Add randomized suffix to runner names

BPF CI runners went down recently due to a problem caused by "Runner
not found" error returned from a github broker service [1].

It appears that this error may be triggered by the fact that runner
names are reused for "different" runners from the perspective of
github. In BPF CI we use ephemeral runners which re-register every
time a corresponding runner container is restarted.

Whatever the root cause, a working mitigation is to use unique runner
names. Fortunately, entrypoint.sh [1] already has the logic of
generating a random suffix, and we only need to set relevant
environment variables.

Additionally, set RestartPreventExitStatus=199 in the runner systemd
service to prevent error looping in case we run out of tokens [2].

[1] https://github.com/myoung34/docker-github-actions-runner/blob/2.323.0/entrypoint.sh
[2] kernel-patches/runner#75

Signed-off-by: Ihor Solodrai <[email protected]>

Author: theihor

ansible/roles/runner/tasks/main.yml

@@ -105,7 +105,8 @@
       RUNNER_SCOPE=org
       ORG_NAME={{ item.0.name }}
       {% endif %}
-      RUNNER_NAME={{ runner_name_prefix }}-{{ 'worker-%02d' | format(item.1) }}
+      RUNNER_NAME_PREFIX={{ runner_name_prefix }}-{{ 'worker-%02d' | format(item.1) }}
+      RANDOM_RUNNER_SUFFIX=true
       DISABLE_AUTO_UPDATE=true
   loop: "{{ runners | subelements('workers') }}"
 
@@ -139,6 +140,7 @@
       [Service]
       TimeoutStartSec=0
       Restart=always
+      RestartPreventExitStatus=199
       EnvironmentFile={{ runner_base_dir }}/runner_unit.env
       # Optionally loaded file. Use this to override per runner environment
       EnvironmentFile=-{{ runner_base_dir }}/runner_unit-%i.env