r/collectd-version: Add OS version plugin

The `collectd-version` script uses the *collectd* UNIX socket to send
custom values to *collectd* to track the OS version.  Since these values
obviously cannot change while the system is running, the values are
specified with a very long interval.  This avoids having to continuously
insert the values, either with a long-running process or by repeatedly
running a script.  The values only need to be inserted once when
*collectd* starts.

roles/collectd-version/tasks/main.yml

@@ -0,0 +1,32 @@
+- name: ensure collectd-version script is installed
+  copy:
+    src: collectd-version.py
+    dest: /usr/local/libexec/collectd-version
+    mode: 'u=rwx,go=rx'
+  notify: restart collectd
+  tags:
+  - install
+
+- name: ensure collectd-version.service systemd unit exists
+  copy:
+    src: collectd-version.service
+    dest: /etc/systemd/system/
+    mode: 'u=rw,go=rx'
+  notify:
+  - reload systemd
+  - restart collectd-version
+  tags:
+  - systemd
+
+- name: ensure collectd-version service starts automatically
+  service:
+    name: collectd-version
+    enabled: true
+  tags:
+  - service
+- name: ensure collectd-version service is started
+  service:
+    name: collectd-version
+    state: started
+  tags:
+  - service