prometheus: add blackbox exporter

roles/prometheus/defaults/main.yml

@@ -12,3 +12,5 @@ prometheus_install_webhook: false
 prometheus_install_grafana: false
 
 alertmanager_storage_retention: "{{ prometheus_storage_retention }}"
+
+prometheus_ping_hosts: []

roles/prometheus/meta/argument_specs.yml

@@ -110,6 +110,13 @@ argument_specs:
                 type: str
                 required: true
 
+      prometheus_ping_hosts:
+        description: List of hosts to gather ping metrics for using prometheus blackbox exporter
+        type: list
+        required: false
+        default: []
+        elements: str
+
       # All options after this will be passed directly to the container role
       docker_service_suffix:
         description: "Passed to container role"

roles/prometheus/tasks/main.yml

@@ -45,6 +45,19 @@
       - name: prometheus
   when: prometheus_install_webhook
 
+- name: Blackbox exporter for prometheus
+  include_role:
+    name: container
+  vars:
+    docker_service: blackbox_exporter
+    docker_image: prom/blackbox-exporter
+    reverse_proxy_type: none
+    docker_mounts:
+      - template: blackbox_exporter.yml
+        path: /etc/blackbox_exporter/config.yml
+    docker_networks:
+      - name: prometheus
+
 - name: Grafana container for prometheus
   include_role: 
     name: grafana

roles/prometheus/templates/blackbox_exporter.yml.j2

@@ -0,0 +1,8 @@
+---
+
+modules:
+  icmp:
+    prober: icmp
+    timeout: 5s
+    icmp:
+      preferred_ip_protocol: "ip4"

roles/prometheus/templates/prometheus.yml.j2

@@ -26,6 +26,35 @@ scrape_configs:
     static_configs:
       - targets: ["localhost:9090"]
 
+  - job_name: "blackbox"
+    static_configs:
+      - targets: ["blackbox_exporter:9115"]
+
+{% if prometheus_ping_hosts | length > 0 %}
+  - job_name: "icmp"
+    metrics_path: "/probe"
+    params:
+      module: ["icmp"]
+    static_configs:
+      - targets:
+{% for host in prometheus_ping_hosts %}
+          - "{{ host.name }}::{{ host.type | default('monitored') }}"
+{% endfor %}
+    relabel_configs:
+      - source_labels: [__address__]
+        regex: '(.+)::(.+)'
+        target_label: __param_target
+        replacement: '${1}'
+      - source_labels: [__address__]
+        regex: '(.+)::(.+)'
+        target_label: host_type
+        replacement: '${2}'
+      - source_labels: [__param_target]
+        target_label: instance
+      - target_label: __address__
+        replacement: blackbox_exporter:9115
+{%- endif %}
+
 {% if prometheus_hcloud_enabled %}
   - job_name: hcloud
     hetzner_sd_configs: