Adding devpi_consumer role for Devstack

CHANGELOG.md

+- Role: devpi
+  - New role added to configure a devpi service as a pass-through cache for PyPI.
+
+- Role: devpi_consumer
+  - Added role to configure Python containers to use devpi for Docker Devstack
+
 - Role: xqueue
   - Remove S3_BUCKET and S3_PATH_PREFIX - they were deprecated prior to ginkgo
   - Remove SERVICE_VARIANT - it was copied from edxapp but never truly used (except to complicate things)

docker/plays/edxapp.yml

@@ -8,6 +8,7 @@
   roles:
     - common_vars
     - docker
+    - devpi_consumer
     - role: nginx
       nginx_sites:
       - lms

playbooks/roles/devpi_consumer/defaults/main.yml

+# Variables for the devpi_consumer role
+# This role allows a host to use the configured devpi server as a primary source for pip
+# Defaults are for Docker Devstack
+#
+
+# This should be a directory, pip.conf will be appended
+DEVPI_PIP_CONF_PATH: /root/.pip
+DEVPI_PIP_CONF_OWNER: root
+DEVPI_PIP_CONF_GROUP: root
+
+DEVPI_HOST: edx.devstack.devpi
+DEVPI_PORT: 3141
+
+# http or https
+#
+DEVPI_PROTOCOL: http
+
+# Use a leading slash, but no trailing slash here
+#
+DEVPI_INDEX: /root/pypi

playbooks/roles/devpi_consumer/tasks/main.yml

+- name: create pip conf directory
+  file:
+    path: "{{ DEVPI_PIP_CONF_PATH }}"
+    state: directory
+    owner: "{{ DEVPI_PIP_CONF_OWNER }}"
+    group: "{{ DEVPI_PIP_CONF_GROUP }}"
+  when: devstack is defined and devstack
+  tags:
+    - devstack
+    - devstack:install
+
+- name: write pip.conf to devstack
+  template:
+    src: "pip.conf.j2"
+    dest: "{{ DEVPI_PIP_CONF_PATH }}/pip.conf"
+    owner: "{{ DEVPI_PIP_CONF_OWNER }}"
+    group: "{{ DEVPI_PIP_CONF_GROUP }}"
+    mode: 0744
+  when: devstack is defined and devstack
+  tags:
+    - devstack
+    - devstack:install

playbooks/roles/devpi_consumer/templates/pip.conf.j2

+[global]
+index-url = {{ DEVPI_PROTOCOL }}://{{ DEVPI_HOST }}:{{ DEVPI_PORT }}{{ DEVPI_INDEX }}/+simple/
+
+# Enables failover to PyPI if devpi is broken
+extra-index-url = https://pypi.python.org/simple
+
+# This is necessary if you aren't using TLS on the DevPI host
+trusted-host = {{ DEVPI_HOST }}
+
+[search]
+index = {{ DEVPI_PROTOCOL }}://{{ DEVPI_HOST }}:{{ DEVPI_PORT }}{{ DEVPI_INDEX }}/