Add prometheus node exporter

docs/all.md

@@ -2,7 +2,8 @@
 These variables might be required by multiple roles and need to be defined. Example values below.
 
 ```
-admin_email: 'admin@domain.tld'
+admin_email: admin@domain.tld
+local_network: 10.0.0.0/8
 ```
 
 # Optional variables

roles/prometheus_node_exporter/handlers/main.yml

@@ -0,0 +1,6 @@
+---
+
+- name: restart prometheus-node-exporter
+  systemd:
+    name: prometheus-node-exporter
+    state: restarted

roles/prometheus_node_exporter/meta/argument_specs.yml

@@ -0,0 +1,10 @@
+---
+
+argument_specs:
+  main:
+    short_description: Prometheus node exporter
+    options:
+      local_network:
+        description: The local ipv4 network block, listen address is taken from this block
+        type: str
+        required: true

roles/prometheus_node_exporter/tasks/main.yml

@@ -0,0 +1,12 @@
+---
+
+- name: Install prometheus node exporter
+  apt:
+    name: prometheus-node-exporter
+
+- name: Set prometheus options in /etc/default/prometheus-node-exporter
+  template:
+    src: templates/prometheus-node-exporter.j2
+    dest: /etc/default/prometheus-node-exporter
+    mode: 0644
+  notify: restart prometheus-node-exporter

roles/prometheus_node_exporter/templates/prometheus-node-exporter.j2

@@ -0,0 +1 @@
+ARGS="--web.listen-address {{ (ansible_all_ipv4_addresses | ansible.utils.ipaddr(local_network))[0] }}:9100 --collector.logind --collector.systemd --collector.processes"