Merge ~jacekn/prometheus-charm:blackbox-relation into prometheus-charm:master

[Jacek Nykis]

Add blackbox-exporter relation support

diff --git a/config.yaml b/config.yaml
index 0cf42bb..c61f50a 100644
--- a/config.yaml
+++ b/config.yaml
@@ -55,7 +55,8 @@ options:
     description: |
       Can be used to add custom scrape jobs, for example SNMP exporter config.
       This will be parsed as YAML, format is a list of dicts as shown in the example.
-      For convenience "{{ snmp_exporter }}" will be replaced with SNMP exporter address.
+      For convenience "{{ snmp_exporter }}" and "{{ blackbox_exporter }}" will be
+      replaced with SNMP and blackbox exporter addresses respectively.
       Example:
        - job_name: 'snmp'
          scrape_interval: 1m
diff --git a/metadata.yaml b/metadata.yaml
index dc5d651..c06eee2 100644
--- a/metadata.yaml
+++ b/metadata.yaml
@@ -29,6 +29,8 @@ requires:
     interface: http
   snmp-exporter:
     interface: http
+  blackbox-exporter:
+    interface: http
 storage:
   metrics-filesystem:
     type: filesystem
diff --git a/reactive/prometheus.py b/reactive/prometheus.py
index 667158e..e56d5bf 100644
--- a/reactive/prometheus.py
+++ b/reactive/prometheus.py
@@ -276,8 +276,9 @@ def get_manual_jobs():
         return None
     else:
         snmp_exporter = unitdata.kv().get('snmp_exporter_address', '127.0.0.1:9116')
+        blackbox_exporter = unitdata.kv().get('blackbox_exporter_address', '127.0.0.1:9115')
         t = Template(config.get('scrape-jobs'))
-        return t.render(snmp_exporter=snmp_exporter)
+        return t.render(snmp_exporter=snmp_exporter, blackbox_exporter=blackbox_exporter)
 
 
 @when('prometheus.do-reconfig-yml')
@@ -287,7 +288,6 @@ def write_prometheus_config_yml():
 
     ver_major, ver_minor, ver_patch = get_version()
     target_jobs = unitdata.kv().get('target_jobs', [])
-    target_juju_units = unitdata.kv().get('target_juju_units', {})
     scrape_jobs = unitdata.kv().get('scrape_jobs', [])
     manual_jobs = get_manual_jobs()
 
@@ -593,6 +593,13 @@ def update_prometheus_no_snmp_exporter():
 
 
 @when('prometheus.started')
+@when_not('blackbox-exporter.available')
+def update_prometheus_no_blackbox_exporter():
+    unitdata.kv().unset('blackbox_exporter_address')
+    set_state('prometheus.do-check-reconfig')
+
+
+@when('prometheus.started')
 @when('snmp-exporter.available')
 def update_prometheus_snmp_exporter(snmp_exporter):
     services = snmp_exporter.services()
@@ -608,6 +615,21 @@ def update_prometheus_snmp_exporter(snmp_exporter):
 
 
 @when('prometheus.started')
+@when('blackbox-exporter.available')
+def update_prometheus_blackbox_exporter(blackbox_exporter):
+    services = blackbox_exporter.services()
+    if not (data_changed('blackbox-exporter.related_services', services)):
+        return
+    # At this point we only support single blackbox exporter target
+    for service in services:
+        for unit in service['hosts']:
+            hookenv.log('{} has a unit {}:{}'.format(
+                        service['service_name'], unit['hostname'], unit['port']))
+            unitdata.kv().set('blackbox_exporter_address', '{hostname}:{port}'.format(**unit))
+    set_state('prometheus.do-check-reconfig')
+
+
+@when('prometheus.started')
 @when('nrpe-external-master.available')
 def update_nrpe_config(svc):
     hostname = nrpe.get_nagios_hostname()