auto-generate prometheus.yml for workers metrics

docs/configuring-playbook-prometheus-grafana.md

@@ -62,6 +62,34 @@ Name | Description
 
 If you are using workers (`matrix_synapse_workers_enabled`) and have enabled `matrix_nginx_proxy_proxy_synapse_metrics` as described above, the playbook will also automatically proxy the all worker threads's metrics to `https://matrix.DOMAIN/_synapse-worker-TYPE-ID/metrics`, where `TYPE` corresponds to the type and `ID` to the instanceId of a worker as exemplified in `matrix_synapse_workers_enabled_list`.
 
+The playbook also generates an exemplary prometheus.yml config file (`matrix_base_data_path/external_prometheus.yml.template`) with all the correct paths which you can copy to your Prometheus server and adapt to your needs, especially edit the specified `password_file` path and contents and path to your `synapse-v2.rules`.
+It will look a bit like this:
+```yaml
+scrape_configs:
+  - job_name: 'synapse'
+    metrics_path: /_synapse/metrics
+    scheme: https
+    basic_auth:
+      username: prometheus
+      password_file: /etc/prometheus/password.pwd
+    static_configs:
+      - targets: ['matrix.DOMAIN:443']
+        labels:
+          job: "master"
+          index: 1
+  - job_name: 'synapse-generic_worker-1'
+    metrics_path: /_synapse-worker-generic_worker-18111/metrics
+    scheme: https
+    basic_auth:
+      username: prometheus
+      password_file: /etc/prometheus/password.pwd
+    static_configs:
+      - targets: ['matrix.DOMAIN:443']
+        labels:
+          job: "generic_worker"
+          index: 18111
+```
+
 ### Collecting system and Postgres metrics to an external Prometheus server (advanced)
 
 When you normally enable the Prometheus and Grafana via the playbook, it will also show general system (via node-exporter) and Postgres (via postgres-exporter) stats. If you are instead collecting your metrics to an external Prometheus server, you can follow this advanced configuration example to also export these stats.

roles/matrix-nginx-proxy/tasks/setup_nginx_proxy.yml

@@ -38,6 +38,15 @@
     mode: 0400
   when: "matrix_nginx_proxy_proxy_synapse_metrics_basic_auth_enabled|bool and matrix_nginx_proxy_proxy_synapse_metrics|bool"
 
+- name: Generate sample prometheus.yml for external scraping
+  template:
+    src: "{{ role_path }}/templates/prometheus/external_prometheus.yml.example.j2"
+    dest: "{{ matrix_base_data_path }}/external_prometheus.yml.example"
+    owner: "{{ matrix_user_username }}"
+    group: "{{ matrix_user_groupname }}"
+    mode: 0400
+  when: matrix_nginx_proxy_proxy_synapse_metrics|bool
+
 - name: Ensure Matrix nginx-proxy configured (generic)
   template:
     src: "{{ role_path }}/templates/nginx/conf.d/nginx-http.conf.j2"
@@ -270,3 +279,9 @@
     path: "{{ matrix_nginx_proxy_data_path }}/matrix-synapse-metrics-htpasswd"
     state: absent
   when: "not matrix_nginx_proxy_proxy_synapse_metrics_basic_auth_enabled|bool or not matrix_nginx_proxy_proxy_synapse_metrics|bool"
+
+- name: Ensure sample prometheus.yml for external scraping is deleted
+  file:
+    path: "{{ matrix_base_data_path }}/external_prometheus.yml.example"
+    state: absent
+  when: "not matrix_nginx_proxy_proxy_synapse_metrics|bool"

roles/matrix-nginx-proxy/templates/prometheus/external_prometheus.yml.example.j2

@@ -0,0 +1,40 @@
+global:
+  scrape_interval: 5s
+
+  # Attach these labels to any time series or alerts when communicating with
+  # external systems (federation, remote storage, Alertmanager).
+  external_labels:
+    monitor: 'synapse-{{ matrix_domain }}'
+
+rule_files:
+  - /etc/prometheus/synapse-v2.rules
+
+scrape_configs:
+  - job_name: 'synapse'
+    metrics_path: /_synapse/metrics
+    scheme: {{ 'https' if matrix_nginx_proxy_https_enabled else 'http' }}
+{% if matrix_nginx_proxy_proxy_synapse_metrics_basic_auth_enabled %}
+    basic_auth:
+      username: prometheus
+      password_file: /path/to/your/passwordfile.pwd
+{% endif %}
+    static_configs:
+      - targets: ['{{ matrix_server_fqn_matrix }}:{{ matrix_nginx_proxy_container_https_host_bind_port if matrix_nginx_proxy_https_enabled else matrix_nginx_proxy_container_http_host_bind_port }}']
+        labels:
+          job: "master"
+          index: 1
+{% for worker in matrix_nginx_proxy_proxy_synapse_workers_enabled_list %}
+  - job_name: 'synapse-{{ worker.type }}-{{ worker.instanceId }}'
+    metrics_path: /_synapse-worker-{{ worker.type }}-{{ worker.instanceId }}/metrics
+    scheme: {{ 'https' if matrix_nginx_proxy_https_enabled else 'http' }}
+{% if matrix_nginx_proxy_proxy_synapse_metrics_basic_auth_enabled %}
+    basic_auth:
+      username: prometheus
+      password_file: /path/to/your/passwordfile.pwd
+{% endif %}
+    static_configs:
+      - targets: [{{ matrix_server_fqn_matrix }:{{ matrix_nginx_proxy_container_https_host_bind_port if matrix_nginx_proxy_https_enabled else matrix_nginx_proxy_container_http_host_bind_port }}']
+        labels:
+          job: "{{ worker.type }}"
+          index: {{ worker.instanceId }}
+{% endfor %}