[prometheus] use dig lookup for adm ip

plays/monitoring.yml

 #!/usr/bin/env ansible-playbook
 ---
-# Set variable adm_iface for all servers
-- hosts: server
-  tasks:
-    - name: Register adm interface in adm_iface variable
-      shell: set -o pipefail && grep adm /sys/class/net/*/ifalias | sed "s|/sys/class/net/||" | sed "s|/ifalias:.*||"
-      register: adm_iface
-      check_mode: false
-      changed_when: true
-      args:
-        executable: /bin/bash
-
 # Deploy Prometheus and Grafana on monitoring server
 - hosts: fyre.adm.crans.org
   vars:

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

@@ -4,7 +4,7 @@
 # Due to shell scaping, to pass backslashes for regexes, you need to double
 # them (\\d for \d). If running under systemd, you need to double them again
 # (\\\\d to mean \d), and escape newlines too.
-ARGS="--web.listen-address={{ hostvars[inventory_hostname]['ansible_' + adm_iface.stdout].ipv4.address }}:9100"
+ARGS="--web.listen-address={{ lookup('dig', ansible_host) }}:9100"
 
 # Prometheus-node-exporter supports the following options:
 #