Merge ~hloeung/charm-graylog:master into ~graylog-charmers/charm-graylog:master

[Haw Loeung]

Add nagios checks for both web UI and API

Add basic and simple nagios checks to ensure both Graylog web UI and API services are up.

[Barry Price (barryprice)]

+1

review: Approve

diff --git a/config.yaml b/config.yaml
index f4f86d6..3bc2bd2 100644
--- a/config.yaml
+++ b/config.yaml
@@ -13,3 +13,20 @@ options:
     type: string
     default: "http://0.0.0.0:9000/"
     description: The uri the web interface will be available at.
+  nagios_context:
+    default: "juju"
+    type: string
+    description: |
+      Used by the nrpe-external-master subordinate charm.
+      A string that will be prepended to instance name to set the host name
+      in nagios. So for instance the hostname would be something like:
+          juju-myservice-0
+      If you're running multiple environments with the same services in them
+      this allows you to differentiate between them.
+  nagios_servicegroups:
+    default: ""
+    type: string
+    description: >
+        A comma-separated list of nagios servicegroups.
+        If left empty, the nagios_context will be used as the servicegroup.
+
diff --git a/layer.yaml b/layer.yaml
index 5434c97..3c9b49d 100644
--- a/layer.yaml
+++ b/layer.yaml
@@ -5,6 +5,7 @@ includes:
   - 'interface:elasticsearch'
   - 'interface:http'
   - 'interface:mongodb-cluster'
+  - 'interface:nrpe-external-master'
 options:
   snap:
     graylog:
diff --git a/metadata.yaml b/metadata.yaml
index 03f1516..b5f3096 100644
--- a/metadata.yaml
+++ b/metadata.yaml
@@ -10,6 +10,9 @@ tags:
   - misc
 subordinate: false
 provides:
+  nrpe-external-master:
+    interface: nrpe-external-master
+    scope: container
   website:
     interface: http
 requires:
diff --git a/reactive/graylog.py b/reactive/graylog.py
index 6f2aa95..db7a976 100644
--- a/reactive/graylog.py
+++ b/reactive/graylog.py
@@ -6,6 +6,7 @@ from urllib.parse import urlparse
 from charms.reactive import hook, when, when_not, remove_state, set_state
 from charms.reactive.helpers import data_changed
 from charmhelpers.core import host, hookenv
+from charmhelpers.contrib.charmsupport import nrpe
 
 
 API_PORT = '9001'  # This is the default set by the snap
@@ -144,3 +145,30 @@ def set_conf(key, value, conf_path=CONF_FILE):
 
     with open(conf_path, 'wb') as conf_file:
         conf_file.write('\n'.join(conf).encode())
+
+
+@when('nrpe-external-master.available')
+def configure_nagios(nagios):
+    if hookenv.hook_name() == 'update-status':
+        return
+
+    # Ask charmhelpers.contrib.charmsupport's nrpe to work out our hostname
+    hostname = nrpe.get_nagios_hostname()
+    nrpe_setup = nrpe.NRPE(hostname=hostname, primary=True)
+
+    conf = hookenv.config()
+    if conf['web_listen_uri']:
+        url = urlparse(conf['web_listen_uri'])
+        check_string = '<title>Graylog Web Interface</title>'
+        nrpe_setup.add_check(
+            'graylog_http',
+            'Graylog Web UI check',
+            '/usr/lib/nagios/plugins/check_http -I {} -p {} -s "{}"'.format(url.hostname, str(url.port), check_string)
+        )
+    check_string = 'cluster_id'
+    nrpe_setup.add_check(
+        'graylog_api',
+        'Greylog API check',
+        '/usr/lib/nagios/plugins/check_http -I 127.0.0.1 -p {} -u "/api" -s "{}"'.format(API_PORT, check_string)
+    )
+    nrpe_setup.write()