Add prometheus role

Configured to include job definitions from /etc/prometheus/conf.d/*.yml.

roles/prometheus/tasks/main.yml

@@ -0,0 +1,21 @@
+- name: Install packages
+  package:
+    name:
+      - prometheus
+
+- name: Create directory for prometheus configs
+  file:
+    path: /etc/prometheus/conf.d
+    state: directory
+
+- name: Configure prometheus
+  copy:
+    dest: /etc/prometheus/
+    src: prometheus.yml
+  notify: reload prometheus
+
+- name: Enable prometheus service
+  service:
+    name: prometheus
+    enabled: true
+    state: started