Make API server deps optional, move them to extras

This makes it so "pip install ara" would only install a minimal
amount of dependencies (pbr and requests as of this commit) required
for running the Ansible callback plugin as well as ara_record.

The server dependencies can be installed by running
"pip install ara[server]".

Fixes: https://github.com/ansible-community/ara/issues/36
Change-Id: I67769d28ec24cade7753230dffd0b049358af29a

README.rst

@@ -25,8 +25,8 @@ Here's how you can get started from scratch with default settings:
     python3 -m venv ~/.ara/virtualenv
     source ~/.ara/virtualenv/bin/activate
 
-    # Install Ansible and the required ARA projects
-    pip install ansible git+https://github.com/openstack/ara@feature/1.0
+    # Install Ansible, ARA and it's API server dependencies
+    pip install ansible git+https://github.com/openstack/ara@feature/1.0[server]
 
     # Tell Ansible to use the ARA callback plugin
     export ANSIBLE_CALLBACK_PLUGINS="$(python -m ara.setup.callback_plugins)"

ara/clients/offline.py

@@ -22,10 +22,14 @@ import logging
 import os
 import threading
 
-from django.core.handlers.wsgi import WSGIHandler
-from django.core.servers.basehttp import ThreadedWSGIServer, WSGIRequestHandler
-
 from ara.clients.http import AraHttpClient
+from ara.setup.exceptions import MissingDjangoException
+
+try:
+    from django.core.handlers.wsgi import WSGIHandler
+    from django.core.servers.basehttp import ThreadedWSGIServer, WSGIRequestHandler
+except ImportError as e:
+    raise MissingDjangoException from e
 
 
 class AraOfflineClient(AraHttpClient):

ara/server/__main__.py

@@ -19,11 +19,16 @@
 import os
 import sys
 
+from ara.setup.exceptions import MissingDjangoException
+
 
 def main():
     os.environ.setdefault("DJANGO_SETTINGS_MODULE", "ara.server.settings")
 
-    from django.core.management import execute_from_command_line
+    try:
+        from django.core.management import execute_from_command_line
+    except ImportError as e:
+        raise MissingDjangoException from e
 
     execute_from_command_line(sys.argv)
 

ara/server/wsgi.py

@@ -17,7 +17,12 @@
 
 import os
 
-from django.core.wsgi import get_wsgi_application
+from ara.setup.exceptions import MissingDjangoException
+
+try:
+    from django.core.wsgi import get_wsgi_application
+except ImportError as e:
+    raise MissingDjangoException from e
 
 os.environ.setdefault("DJANGO_SETTINGS_MODULE", "ara.server.settings")
 

ara/setup/exceptions.py

@@ -0,0 +1,22 @@
+#  Copyright (c) 2019 Red Hat, Inc.
+#
+#  This file is part of ARA Records Ansible.
+#
+#  ARA is free software: you can redistribute it and/or modify
+#  it under the terms of the GNU General Public License as published by
+#  the Free Software Foundation, either version 3 of the License, or
+#  (at your option) any later version.
+#
+#  ARA is distributed in the hope that it will be useful,
+#  but WITHOUT ANY WARRANTY; without even the implied warranty of
+#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#  GNU General Public License for more details.
+#
+#  You should have received a copy of the GNU General Public License
+#  along with ARA.  If not, see <http://www.gnu.org/licenses/>.
+
+
+class MissingDjangoException(Exception):
+    def __init__(self):
+        exc = "Unable to import Django: the server dependencies can be installed with 'pip install ara[server]'"
+        super().__init__(exc)

doc/source/installation.rst

@@ -3,22 +3,58 @@
 Installing ARA
 ==============
 
-Manually with pip
------------------
+Requirements and dependencies
+-----------------------------
 
 ARA should work on any Linux distributions as long as python3 is available.
 
