[core] [7/N] Add doc for runtime env setup with uv (#48637)

Signed-off-by: dentiny <[email protected]>

doc/source/ray-core/handling-dependencies.rst

@@ -405,6 +405,23 @@ The ``runtime_env`` is a Python dictionary or a Python class :class:`ray.runtime
   When specifying a path to a ``requirements.txt`` file, the file must be present on your local machine and it must be a valid absolute path or relative filepath relative to your local current working directory, *not* relative to the ``working_dir`` specified in the ``runtime_env``.
   Furthermore, referencing local files *within* a ``requirements.txt`` file isn't directly supported (e.g., ``-r ./my-laptop/more-requirements.txt``, ``./my-pkg.whl``). Instead, use the ``${RAY_RUNTIME_ENV_CREATE_WORKING_DIR}`` environment variable in the creation process. For example, use ``-r ${RAY_RUNTIME_ENV_CREATE_WORKING_DIR}/my-laptop/more-requirements.txt`` or ``${RAY_RUNTIME_ENV_CREATE_WORKING_DIR}/my-pkg.whl`` to reference local files, while ensuring they're in the ``working_dir``.
 
+- ``uv`` (dict | List[str] | str): Alpha version feature. Either (1) a list of uv `requirements specifiers <https://pip.pypa.io/en/stable/cli/pip_install/#requirement-specifiers>`_, (2) a string containing
+  the path to a local uv `“requirements.txt” <https://pip.pypa.io/en/stable/user_guide/#requirements-files>`_ file, or (3) a python dictionary that has three fields: (a) ``packages`` (required, List[str]): a list of uv packages,
+  (b) ``uv_version`` (optional, str): the version of uv; Ray will spell the package name "uv" in front of the ``uv_version`` to form the final requirement string.
+  The syntax of a requirement specifier is the same as ``pip`` requirements.
+  This will be installed in the Ray workers at runtime.  Packages in the preinstalled cluster environment will still be available.
+  To use a library like Ray Serve or Ray Tune, you will need to include ``"ray[serve]"`` or ``"ray[tune]"`` here.
+  The Ray version must match that of the cluster.
+
+  - Example: ``["requests==1.0.0", "aiohttp", "ray[serve]"]``
+
+  - Example: ``"./requirements.txt"``
+
+  - Example: ``{"packages":["tensorflow", "requests"], "uv_version": "==0.4.0;python_version=='3.8.11'"}``
+
+  When specifying a path to a ``requirements.txt`` file, the file must be present on your local machine and it must be a valid absolute path or relative filepath relative to your local current working directory, *not* relative to the ``working_dir`` specified in the ``runtime_env``.
+  Furthermore, referencing local files *within* a ``requirements.txt`` file isn't directly supported (e.g., ``-r ./my-laptop/more-requirements.txt``, ``./my-pkg.whl``). Instead, use the ``${RAY_RUNTIME_ENV_CREATE_WORKING_DIR}`` environment variable in the creation process. For example, use ``-r ${RAY_RUNTIME_ENV_CREATE_WORKING_DIR}/my-laptop/more-requirements.txt`` or ``${RAY_RUNTIME_ENV_CREATE_WORKING_DIR}/my-pkg.whl`` to reference local files, while ensuring they're in the ``working_dir``.
+
 - ``conda`` (dict | str): Either (1) a dict representing the conda environment YAML, (2) a string containing the path to a local
   `conda “environment.yml” <https://conda.io/projects/conda/en/latest/user-guide/tasks/manage-environments.html#create-env-file-manually>`_ file,
   or (3) the name of a local conda environment already installed on each node in your cluster (e.g., ``"pytorch_p36"``) or its absolute path (e.g. ``"/home/youruser/anaconda3/envs/pytorch_p36"``) .