Merge pull request #6469 from soltanmm/doctools

Add Python grpcio-tools documentation

tools/distrib/python/grpcio_tools/MANIFEST.in

 include grpc_version.py
 include protoc_deps.py
 include protoc_lib_deps.py
+include README.rst
 graft grpc
 graft grpc_root
 graft third_party

tools/distrib/python/grpcio_tools/README.rst

+gRPC Python Tools
+=================
+
+Package for gRPC Python tools.
+
+Installation
+------------
+
+The gRPC Python tools package is available for Linux, Mac OS X, and Windows
+running Python 2.7.
+
+From PyPI
+~~~~~~~~~
+
+If you are installing locally...
+
+::
+
+  $ pip install grpcio-tools
+
+Else system wide (on Ubuntu)...
+
+::
+
+  $ sudo pip install grpcio-tools
+
+If you're on Windows make sure that you installed the :code:`pip.exe` component
+when you installed Python (if not go back and install it!) then invoke:
+
+::
+
+  $ pip.exe install grpcio-tools
+
+Windows users may need to invoke :code:`pip.exe` from a command line ran as
+administrator.
+
+n.b. On Windows and on Mac OS X one *must* have a recent release of :code:`pip`
+to retrieve the proper wheel from PyPI. Be sure to upgrade to the latest
+version!
+
+You might also need to install Cython to handle installation via the source
+distribution if gRPC Python's system coverage with wheels does not happen to
+include your system.
+
+From Source
+~~~~~~~~~~~
+
+Building from source requires that you have the Python headers (usually a
+package named :code:`python-dev`) and Cython installed.
+
+::
+
+  $ export REPO_ROOT=grpc  # REPO_ROOT can be any directory of your choice
+  $ git clone https://github.com/grpc/grpc.git $REPO_ROOT
+  $ cd $REPO_ROOT
+  $ git submodule update --init
+
+  $ cd tools/distrib/python/grpcio_tools
+  $ python ../make_grpcio_tools.py
+
+  # For the next command do `sudo pip install` if you get permission-denied errors
+  $ pip install .
+
+You cannot currently install Python from source on Windows. Things might work
+out for you in MSYS2 (follow the Linux instructions), but it isn't officially
+supported at the moment.
+
+Troubleshooting
+~~~~~~~~~~~~~~~
+
+Help, I ...
+
+* **... see a** :code:`pkg_resources.VersionConflict` **when I try to install
+  grpc**
+
+  This is likely because :code:`pip` doesn't own the offending dependency,
+  which in turn is likely because your operating system's package manager owns
+  it. You'll need to force the installation of the dependency:
+
+  :code:`pip install --ignore-installed $OFFENDING_DEPENDENCY`
+
+  For example, if you get an error like the following:
+
+  ::
+
+    Traceback (most recent call last):
+    File "<string>", line 17, in <module>
+     ...
+    File "/usr/lib/python2.7/dist-packages/pkg_resources.py", line 509, in find
+      raise VersionConflict(dist, req)
+    pkg_resources.VersionConflict: (six 1.8.0 (/usr/lib/python2.7/dist-packages), Requirement.parse('six>=1.10'))
+
+  You can fix it by doing:
+
+  ::
+
+    sudo pip install --ignore-installed six
+
+* **... see compiler errors on some platforms when either installing from source or from the source distribution**
+
+  If you see
+
+  ::
+
+    /tmp/pip-build-U8pSsr/cython/Cython/Plex/Scanners.c:4:20: fatal error: Python.h: No such file or directory
+    #include "Python.h"
+                    ^
+    compilation terminated.
+
+  You can fix it by installing `python-dev` package. i.e
+
+  ::
+
+    sudo apt-get install python-dev
+
+  If you see something similar to:
+
+  ::
+
+    third_party/protobuf/src/google/protobuf/stubs/mathlimits.h:173:31: note: in expansion of macro 'SIGNED_INT_MAX'
+    static const Type kPosMax = SIGNED_INT_MAX(Type); \\
+                               ^
+  And your toolchain is GCC (at the time of this writing, up through at least
+  GCC 6.0), this is probably a bug where GCC chokes on constant expressions
+  when the :code:`-fwrapv` flag is specified. You should consider setting your
+  environment with :code:`CFLAGS=-fno-wrapv` or using clang (:code:`CC=clang`).