add prometheus manual targets relation

config.yaml

@@ -1,4 +1,9 @@
 "options":
+  "job-name":
+    "type": "string"
+    "default": !!str "node-exporter"
+    "description": |
+      Default job name passed to prometheus scrape config
   "host":
     "type": "string"
     "default": !!str "0.0.0.0"

layer.yaml

@@ -8,5 +8,6 @@
 "includes":
 - "layer:basic"
 - "interface:prometheus"
+- "interface:prometheus-manual"
 "repo": "https://github.com/CanonicalLtd/prometheus-node-exporter-charm"
 "is": "prometheus-node-exporter"

metadata.yaml

@@ -14,6 +14,10 @@
     "interface": "juju-info"
     "scope": "container"
 "provides":
+  "prometheus-manual-job":
+    "interface": "prometheus-manual"
+  "prometheus-target":
+    "interface": "http"
   "scrape":
     "interface": "prometheus"
 "resources":

reactive/prometheus_node_exporter.py

@@ -1,4 +1,5 @@
 import os
+import socket
 from shutil import copyfile
 from subprocess import call
 
@@ -162,6 +163,50 @@ def prometheus_left():
     clear_flag('prometheus.node.exporter.configured_port')
 
 
+@when('prometheus-target.available')
+def configure_http(prometheus_target):
+    job_name = 'node-exporter'
+    log('Register target {}: {}:{}'.format(
+        job_name,
+        get_ip()[1],
+        config.get('port')
+    ))
+    open_port(config.get('port'))
+    prometheus_target.configure(
+        private_address=get_ip()[1],
+        port=config('port')
+    )
+
+
+@when('endpoint.prometheus-manual-job.joined')
+def register_prometheus_jobs():
+    prometheus = endpoint_from_flag('endpoint.prometheus-manual-job.joined')
+    job_name = config('job-name')
+    target = '{}:{}'.format(
+        get_ip()[1],
+        config('port')
+    )
+    labels = {}
+    try:
+        labels['fqdn'] = socket.getfqdn()
+    except Exception as e:
+        log('Failed to read FQDN: {}'.format(str(e)))
+    try:
+        labels['hostname'] = socket.gethostname()
+    except Exception as e:
+        log('Failed to read FQDN: {}'.format(str(e)))
+    log('Register manual-job {}: {}'.format(job_name, target))
+    open_port(config('port'))
+    prometheus.register_job(
+        job_name=job_name,
+        job_data={
+            'static_configs': [{
+                'targets': [target],
+                'labels': labels
+            }]
+        })
+
+
 @hook('stop')
 def cleanup():
     status_set("maintenance", "cleaning up prometheus-node-exporter")
@@ -170,3 +215,16 @@ def cleanup():
     for f in [NODE_EXPORTER_BIN, NODE_EXPORTER_SERVICE]:
         call('rm {}'.format(f).split())
     status_set("active", "cleanup complete")
+
+
+def get_ip():
+    """Get internal IP and relation IP"""
+    rel_ip = None
+    main_ip = unit_private_ip() if (
+        not config('host') or (config('host') == "none")
+    ) else config('host')
+    if not main_ip or (main_ip == '0.0.0.0'):
+        rel_ip = unit_private_ip()
+    if not rel_ip:
+        rel_ip = main_ip
+    return main_ip, rel_ip