CI: Fix overcloud and seed VM jobs on vexxhost clouds

This partially reverts commit 47bbb96b29ab30764d6220cdd43e63a1d2072533
which triggered a retry on vexxhost clouds.

The issue was introduced in Ie8fd965165e8d347d27528a2c16d0647e412ccdc,
which applied some fixes for CentOS 8.3, and inadvertently removed
the Tenks variable that forces the use of qemu for 'bare metal' VMs.
This lead to autodetection of KVM, which does not work well when nested
in all CI cloud providers.

This change fixes the issue by forcing the use of qemu for the overcloud
once more. It also adds a similar option for the seed VM job.

Change-Id: I6bc8da2b8da903e09b97df8cd95c68a562c11db9

dev/tenks-deploy-config-compute.yml

@@ -38,6 +38,10 @@ deploy_ramdisk: ipa.initramfs
 # container. Tenks will install libvirt client packages.
 libvirt_host_install_daemon: false
 
+# Nested virtualisation is not working well in CI currently. Force the use of
+# QEMU.
+libvirt_vm_engine: "qemu"
+
 # QEMU may not be installed on the host, so set the path and avoid
 # autodetection.
 libvirt_vm_emulator: "/usr/libexec/qemu-kvm"

playbooks/kayobe-overcloud-base/pre.yml

@@ -3,12 +3,6 @@
   environment:
     KAYOBE_CONFIG_SOURCE_PATH: "{{ kayobe_config_src_dir }}"
   tasks:
-    # FIXME(mgoddard): work out what's going wrong here.
-    - name: Fail if running on Vexxhost infra
-      fail:
-        msg: Baremetal tests fail on vexxhost - roll the dice again
-      when: "'vexxhost' in ansible_hostname"
-
     # NOTE(mgoddard): Use the name zz-overrides.yml to ensure this takes
     # precedence over the standard config files.
     - name: Ensure kayobe-config override config file exists

playbooks/kayobe-overcloud-upgrade-base/pre.yml

@@ -1,12 +1,6 @@
 ---
 - hosts: primary
   tasks:
-    # FIXME(mgoddard): work out what's going wrong here.
-    - name: Fail if running on Vexxhost infra
-      fail:
-        msg: Baremetal tests fail on vexxhost - roll the dice again
-      when: "'vexxhost' in ansible_hostname"
-
     # NOTE(mgoddard): Use the name zz-overrides.yml to ensure this takes
     # precedence over the standard config files.
     - name: Ensure kayobe-config override config file exists

playbooks/kayobe-seed-vm-base/overrides.yml.j2

@@ -18,6 +18,10 @@ pip_upper_constraints_file: "/tmp/upper-constraints.txt"
 # enabled. Don't fail if it's disabled.
 libvirt_host_require_vt: false
 
+# Nested virtualisation is not working well in CI currently. Force the use of
+# QEMU.
+libvirt_vm_engine: "qemu"
+
 # Use the CI infra's PyPI mirror.
 pip_local_mirror: true
 pip_index_url: "http://{{ zuul_site_mirror_fqdn }}/pypi/simple"

playbooks/kayobe-seed-vm-base/pre.yml

@@ -3,12 +3,6 @@
   environment:
     KAYOBE_CONFIG_SOURCE_PATH: "{{ kayobe_config_src_dir }}"
   tasks:
-    # FIXME(mgoddard): work out what's going wrong here.
-    - name: Fail if running on Vexxhost infra
-      fail:
-        msg: Seed VM tests fail on vexxhost - roll the dice again
-      when: "'vexxhost' in ansible_hostname"
-
     # NOTE(mgoddard): Use the name zz-overrides.yml to ensure this takes
     # precedence over the standard config files.
     - name: Ensure kayobe-config override config file exists