Merge ~ballot/charm-telegraf/+git/telegraf-charm:add_relations into ~telegraf-charmers/charm-telegraf:master

[Benjamin Allot]

Unmerged commits

5788930... by Benjamin Allot on 2019-10-02

Add input-prometheus interface

diff --git a/layer.yaml b/layer.yaml
index 7c1b2bd..15fe2fc 100644
--- a/layer.yaml
+++ b/layer.yaml
@@ -30,6 +30,7 @@ includes:
     - interface:prometheus-rules
     - interface:rabbitmq
     - interface:redis
+    - interface:input-prometheus
 options:
     basic:
         use_venv: true
diff --git a/metadata.yaml b/metadata.yaml
index bf43b34..900f0f5 100644
--- a/metadata.yaml
+++ b/metadata.yaml
@@ -72,6 +72,9 @@ requires:
   sentry:
     interface: sentry-metrics
     scope: container
+  input-prometheus: 
+    interface: input-prometheus
+    scope: container
 provides:
   prometheus-client:
     interface: http
diff --git a/reactive/telegraf.py b/reactive/telegraf.py
index 4ad854c..1ef46f2 100644
--- a/reactive/telegraf.py
+++ b/reactive/telegraf.py
@@ -969,3 +969,44 @@ def update_status():
         hash_type='sha256')
     if changed:
         clear_flag('telegraf.configured')
+
+
+@when('input-prometheus.available')
+def input_prometheus(urls):
+    """Add a relation for prometheus input.
+
+    Allow telefraf to scrape a list of urls in prometheus format.
+    """
+    template = """
+[[inputs.internal]]
+
+[[inputs.prometheus]]
+  urls = {{ urls }}
+"""
+    config_path = '{0}/{1}.conf'.format(get_configs_dir(), 'input-prometheus')
+    rels = hookenv.relations_of_type('input-prometheus')
+    prom_urls = []
+    for rel in rels:
+        enabled = rel.get('enabled', False)
+        # Juju gives us a string instead of a boolean, fix it
+        if isinstance(enabled, str):
+            if enabled in ['y', 'yes', 'true', 't', 'on', 'True']:
+                enabled = True
+            else:
+                enabled = False
+        if not enabled:
+            continue
+        addr = rel['private-address']
+        if addr == hookenv.unit_private_ip():
+            addr = "localhost"
+        port = rel['port']
+        prom_url = 'http://{0}:{1}/metrics'.format(addr, port)
+        prom_urls.append(prom_url)
+    if prom_urls:
+        input_config = render_template(template, {"urls": json.dumps(prom_urls)})
+        hookenv.log("Updating {0} plugin config file".format('input-prometheus'))
+        host.write_file(config_path, input_config.encode('utf-8'))
+        set_flag('plugins.input-prometheus.configured')
+    elif os.path.exists(config_path):
+        os.unlink(config_path)
+    set_flag('telegraf.needs_reload')