make "external_labels" optional on prometheus.yml

Closes-bug: 1944699
Change-Id: I6d0bb3b88983846fdd9c8af09456a106a940d191

ansible/roles/prometheus/defaults/main.yml

@@ -109,6 +109,12 @@ prometheus_services:
     volumes: "{{ prometheus_libvirt_exporter_default_volumes + prometheus_libvirt_exporter_extra_volumes }}"
     dimensions: "{{ prometheus_libvirt_exporter_dimensions }}"
 
+####################
+# Prometheus Server
+####################
+prometheus_external_labels:
+#  <labelname>: <labelvalue>
+
 ####################
 # Database
 ####################

ansible/roles/prometheus/templates/prometheus.yml.j2

@@ -2,8 +2,12 @@ global:
   scrape_interval: {{ prometheus_scrape_interval }}
   scrape_timeout: 10s
   evaluation_interval: 15s
+{% if prometheus_external_labels %}
   external_labels:
-    monitor: 'kolla'
+{% for label, value in prometheus_external_labels.items() %}
+    {{ label }}: {{ value }}
+{% endfor %}
+{% endif %}
 
 {% if prometheus_alert_rules.files is defined and prometheus_alert_rules.files | length  > 0 %}
 rule_files:

etc/kolla/globals.yml

@@ -709,6 +709,12 @@ workaround_ansible_issue_8743: yes
 #enable_prometheus_libvirt_exporter: "{{ enable_prometheus | bool and enable_nova | bool and nova_compute_virt_type in ['kvm', 'qemu'] }}"
 #enable_prometheus_etcd_integration: "{{ enable_prometheus | bool and enable_etcd | bool }}"
 
+# The labels to add to any time series or alerts when communicating with external systems (federation, remote storage, Alertmanager).
+# prometheus_external_labels:
+#   <labelname>: <labelvalue>
+# By default, prometheus_external_labels is empty
+#prometheus_external_labels:
+
 # List of extra parameters passed to prometheus. You can add as many to the list.
 #prometheus_cmdline_extras:
 

releasenotes/notes/make-external-labels-optional-744f5454bcfa70f7.yaml

@@ -0,0 +1,8 @@
+---
+fixes:
+  - |
+    Fixes `monitor: kolla` be added in `external_labels` by default.
+    Prometheus default config should not include environment-specific
+    details. In this patch, modify `external_labels` be optional, we
+    can add any `<labelname>: <labelvalue>` in `external_labels`.
+    `LP#1944699 <https://bugs.launchpad.net/kolla-ansible/+bug/1944699>`__