openqa/worker: disable aarch64-02 with a special worker class

openqa-aarch64-02.qa is broken in some very mysterious way:
https://pagure.io/fedora-infrastructure/issue/8750
until we can figure that out, this should prevent it picking up
normal jobs, but let us manually target a job at it whenever we
need to for debugging.

Signed-off-by: Adam Williamson <awilliam@redhat.com>

inventory/host_vars/openqa-aarch64-02.qa.fedoraproject.org

@@ -30,3 +30,12 @@ tcp_ports: ['20013', '20023', '20033', '20043', '20053', '20063', '20073', '2008
 
 # has an HW RNG, so let's have rngd
 openqa_rngd: True
+
+# FIXME this box is suffering from a mysterious bug that prevents VMs
+# working properly:
+# https://pagure.io/fedora-infrastructure/issue/8750
+# this means all openQA tests run on it fail. We cannot currently work
+# out why this is happening, so until we can, we will give it a special
+# worker class that prevents it picking up regular jobs, but allows us
+# to manually target it with jobs for debugging
+openqa_worker_class: aarch64-02-broken

roles/openqa/worker/tasks/main.yml

@@ -14,6 +14,8 @@
 # - openqa_rngd
 ##      string - if set to any value, rng-tools package will be
 ##               installed and rngd.service enabled/started
+# - openqa_worker_class
+##      string - custom WORKER_CLASS value for workers.ini
 
 - name: Install required packages (testing)
   package:

roles/openqa/worker/templates/workers.ini.j2

@@ -1,6 +1,8 @@
 [global]
 HOST = http://{{ openqa_hostname|default('localhost') }}
-{% if openqa_tap is defined and openqa_tap %}
+{% if openqa_worker_class is defined %}
+WORKER_CLASS = {{ openqa_worker_class }}
+{% elif openqa_tap is defined and openqa_tap %}
 {% if ansible_architecture == 'ppc64' or ansible_architecture == 'ppc64le' %}
 WORKER_CLASS = tap,qemu_ppc64le,qemu_ppc64
 {% elif ansible_architecture == 'aarch64' %}