-It is recommended to use a python `virtual environment <https://docs.python.org/3/tutorial/venv.html>`_
-in order to avoid conflicts with your Linux distribution python packages::
+Since ARA provides Ansible plugins to record data, it should be installed
+wherever Ansible is running from so that Ansible can use those plugins.
+The API server does not require to run on the same machine as Ansible.
 
-    # Create a virtual environment
-    python3 -m venv ~/.ara/venv
+By default, only the client and plugin dependencies are installed.
+This lets users record and send data to a remote API server without requiring
+that the API server dependencies are installed.
 
-    # Install ARA 1.0 from source
-    ~/.ara/venv/bin/pip install git+https://git.openstack.org/openstack/ara@feature/1.0
+If you are standing up an API server or if your use case is about recording
+data locally or offline, the required dependencies can be installed
+automatically by suffixing ``[server]`` to your pip install commands.
 
-Using Ansible roles
--------------------
+Installing from PyPi or from source
+-----------------------------------
+
+First, it is recommended to use a python `virtual environment <https://docs.python.org/3/tutorial/venv.html>`_
+in order to avoid conflicts with your Linux distribution python packages.
+
+.. code-block:: bash
+
+    python3 -m venv ~/.ara/virtualenv
+
+To install the latest pre-release for ARA 1.0 from PyPi_:
+
+.. code-block:: bash
+
+    # With the API server dependencies
+    ~/.ara/virtualenv/bin/pip install --pre ara[server]
+
+    # Without the API server dependencies
+    ~/.ara/virtualenv/bin/pip install --pre ara
+
+Installing from source is possible by using the
+`feature/1.0 <https://github.com/ansible-community/ara@feature/1.0>`_ branch:
+
+.. code-block:: bash
+
+    # With the API server dependencies
+    ~/.ara/virtualenv/bin/pip install git+https://github.com/ansible-community/ara@feature/1.0[server]
+
+    # Without the API server dependencies
+    ~/.ara/virtualenv/bin/pip install git+https://github.com/ansible-community/ara@feature/1.0
+
+.. _PyPi: https://pypi.org/project/ara/
+
+With Ansible roles
+------------------
 
 Two roles are built-in to help users configure their API and web deployments:
 

requirements.txt

@@ -1,9 +1,3 @@
 pbr!=2.1.0,>=2.0.0 # Apache-2.0
 
-Django>=2.1.5
-djangorestframework>=3.9.1
-django-cors-headers
-django-filter
-dynaconf[yaml]
 requests>=2.14.2
-whitenoise

roles/ara_api/tasks/install/source.yaml

@@ -24,7 +24,7 @@
 
 - name: Install ara
   pip:
-    name: "{{ ara_api_source_checkout }}"
+    name: "{{ ara_api_source_checkout }}[server]"
     state: present
     virtualenv: "{{ ara_api_venv | bool | ternary(ara_api_venv_path, omit) }}"
     virtualenv_python: python3

roles/ara_tests/tasks/main.yaml

@@ -62,7 +62,7 @@
 
 - name: Install ARA from source in virtual environment
   pip:
-    name: "{{ _ara_tests_repository }}"
+    name: "{{ _ara_tests_repository }}[server]"
     state: present
     virtualenv: "{{ ara_tests_virtualenv }}"
     virtualenv_python: python3

setup.cfg

@@ -31,6 +31,15 @@ packages =
 console_scripts =
     ara-manage = ara.server.__main__:main
 
+[extras]
+server=
+    Django>=2.1.5
+    djangorestframework>=3.9.1
+    django-cors-headers
+    django-filter
+    dynaconf[yaml]
+    whitenoise
+
 [build_sphinx]
 source-dir = doc/source
 build-dir = doc/build

tox.ini

@@ -10,6 +10,7 @@ usedevelop = True
 install_command = pip install -U {opts} {packages} -c{env:CONSTRAINTS_FILE:/dev/null}
 setenv = VIRTUAL_ENV={envdir}
 deps = -r{toxinidir}/test-requirements.txt
+extras = server
 
 [testenv:venv]
 commands = {posargs}