ansible: Set runner_name_prefix to the host's hostname by default

For Amazon Linux running in EC2, the prefix get overwritten by the
instance ID instead.
We try to do this in a block where failure are ignored.
This code is only run when the host OS is Amazon Linux. Failure to
access the EC2 endpoint to discover the host metadata will result in the
host defaulting to use its hostname. This is useful when running an
Amazon Linux host in a VM for local testing.

Signed-off-by: Manu Bretelle <[email protected]>

Author: chantra

ansible/roles/runner/tasks/main.yml

@@ -60,25 +60,29 @@
     runners: "{{ runners|default([]) + [ {'gh_app_id': 0, 'normalized': item.name | replace('/','-'), 'workers': range(item.instances) | list }  | combine(item) ] }}"
   with_items: "{{ runner_repo_list }}"
 
-- name: Generate runner environment file
+- name: Set runner name prefix
+  set_fact:
+    runner_name_prefix: "{{ '%s-' | format(runner_prefix) if runner_prefix }}{{ ansible_hostname }}"
+
+# When running on Amazon Linux hosts, we override the runner_name_prefix with the ec2's instance ID.
+# When testing in Amazon Linux VMs, the `Load ec2 metadata facts` task will fail and we will fallback
+# on using hostname.
+- name: Set runner_name_prefix to instance ID for Amazon hosts
   block:
     - name: Load ec2 metadata facts
       amazon.aws.ec2_metadata_facts:
 
-    - name: Set runner name prefix
+    - name: Set runner name prefix with instance ID
       set_fact:
         runner_name_prefix: "{{ '%s-' | format(runner_prefix) if runner_prefix }}{{ ansible_ec2_instance_id }}"
-
-  rescue:
-    - name: Set runner name prefix
-      set_fact:
-        runner_name_prefix: "{{ '%s-' | format(runner_prefix) if runner_prefix }}{{ ansible_hostname }}"
+  when: ansible_distribution == 'Amazon'
+  ignore_errors: yes
 
 # Build docker images
 - include_tasks: main-s390x.yml
   when: ansible_architecture == 's390x'
 
-- name: Generate runner env outside AWS
+- name: Generate runner env
   become: yes
   ansible.builtin.copy:
     dest: "{{ runner_base_dir }}/actions-runner-{{ item.0.normalized }}-{{ 'worker-%02d.env' | format(item.1) }}"