add promtail support

defaults/main.yml

@@ -240,6 +240,8 @@ prometheus_agent:
               preferred_ip_protocol: ip4
             prober: icmp
       jobs: {}
+    promtail:
+      enable: False
   scrape_timeout: ~
   scrape_interval: ~
   metrics_path: ~

handlers/main.yml

@@ -12,3 +12,8 @@
   service:
     name: prometheus-blackbox-exporter
     state: restarted
+
+- name: restart grafana-promtail
+  service:
+    name: grafana-promtail
+    state: restarted

tasks/main.yml

@@ -56,7 +56,7 @@
       name: certificates
     vars:
       certificates:
-        certs: "{{ {}|combine(prometheus_certs, inventory_certs, recursive=True) }}"
+        certs: "{{ { 'prometheus_agent': ({}|combine(prometheus_certs, inventory_certs, recursive=True))['prometheus_agent'] } }}"
 
 - name: slurp up all scraper certs
   loop: "{{ prometheus_agent.scrapers.keys()|list }}"
@@ -123,6 +123,21 @@
     dest: /etc/prometheus/conf.d/rule_files/agent_{{ inventory_hostname }}.conf
     mode: 0644
 
+- name: handle grafana-promtail
+  when: prometheus_agent.agents.promtail.enable
+  block:
+  - name: install promtail
+    apt:
+      pkg: grafana-promtail
+  - name: wrtie promtail config
+    notify: restart grafana-promtail
+    template:
+      owner: grafana-promtail
+      group: grafana-promtail
+      mode: 0640
+      dest: /etc/grafana-promtail.yml
+      src: grafana-promtail.yml.j2
+
 - name: create node-exporter-textfile group
   ansible.builtin.group:
     name: node-exporter-textfile

templates/grafana-promtail.yml.j2

@@ -0,0 +1,37 @@
+server:
+  disable: true
+  http_listen_port: 9080
+  grpc_listen_port: 0
+
+positions:
+  filename: /var/lib/grafana-promtail/positions.yaml
+
+clients:
+{% for i in prometheus_agent.scrapers if prometheus_agent.scrapers[i].get("loki") %}
+{% set lokiconfig = {}|combine({ "external_labels": merged_prometheus_labels|combine( {"instance": inventory_hostname} ) }, prometheus_agent.scrapers[i]['loki'] ) %}
+  - {{ lokiconfig|to_json }}
+{% endfor %}
+
+scrape_configs:
+- job_name: system
+  static_configs:
+  - targets:
+      - localhost
+    labels:
+      job: varlogs
+      __path__: /var/log/*log
+- job_name: journal
+  journal:
+    max_age: 12h
+    labels:
+      job: systemd-journal
+  relabel_configs:
+    - source_labels: ['__journal__systemd_unit']
+      target_label: 'unit'
+- job_name: nginx
+  static_configs:
+  - targets:
+      - localhost
+    labels:
+      job: nginx
+      __path__: /var/log/nginx/access-promtail.log