Add option to install EPEL prereq for os_images

Author: Alex-Welsh

roles/os_images/README.md

@@ -25,6 +25,10 @@ Role Variables
 `os_images_package_dependencies_extra`: List of additional packages to install
 on the build host.
 
+`os_images_install_epel_repo`: Whether to enable the CRB repository and install
+the EPEL repository before installing packages on the build host. This is
+disabled by default to prevent conflicts arising from the EPEL repository.
+
 `os_images_cache`: a path to a directory in which to cache build artefacts.
 It defaults to `~/disk_images`
 `NOTE`: new images will NOT be built, even if changes are made in config, if an image

roles/os_images/defaults/main.yml

@@ -1,6 +1,9 @@
 ---
 # List of additional host package dependencies to install.
 os_images_package_dependencies_extra: []
+# Whether to enable the CRB repository and install the EPEL repository before
+# installing packages.
+os_images_install_epel_repo: false
 # Path to virtualenv in which to install python dependencies to upload images.
 os_images_venv:
 # Path to virtualenv in which to install DIB to build images.

roles/os_images/tasks/prereqs.yml

@@ -2,6 +2,24 @@
 - name: Include OS family-specific variables
   ansible.builtin.include_vars: "{{ ansible_facts.os_family }}.yml"
 
+- name: Ensure CRB repository is enabled
+  community.general.dnf_config_manager:
+    name: crb
+    state: enabled
+  when:
+    - os_images_install_epel_repo | bool
+    - ansible_facts.os_family == "RedHat"
+  become: true
+
+- name: Ensure EPEL repository is installed
+  ansible.builtin.dnf:
+    name: epel-release
+    state: present
+  when:
+    - os_images_install_epel_repo | bool
+    - ansible_facts.os_family == "RedHat"
+  become: true
+
 - name: Ensure required packages are installed
   ansible.builtin.package:
     name: "{{ (os_images_package_dependencies + os_images_package_dependencies_extra) | select | list }}"