Ray project directory and install the project with
# Install Ray. cd python/ pip install -e . --verbose # Add --user if you see a permission denied error.
-e means “editable”, so changes you make to files in the Ray
directory will take effect without reinstalling the package.
if you run
python setup.py install, files will be copied from the Ray directory to a directory of Python packages (
/lib/python3.6/site-packages/ray). This means that changes you make to files in the Ray directory will not have any effect.
If your machine is running out of memory during the build or the build is causing other programs to crash, try adding the following line to
build --local_ram_resources=HOST_RAM*.5 --local_cpu_resources=4
build --disk_cache=~/bazel-cache option can be useful to speed up repeated builds too.
The following links were correct during the writing of this section. In case the URLs changed, search at the organizations’ sites.
Microsoft Visual Studio 2019 (or Microsoft Build Tools 2019 - https://visualstudio.microsoft.com/downloads/#build-tools-for-visual-studio-2019)
Miniconda 3 (https://docs.conda.io/en/latest/miniconda.html)
git for Windows, version 2.31.1 or later (https://git-scm.com/download/win)
You can also use the included script to install Bazel:
# Install Bazel. ray/ci/env/install-bazel.sh # (Windows users: please manually place Bazel in your PATH, and point # BAZEL_SH to MSYS2's Bash: ``set BAZEL_SH=C:\Program Files\Git\bin\bash.exe``)
Enable Developer mode on Windows 10 systems. This is necessary so git can create symlinks.
Open Settings app;
Go to “Update & Security”;
Go to “For Developers” on the left pane;
Turn on “Developer mode”.
Add the following Miniconda subdirectories to PATH. If Miniconda was installed for all users, the following paths are correct. If Miniconda is installed for a single user, adjust the paths accordingly.
Define an environment variable
BAZEL_SHto point to
bash.exe. If git for Windows was installed for all users, bash’s path should be
C:\Program Files\Git\bin\bash.exe. If git was installed for a single user, adjust the path accordingly.
4. Bazel 4.2 installation. Go to Bazel 4.2 release web page and download
bazel-4.2.1-windows-x86_64.exe. Copy the exe into the directory of your choice.
Define an environment variable BAZEL_PATH to full exe path (example:
set BAZEL_PATH=C:\bazel\bazel.exe). Also add the Bazel directory to the
Download ray source code and build it.
# cd to the directory under which the ray source tree will be downloaded. git clone -c core.symlinks=true https://github.com/ray-project/ray.git cd ray\python pip install -e . --verbose
You can tweak the build with the following environment variables (when running
pip install -e . or
python setup.py install):
BUILD_JAVA: If set and equal to
1, extra build steps will be executed to build java portions of the codebase
RAY_INSTALL_CPP: If set and equal to
ray-cppwill be installed
RAY_DISABLE_EXTRA_CPP: If set and equal to
1, a regular (non -
cpp) build will not provide some
SKIP_BAZEL_BUILD: If set and equal to
1, no Bazel build steps will be executed
SKIP_THIRDPARTY_INSTALL: If set will skip installation of third-party python packages
RAY_DEBUG_BUILD: Can be set to
tsan. Any other value will be ignored
BAZEL_LIMIT_CPUS: If set, it must be an integers. This will be fed to the
--local_cpu_resourcesargument for the call to Bazel, which will limit the number of CPUs used during Bazel steps.
IS_AUTOMATED_BUILD: Used in CI to tweak the build for the CI machines
SRC_DIR: Can be set to the root of the source checkout, defaults to
BAZEL_SH: used on Windows to find a
bash.exe, see below
BAZEL_PATH: used on Windows to find
bazel.exe, see below
MINGW_DIR: used on Windows to find
bazel.exeif not found in
Dependencies for the linter (
scripts/format.sh) can be installed with:
pip install -r python/requirements_linters.txt
Dependencies for running Ray unit tests under
python/ray/tests can be installed with:
pip install -r python/requirements.txt
Requirement files for running Ray Data / ML library tests are under
Currently, Ray is built with optimizations, which can take a long time and
interfere with debugging. To perform fast, debug, or optimized builds, you can
run the following (via
bazel build -c fastbuild //:ray_pkg
This will rebuild Ray with the appropriate options (which may take a while).
If you need to build all targets, you can use
"//:*" instead of
To make this change permanent, you can add an option such as the following
line to your user-level
~/.bazelrc file (not to be confused with the
If you do so, remember to revert this change, unless you want it to affect all of your development in the future.
dbg instead of
fastbuild generates more debug information,
which can make it easier to debug with a debugger like
To learn more about building the docs refer to Contributing to the Ray Documentation.
If you’d like to build Ray with custom dependencies (for example, with a
different version of Cython), you can modify your
.bzl file as follows:
http_archive( name = "cython", ..., ) if False else native.new_local_repository( name = "cython", build_file = "bazel/BUILD.cython", path = "../cython", )
This replaces the existing
http_archive rule with one that references a
sibling of your Ray directory (named
cython) using the build file
provided in the Ray repository (
If the dependency already has a Bazel build file in it, you can use
native.local_repository instead, and omit
To test switching back to the original rule, change