Fix regex for blackbox exporter targets

Fixes the regex used to match blackbox exporter targets in the
prometheus.yml.j2 template to be less strict. Previously we were using
\w which did not allow for names with periods or hyphens.

Closes-Bug: #2098511
Change-Id: I3ac18bd12ed1dceef206040b3e793faa79717a19

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

@@ -178,17 +178,17 @@ scrape_configs:
 {% endfor %}
     relabel_configs:
       - source_labels: [__address__]
-        regex: (\w+):(\w+):(.+)
+        regex: ([^:]+):([^:]+):(.+)
         target_label: service
         replacement: ${1}
       - source_labels: [__address__]
-        regex: (\w+):(\w+):(.+)
+        regex: ([^:]+):([^:]+):(.+)
         target_label: __param_module
         replacement: ${2}
       - source_labels: [__param_module]
         target_label: module
       - source_labels: [__address__]
-        regex: (\w+):(\w+):(.+)
+        regex: ([^:]+):([^:]+):(.+)
         target_label: __param_target
         replacement: ${3}
       - source_labels: [__param_target]

releasenotes/notes/fix-blackbox-regex-b16f3f86563de6db.yaml

@@ -0,0 +1,7 @@
+---
+fixes:
+  - |
+    Fixes the regex used to match blackbox exporter targets in the
+    ``prometheus.yml.j2`` template to be less strict. Previously we were using
+    ``\w`` which did not allow for names with periods or hyphens. The service
+    and module labels can now contain all characters except for a colon.