add nginx proxy connfig for mautrix metrics

roles/custom/matrix-bridge-mautrix-twitter/tasks/inject_into_nginx_proxy.yml

@@ -0,0 +1,33 @@
+---
+
+- name: Fail if matrix-nginx-proxy role already executed
+  ansible.builtin.fail:
+    msg: >-
+      Trying to append mautrix-whatapp-metrics's reverse-proxying configuration to matrix-nginx-proxy,
+      but it's pointless since the matrix-nginx-proxy role had already executed.
+      To fix this, please change the order of roles in your playbook,
+      so that the matrix-nginx-proxy role would run after the matrix-bridge-mautrix-twitter role.
+  when: matrix_nginx_proxy_role_executed | default(False) | bool
+
+- name: Generate mautrix-twitter metrics proxying configuration for matrix-nginx-proxy (matrix.DOMAIN/metrics/mautrix-twitter)
+  ansible.builtin.set_fact:
+    matrix_mautrix_twitter_nginx_metrics_configuration_block: |
+      location /metrics/mautrix-twitter {
+        {% if matrix_nginx_proxy_enabled | default(False) %}
+          {# Use the embedded DNS resolver in Docker containers to discover the service #}
+          resolver 127.0.0.11 valid=5s;
+          set $backend "matrix-mautrix-twitter:8000";
+          proxy_pass http://$backend/metrics;
+        {% else %}
+          return 404 "matrix-nginx-proxy is disabled and no host port was bound to the container, so metrics are unavailable";
+        {% endif %}
+      }
+
+- name: Register mautrix-twitter metrics proxying configuration with matrix-nginx-proxy (matrix.DOMAIN/metrics/mautrix-twitter)
+  ansible.builtin.set_fact:
+    matrix_nginx_proxy_proxy_matrix_metrics_additional_system_location_configuration_blocks: |
+      {{
+        matrix_nginx_proxy_proxy_matrix_metrics_additional_system_location_configuration_blocks | default([])
+        +
+        [matrix_mautrix_twitter_nginx_metrics_configuration_block]
+      }}

roles/custom/matrix-bridge-mautrix-twitter/tasks/main.yml

@@ -1,5 +1,14 @@
 ---
 
+- block:
+    - when: matrix_mautrix_twitter_enabled | bool and matrix_mautrix_twitter_metrics_enabled | bool
+      ansible.builtin.include_tasks: "{{ role_path }}/tasks/inject_into_nginx_proxy.yml"
+  tags:
+    - setup-all
+    - setup-nginx-proxy
+    - install-all
+    - install-nginx-proxy
+
 - block:
     - when: matrix_mautrix_twitter_enabled | bool
       ansible.builtin.include_tasks: "{{ role_path }}/tasks/validate_config.yml"