Add support for Debian Bullseye (11) as host distro

Makes nova-libvirt container always run in 'host' CgroupnsMode
to ensure it works.

Change-Id: I75105baf434977c68bc5c8ca1f5213e602c52c8c

ansible/roles/nova-cell/defaults/main.yml

@@ -8,6 +8,7 @@ nova_cell_services:
     enabled: "{{ nova_compute_virt_type in ['kvm', 'qemu'] }}"
     image: "{{ nova_libvirt_image_full }}"
     pid_mode: "host"
+    cgroupns_mode: "host"
     privileged: True
     volumes: "{{ nova_libvirt_default_volumes + nova_libvirt_extra_volumes }}"
     dimensions: "{{ nova_libvirt_dimensions }}"

ansible/roles/nova-cell/handlers/main.yml

@@ -100,6 +100,7 @@
     name: "{{ service.container_name }}"
     image: "{{ service.image }}"
     pid_mode: "{{ service.pid_mode | default('') }}"
+    cgroupns_mode: "{{ service.cgroupns_mode | default(omit) }}"
     privileged: "{{ service.privileged | default(False) }}"
     volumes: "{{ service.volumes|reject('equalto', '')|list }}"
     dimensions: "{{ service.dimensions }}"

ansible/roles/nova-cell/tasks/check-containers.yml

@@ -8,6 +8,7 @@
     image: "{{ item.value.image }}"
     environment: "{{ item.value.environment|default(omit) }}"
     pid_mode: "{{ item.value.pid_mode|default('') }}"
+    cgroupns_mode: "{{ item.value.cgroupns_mode|default(omit) }}"
     ipc_mode: "{{ item.value.ipc_mode|default(omit) }}"
     privileged: "{{ item.value.privileged|default(False) }}"
     volumes: "{{ item.value.volumes|reject('equalto', '')|list }}"

ansible/roles/prechecks/vars/main.yml

@@ -13,6 +13,7 @@ host_os_distributions:
     - "8"
   Debian:
     - "buster"
+    - "bullseye"
   RHEL:
     - "8"
   Ubuntu:

releasenotes/notes/debian-bullseye-host-adc7778d7103b84f.yaml

+---
+features:
+  - |
+    Supports Debian Bullseye (11) as host distribution.