Fix virtualbmc installation after release of cryptography 3.4

Installing virtualbmc system-wide on CentOS 8 fails with:

    ModuleNotFoundError: No module named 'setuptools_rust'

This error appeared following the release of cryptography 3.4, which now
includes Rust code. It can be installed without Rust using a Python
wheel, but only with more recent pip than version 9.0.3 available as RPM
on CentOS 8. The cryptography bug report [1] recommends pip>=19.1.1.

Also ignore PyYAML when installing system-wide to avoid conflicts with
an existing RPM package installation.

[1] https://github.com/pyca/cryptography/issues/5753

Change-Id: Ibd61e090611b3b7a7e0670c854362b512454bf3c
Story: 2008607
Task: 41788

ansible/roles/virtualbmc-daemon/tasks/main.yml

@@ -18,12 +18,25 @@
   retries: 3
   become: true
 
+# NOTE(priteau): We need a recent pip to install the latest cryptography
+# library. See https://github.com/pyca/cryptography/issues/5753
+- name: Ensure a recent version of pip is installed
+  pip:
+    name: "pip>=19.1.1"
+    virtualenv: "{{ vbmcd_virtualenv_path or omit }}"
+  become: "{{ not vbmcd_virtualenv_path }}"
+
 - name: Ensure Python requirements are installed
   pip:
     name:
       - "virtualbmc>=1.4.0{% if ansible_python.version.major == 2 %},<2{% endif %}"
+    # NOTE(priteau): Ignore PyYAML when installing system-wide to avoid the
+    # following error: Cannot uninstall 'PyYAML'. It is a distutils installed
+    # project and thus we cannot accurately determine which files belong to it
+    # which would lead to only a partial uninstall.
     extra_args: >-
       -c {{ vbmcd_python_upper_constraints_url }}
+      {% if not vbmcd_virtualenv_path %}--ignore-installed PyYAML{% endif %}
     virtualenv: "{{ vbmcd_virtualenv_path or omit }}"
   register: result
   until: result is success

releasenotes/notes/virtualbmc-cryptography-03d62a3d1e965197.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    Fixes system-wide installation of virtualbmc following the release of
+    version 3.4 of the cryptography package. See `story 2008607
+    <https://storyboard.openstack.org/#!/story/2008607>`__ for details.