Add support for ssl connections in Mongo check

Fix #848

checks.d/mongo.py

@@ -143,6 +143,12 @@ def check(self, instance):
             return
 
         server = instance['server']
+        use_ssl = instance.get('ssl', None)
+        ssl_keyfile = instance.get('ssl_keyfile', None)
+        ssl_certfile = instance.get('ssl_certfile', None)
+        ssl_cert_reqs = instance.get('ssl_cert_reqs', None)
+        ssl_ca_certs = instance.get('ssl_ca_certs', None)
+
         tags = instance.get('tags', [])
         tags.append('server:%s' % server)
         # de-dupe tags to avoid a memory leak
@@ -178,7 +184,9 @@ def check(self, instance):
             self.log.debug("Mongo: cannot extract username and password from config %s" % server)
             do_auth = False
 
-        conn = Connection(server, network_timeout=DEFAULT_TIMEOUT)
+        conn = Connection(server, network_timeout=DEFAULT_TIMEOUT,
+            ssl=use_ssl, ssl_keyfile=ssl_keyfile, ssl_certfile=ssl_certfile, 
+            ssl_cert_reqs=ssl_cert_reqs, ssl_ca_certs=ssl_ca_certs)
         db = conn[db_name]
         if do_auth:
             if not db.authenticate(username, password):

conf.d/mongo.yaml.example

@@ -4,4 +4,13 @@ instances:
 #   -   server: mongodb://localhost:27017
 #       tags:
 #            - optional_tag1
-#            - optional_tag2
+#            - optional_tag2
+#
+# Optional SSL parameters, see https://github.com/mongodb/mongo-python-driver/blob/2.6.3/pymongo/mongo_client.py#L193-L212 
+# for more details
+#
+#       ssl: False # Optional (default to False)
+#       ssl_keyfile: # Path to the private keyfile used to identify the local
+#       ssl_certfile: # Path to the certificate file used to identify the local connection against mongod.
+#       ssl_cert_reqs: # Specifies whether a certificate is required from the other side of the connection, and whether it will be validated if provided.
+#       ssl_ca_certs: #  Path to the ca_certs file