make instance label optional

bot.py

@@ -27,8 +27,9 @@ TEMPLATE_TEXT = (
     "{% elif labels.severity == 'warning' %}"
     "ATTENTION "
     "{% endif %}"
-    "{{ labels.alertname }} {{ labels.instance }}"
-    "{% if annotations.summary %}"
+    "{{ labels.alertname }}"
+    "{% if labels.instance is defined %} {{ labels.instance }}{% endif %}"
+    "{% if annotations.summary is defined %}"
     "\n{{ annotations.summary }}"
     "{% else %}"
     "{% for key, value in annotations.items() %}"
@@ -45,9 +46,9 @@ TEMPLATE_HTML = (
     "{% elif labels.severity == 'warning' %}"
     "<b><font color='orange'>ATTENTION</font></b> "
     "{% endif %}"
-    "<b>{{ labels.alertname }}</b> "
-    "{{ labels.instance }}"
-    "{% if annotations.summary %}"
+    "<b>{{ labels.alertname }}</b>"
+    "{% if labels.instance is defined %} {{ labels.instance }}{% endif %}"
+    "{% if annotations.summary is defined %}"
     "<br/>"
     "<blockquote>{{ annotations.summary }}</blockquote>"
     "{% else %}"