Add env var file for node exporter

enable a file that can set a var for command line args to node exporter
to be able to add textfile collectors or otherwise configure node
exporter on a machine

README.md

@@ -7,7 +7,7 @@ Set up common prometheus exporter configurations
 ```
 - src: [email protected]:smartlogic/ansible-role-prometheus-exporters
   name: prometheus-exporters
-  version: 1.0.0
+  version: 1.1.0
 ```
 
 ## Requirements
@@ -58,6 +58,7 @@ These ports should be opened to the prometheus server based on the enabled expor
 
 - `node_exporter_version` - Which version of node exporter to download
 - `node_exporter_checksum` - The checksum for the version of node exporter
+- `node_exporter_env_file` - A file, default to empty, can be in your playbook directory, that is the env file for the exporter, used to set `NODE_EXPORTER_ARGS` for command line args or other env vars for node exporter
 - `redis_exporter_version` - Which version of redis_exporter to download
 - `redis_exporter_checksum` - The checksum for the version of redis_exporter
 - `redis_addr` - The address of the redis instance to monitor

defaults/main.yml

@@ -1,6 +1,7 @@
 ---
 node_exporter_version: 1.5.0
 node_exporter_checksum: af999fd31ab54ed3a34b9f0b10c28e9acee9ef5ac5a5d5edfdde85437db7acbb
+node_exporter_env_file: "node_exporter.env"
 
 redis_exporter_version: 0.15.0
 redis_exporter_checksum: 170458f8c9e1588861b1584451cfc636b1339b4cf495f82396f03e474d6e626f

tasks/node_exporter.yml

@@ -48,6 +48,15 @@
   become: yes
   become_user: prometheus
 
+- name: Template out the env file
+  template:
+    src: {{ node_exporter_env_file }}
+    dest: /etc/prometheus-node-exporter
+    mode: 0644
+  become: yes
+  notify:
+    - restart node_exporter
+
 - name: Template out the service file
   template:
     src: node_exporter.service.j2

tasks/statsd_exporter.yml

@@ -54,6 +54,8 @@
     dest: /home/prometheus/statsd_exporter/mapping.yml
   become: yes
   become_user: prometheus
+  notify:
+    - restart statsd_exporter
 
 - name: Template out the service file
   template:

templates/node_exporter.service.j2

@@ -6,7 +6,9 @@ After=network-online.target
 User=prometheus
 Restart=on-failure
 WorkingDirectory=/home/prometheus/node_exporter/{{ node_exporter_version }}/node_exporter
-ExecStart=/home/prometheus/node_exporter/{{ node_exporter_version }}/node_exporter/node_exporter
+EnvironmentFile=-/etc/prometheus-node-exporter
+ExecStart=/home/prometheus/node_exporter/{{ node_exporter_version }}/node_exporter/node_exporter $NODE_EXPORTER_ARGS
+ExecReload=/bin/kill -HUP $MAINPID
 
 [Install]
 WantedBy=multi-user.target