[network] normalize instance_name tags

Instance name used to be a part of the check name and hence normalized
on the agent before being sent to Datadog.
As part of changes #1642 which introduced support for custom tags,
'instance_name' is now sent as a proper tag. Normalize it, to avoid mismatch and
backward incompatiblity.

Fix #1796.

checks.d/http_check.py

@@ -72,7 +72,6 @@ def _check(self, instance):
         start = time.time()
 
         service_checks = []
-
         try:
             self.log.debug("Connecting to %s" % addr)
             if disable_ssl_validation and urlparse(addr)[0] == "https":
@@ -240,7 +239,7 @@ def _create_status_event(self, sc_name, status, msg, instance):
         }
 
     def report_as_service_check(self, sc_name, status, instance, msg=None):
-        instance_name = instance['name']
+        instance_name = self.normalize(instance['name'])
         url = instance.get('url', None)
         sc_tags = ['url:{0}'.format(url), "instance:{0}".format(instance_name)]
         custom_tags = instance.get('tags', [])

checks.d/tcp_check.py

@@ -152,7 +152,7 @@ def _create_status_event(self, sc_name, status, msg, instance):
         }
 
     def report_as_service_check(self, sc_name, status, instance, msg=None):
-        instance_name = instance['name']
+        instance_name = self.normalize(instance['name'])
         host = instance.get('host', None)
         port = instance.get('port', None)
         custom_tags = instance.get('tags', [])

checks/__init__.py

@@ -744,7 +744,7 @@ def from_yaml(cls, path_to_yaml=None, agentConfig=None, yaml_text=None, check_na
             check = cls(check_name, config.get('init_config') or {}, agentConfig or {})
         return check, config.get('instances', [])
 
-    def normalize(self, metric, prefix=None, fix_case = False):
+    def normalize(self, metric, prefix=None, fix_case=False):
         """
         Turn a metric into a well-formed metric name
         prefix.b.c