Building Ray on Windows

Requirements

The following links were correct during the writing of this section. In case the URLs changed, search at the organizations' sites.

• bazel 4.2 (https://github.com/bazelbuild/bazel/releases/tag/4.2.1)
• Microsoft Visual Studio 2019 (or Microsoft Build Tools 2019 - https://visualstudio.microsoft.com/downloads/#build-tools-for-visual-studio-2019)
• JDK 15 (https://www.oracle.com/java/technologies/javase-jdk15-downloads.html)
• 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)

Steps

1. Enable Developer mode on Windows 10 systems. This is necessary so git can create symlinks.
   1. Open Settings app;
   2. Go to "Update & Security";
   3. Go to "For Developers" on the left pane;
   4. Turn on "Developer mode".
2. 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.
   • C:\ProgramData\Miniconda3
   • C:\ProgramData\Miniconda3\Scripts
   • C:\ProgramData\Miniconda3\Library\bin

3. Define an environment variable BAZEL_SH to 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 PATH (example: set PATH=%PATH%;C:\bazel)

5. Install cython and pytest:

pip install cython==0.29.0 pytest

1. 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