Bazel improvements (#7427)

* Make wget quiet

* Make sphinx-build quiet

* Remove -q from pip install in CI script as config already takes care of it

* Add documentation on custom dependencies

* formatting

* python

.travis.yml

@@ -98,9 +98,9 @@ matrix:
         - ./ci/travis/install-dependencies.sh
         - export PATH="$HOME/miniconda/bin:$PATH"
         - cd doc
-        - pip install -q -r requirements-doc.txt
-        - pip install -q yapf==0.23.0
-        - sphinx-build -W -b html -d _build/doctrees source _build/html
+        - pip install -r requirements-doc.txt
+        - pip install yapf==0.23.0
+        - sphinx-build -q -W -b html -d _build/doctrees source _build/html
         - cd ..
         # Run Python linting, ignore dict vs {} (C408), others are defaults
         - flake8 --inline-quotes '"' --no-avoid-escape --exclude=python/ray/core/generated/,streaming/python/generated,doc/source/conf.py,python/ray/cloudpickle/,python/ray/thirdparty_files --ignore=C408,E121,E123,E126,E226,E24,E704,W503,W504,W605
@@ -110,7 +110,7 @@ matrix:
         - python setup.py check --restructuredtext --strict --metadata
         - cd ..
         # Run Bazel linter Buildifier.
-        - wget https://dl.google.com/go/go1.11.linux-amd64.tar.gz
+        - wget -q https://dl.google.com/go/go1.11.linux-amd64.tar.gz
         - tar -xf go1.11.linux-amd64.tar.gz
         - mkdir $HOME/go_dir
         - export GOROOT=`pwd`/go

doc/source/development.rst

@@ -38,6 +38,31 @@ the following:
 This command is not enough to recompile all C++ unit tests. To do so, see
 `Testing locally`_.
 
+Using a local repository for dependencies
+-----------------------------------------
+
+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:
+
+.. code-block:: python
+
+  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 (``bazel/BUILD.cython``).
+If the dependency already has a Bazel build file in it, you can use
+``native.local_repository`` instead, and omit ``build_file``.
+
+To test switching back to the original rule, change ``False`` to ``True``.
+
 Debugging
 ---------