Symlink ceph libraries out of venv

Currently, we install python-rados and python-rbd via apt when ceph
integration is enabled, which causes issues when venvs are used in the
environment.  This commit adds a temporary work-around by creating
symlinks in the venv to the installed libraries outside.

There is currently a ceph issue [1] in progress to make this possible,
and once this has been completed we can update ceph_client role to
install python packages instead.

[1] http://tracker.ceph.com/issues/5900

Change-Id: Ia7a3ceae002054fd75e0305892b20ce1143f8dcc
Closes-Bug: #1509837

tasks/nova_compute_kvm_install.yml

@@ -77,6 +77,28 @@
     - nova-install
     - nova-pip-packages
 
+# TODO(mattt): remove once ceph_client role can install ceph packages from pypi
+# This is being done as a temporary workaround since we currently cannot obtain
+#  ceph-related libraries from pypi.  There is work in progress [1] to address
+#  this.
+#  [1] http://tracker.ceph.com/issues/5900
+- name: Link ceph libraries into the venv
+  file:
+    src: "{{ item.name }}"
+    dest: "{{ nova_venv_bin | dirname }}/lib/python2.7/site-packages/{{ item.name | basename }}"
+    state: "{{ item.state }}"
+    force: "yes"
+  with_items:
+    - { state: link, name: "/usr/lib/python2.7/dist-packages/rados.py" }
+    - { state: link, name: "/usr/lib/python2.7/dist-packages/rbd.py" }
+  when:
+    - nova_venv_enabled | bool
+    - inventory_hostname in groups['nova_compute']
+    - (cinder_backends_rbd_inuse|bool or nova_libvirt_images_rbd_pool is defined)
+  tags:
+    - nova-install
+    - nova-pip-packages
+
 - name: Install pip packages (no venv)
   pip:
     name: "{{ item }}"