NEW: authdb option for MongoDB collector (#5707)

* NEW: authdb option for MongoDB collector

* Extended mongodb.conf example with authdb option

* Commented out secure example in mongodb.conf

* FIXED: mongodb changes to be compatible with pre-Py2.4

collectors/python.d.plugin/mongodb/README.md

@@ -156,6 +156,7 @@ Sample:
 ```yaml
 local:
     name : 'local'
+    authdb: 'admin'
     host : '127.0.0.1'
     port : 27017
     user : 'netdata'

collectors/python.d.plugin/mongodb/mongodb.chart.py

@@ -424,6 +424,7 @@ class Service(SimpleService):
         SimpleService.__init__(self, configuration=configuration, name=name)
         self.order = ORDER[:]
         self.definitions = deepcopy(CHARTS)
+        self.authdb = self.configuration.get('authdb', 'admin')
         self.user = self.configuration.get('user')
         self.password = self.configuration.get('pass')
         self.host = self.configuration.get('host', '127.0.0.1')
@@ -707,7 +708,7 @@ class Service(SimpleService):
         try:
             connection = MongoClient(**conn_vars)
             if self.user and self.password:
-                connection.admin.authenticate(name=self.user, password=self.password)
+                getattr(connection, self.authdb).authenticate(name=self.user, password=self.password)
             # elif self.user:
             #     connection.admin.authenticate(name=self.user, mechanism='MONGODB-X509')
             server_status = connection.admin.command('serverStatus')

collectors/python.d.plugin/mongodb/mongodb.conf

@@ -66,6 +66,8 @@
 #
 #  in all cases, the following can also be set:
 #
+#     authdb: 'dbname'       # database to authenticate the user against,
+#                            # defaults to "admin".
 #     user: 'username'       # the mongodb username to use
 #     pass: 'password'       # the mongodb password to use
 #
@@ -80,3 +82,11 @@ local:
     name : 'local'
     host : '127.0.0.1'
     port : 27017
+
+# authsample:
+#     name : 'secure'
+#     host : 'mongodb.example.com'
+#     port : 27017
+#     authdb : 'admin'
+#     user : 'monitor'
+#     password : 'supersecret'