Make uniq instance label for remote agent targets

Change-Id: I4297020ebe7316a12dcc017bb786fdf7cd80ed68
Closes-Bug: PROD-25496
diff --git a/prometheus/files/server/prometheus.yml b/prometheus/files/server/prometheus.yml
index 87a6fd0..6722d5f 100644
--- a/prometheus/files/server/prometheus.yml
+++ b/prometheus/files/server/prometheus.yml
@@ -392,4 +392,10 @@
       target_label: environment
       replacement: {{ server.config.environment_label }}
     {%- endif %}
+    {%- if endpoint.name in ['remote_agent', 'remote_agent_openstack'] %}
+    - source_labels: ['__meta_dns_name']
+      regex: ^tasks.(.*)$
+      replacement: $1:{{ endpoint.port }}
+      target_label: 'instance'
+    {%- endif %}
 {%- endfor %}