Add support for installing QEMU emulators

Set the libvirt_host_qemu_emulators to a list of architectures for which
to install QEMU system emulators.

Author: markgoddard

README.md

@@ -34,6 +34,11 @@ Technology (VT) is enabled in order to run this role. While this provides
 better VM performance, it may not be available in certain environments. The
 default value is `true`.
 
+`libvirt_host_qemu_emulators`: List of architectures for which to install QEMU
+system emulators, e.g.  `x86`. The default value is `['x86']` if
+`libvirt_host_require_vt` is `false`, otherwise the default value is an empty
+list.
+
 Dependencies
 ------------
 

defaults/main.yml

@@ -22,3 +22,6 @@ libvirt_host_networks: []
 # order to run this role. While this provides better VM performance, it may not
 # be available in certain environments.
 libvirt_host_require_vt: true
+
+# List of architectures for which to install QEMU system emulators, e.g. x86.
+libvirt_host_qemu_emulators: "{{ [] if libvirt_host_require_vt | bool else ['x86'] }}"

tasks/install.yml

@@ -11,6 +11,23 @@
     - qemu-kvm
   become: True
 
+# NOTE: QEMU emulators are available in EPEL.
+- name: Ensure the EPEL repository is enabled
+  yum:
+    name: epel-release
+    state: installed
+  when: libvirt_host_qemu_emulators | length > 0
+  become: True
+
+- name: Ensure QEMU emulator packages are installed
+  yum:
+    name: "{{ package }}"
+    state: installed
+  with_items: "{{ libvirt_host_qemu_emulators }}"
+  become: True
+  vars:
+    package: "qemu-system-{{ item }}"
+
 - name: Ensure the libvirt daemon is started and enabled
   service:
     name: libvirtd

tasks/validate.yml

@@ -5,14 +5,18 @@
   failed_when: False
   register: result
 
+- name: Set a fact about whether Virtualization Technology (VT) is enabled
+  set_fact:
+    libvirt_host_vt_enabled: "{{ result.rc == 0 }}"
+
 - name: Notify if Virtualization Technology (VT) is disabled
   debug:
     msg: >
       Virtualization Technology (VT) is currently disabled. Please enable VT
       before running this role again.
   when:
     - not libvirt_host_require_vt | bool
-    - result.rc != 0
+    - not libvirt_host_vt_enabled
 
 - name: Fail if Virtualization Technology (VT) is disabled
   fail:
@@ -21,4 +25,4 @@
       before running this role again.
   when:
     - libvirt_host_require_vt | bool
-    - result.rc != 0
+    - not libvirt_host_vt_enabled