Fix distro installs on Ubuntu

Beginning in the Stein release, Ubuntu distro packages are now using
Python3. This requires additionally installing and using the uwsgi
python3 plugin.

Install the 'python3-mistral' package instead of individual service
packages since they provide service config files that conflict
with the ones OSA provides.

Depends-On: https://review.opendev.org/#/c/662571
Change-Id: I4b9846a12382f3ef4acdffce8a6f2338ed45d6ff

templates/mistral-uwsgi.ini.j2

@@ -6,6 +6,9 @@ gid = {{ mistral_system_group_name }}
 {% if mistral_install_method == 'source' %}
 virtualenv = /openstack/venvs/mistral-{{ mistral_venv_tag }}
 {% endif %}
+{% if mistral_install_method == 'distro' and (ansible_os_family | lower) == 'debian' %}
+plugin = python3
+{% endif %}
 wsgi-file = {{ mistral_bin }}/{{ item.wsgi_name }}
 http = {{ item.uwsgi_bind_address }}:{{ item.uwsgi_port }}
 
@@ -23,4 +26,4 @@ logfile-chmod = 644
 pidfile = /var/run/{{ item.service_name }}/{{ item.service_name }}.pid
 
 # Avoid filling up the logs with health check requests from haproxy.
-route-user-agent = ^osa-haproxy-healthcheck$ donotlog:
+route-user-agent = ^osa-haproxy-healthcheck$ donotlog:

vars/debian.yml

@@ -21,9 +21,9 @@ mistral_distro_packages:
   - libpython2.7
 
 mistral_service_distro_packages:
-  - mistral-api
-  - mistral-engine
-  - mistral-executor
+  - python3-mistral
+  - uwsgi
+  - uwsgi-plugin-python3
 
 mistral_oslomsg_amqp1_distro_packages:
   - libsasl2-modules