make them show as jobs in grafana

roles/matrix-prometheus/templates/prometheus.yml.j2

@@ -30,13 +30,18 @@ scrape_configs:
   - job_name: 'synapse'
     metrics_path: '/_synapse/metrics'
     static_configs:
-    - targets:
-    {% for target in matrix_prometheus_scraper_synapse_targets %}
-      - {{ target }}
-    {% endfor %}
+    - targets: {{ matrix_prometheus_scraper_synapse_targets|to_json }}
+      labels:
+        instance: {{ matrix_domain }}
+        job: master
+        index: 1
   {% for worker in matrix_synapse_workers_enabled_list|d([]) %}
   {% if worker.metrics_port != 0 %}
-      - 'matrix-synapse-worker-{{ worker.type }}-{{ worker.instanceId }}:{{ worker.metrics_port }}'
+    - targets: ['matrix-synapse-worker-{{ worker.type }}-{{ worker.instanceId }}:{{ worker.metrics_port }}']
+      labels:
+        instance: {{ matrix_domain }}
+        job: {{ worker.type }}
+        index: {{ worker.instanceId }}
   {% endif %}
   {% endfor %}
   {% endif %}