setup.py: Add plugin requirements as extraschandan/extras-require

Currently, there isn't an easy way to install BuildStream along with its
plugin dependencies, using pip.

Add plugin requirements as extras
(https://setuptools.readthedocs.io/en/latest/setuptools.html#declaring-extras-optional-features-with-their-own-dependencies)
so that they can be installed by specifying the relevant extras to
`pip`.

This repository has only one plugin - `deb` source - that has external
dependencies, i.e. `arpy`. With this patch, one should be able to
install BuildStream and dependencies for the `deb` plugin using
something like `pip instal BuildStream[deb]`.

1 files changed, 9 insertions, 0 deletions

diff --git a/setup.py b/setup.py
index 19779fb69..c6dc2eec7 100755
--- a/setup.py
+++ b/setup.py
@@ -301,6 +301,14 @@ with open('requirements/dev-requirements.in') as dev_reqs:
 with open('requirements/requirements.in') as install_reqs:
     install_requires = install_reqs.read().splitlines()
 
+# Dependencies of plugins. These are not strict requirements for installing
+# BuildStream so add them as extras.
+#
+# This is a mapping between the plugin name and its dependencies.
+extras_require = {
+    "deb": ["arpy"],
+}
+
 #####################################################
 #     Prepare package description from README       #
 #####################################################
@@ -469,6 +477,7 @@ setup(name='BuildStream',
       install_requires=install_requires,
       entry_points=bst_install_entry_points,
       tests_require=dev_requires,
+      extras_require=extras_require,
       ext_modules=cythonize(
           BUILD_EXTENSIONS,
           compiler_directives={