Resolve common roles required for test

This change adds a common test role requirements file to the
preparation process whch will ensure all required common roles are
available prior to running tests.

As we move to use common roles throughout our deliverables this change
will help ensure we're not having to map complex common dependencies
throughout our supported roles, which is prone to human error and can
cause cascading failures throughout out stack should a requirement be
missed.

Change-Id: If3c57d5c864aee3a6bc461dead367eac7f3eede2
Signed-off-by: Kevin Carter <kevin.carter@rackspace.com>

test-ansible-env-prep.sh

@@ -176,16 +176,23 @@ fi
 
 # Download the Ansible role repositories if they are not present on the host.
 # This is ignored if there is no ansible-role-requirements file.
-if [ ! -d "${ANSIBLE_ROLE_DEP_DIR}" ] && [ -f "${ANSIBLE_ROLE_REQUIREMENTS_PATH}" ]; then
-   ansible-playbook -i ${ANSIBLE_INVENTORY} \
-         ${COMMON_TESTS_PATH}/get-ansible-role-requirements.yml \
-         -v
-   if [[ ! -e "${ANSIBLE_ROLE_DEP_DIR}/plugins" ]]; then
-     ln -s "${ANSIBLE_PLUGIN_DIR}" "${ANSIBLE_ROLE_DEP_DIR}/plugins"
-   fi
+if [[ ! -d "${ANSIBLE_ROLE_DEP_DIR}" ]]; then
+  # Download the common test Ansible role repositories.
+  ANSIBLE_ROLE_REQUIREMENTS_PATH=${COMMON_TESTS_PATH}/test-ansible-role-requirements.yml \
+    ansible-playbook -i ${ANSIBLE_INVENTORY} \
+    ${COMMON_TESTS_PATH}/get-ansible-role-requirements.yml \
+    -v
+
+  if [[ -f "${ANSIBLE_ROLE_REQUIREMENTS_PATH}" ]]; then
+     ansible-playbook -i ${ANSIBLE_INVENTORY} \
+           ${COMMON_TESTS_PATH}/get-ansible-role-requirements.yml \
+           -v
+    if [[ ! -e "${ANSIBLE_ROLE_DEP_DIR}/plugins" ]]; then
+      ln -s "${ANSIBLE_PLUGIN_DIR}" "${ANSIBLE_ROLE_DEP_DIR}/plugins"
+    fi
+  fi
 fi
 
-
 # If a role name is provided, replace the role in the roles folder with a link
 # to the current folder. This ensures that the test executes with the checked
 # out git repo.

test-ansible-role-requirements.yml

@@ -0,0 +1,17 @@
+---
+- name: systemd_service
+  src: https://git.openstack.org/openstack/ansible-role-systemd_service
+  scm: git
+  version: master
+- name: systemd_mount
+  src: https://git.openstack.org/openstack/ansible-role-systemd_mount
+  scm: git
+  version: master
+- name: systemd_networkd
+  src: https://git.openstack.org/openstack/ansible-role-systemd_networkd
+  scm: git
+  version: master
+- name: python_venv_build
+  src: https://git.openstack.org/openstack/ansible-role-python_venv_build
+  scm: git
+  version: master