[django] add settings to disable django db and cache

Author: mcanaves

ddtrace/contrib/django/__init__.py

@@ -58,6 +58,10 @@
   be useful if you want to use the Django integration, but you want to trace only
   particular functions or views. If set to False, the request middleware will be
   disabled even if present.
+* ``DATABASE_AUTO_INSTRUMENT`` (default: ``True``): if set to false database will not
+ be instrumented. Only is configurable when ``AUTO_INSTRUMENT`` is set to true.
+* ``CACHE_AUTO_INSTRUMENT`` (default: ``True``): if set to false cache will not
+ be instrumented. Only is configurable when ``AUTO_INSTRUMENT`` is set to true.
 * ``AGENT_HOSTNAME`` (default: ``localhost``): define the hostname of the trace agent.
 * ``AGENT_PORT`` (default: ``8126``): define the port of the trace agent.
 """

ddtrace/contrib/django/apps.py

@@ -49,17 +49,20 @@ def ready(self):
         if settings.AUTO_INSTRUMENT:
             # trace Django internals
             insert_exception_middleware()
-            try:
-                patch_db(tracer)
-            except Exception:
-                log.exception('error patching Django database connections')
 
             try:
                 patch_template(tracer)
             except Exception:
                 log.exception('error patching Django template rendering')
 
-            try:
-                patch_cache(tracer)
-            except Exception:
-                log.exception('error patching Django cache')
+            if settings.DATABASE_AUTO_INSTRUMENT:
+                try:
+                    patch_db(tracer)
+                except Exception:
+                    log.exception('error patching Django database connections')
+
+            if settings.CACHE_AUTO_INSTRUMENT:
+                try:
+                    patch_cache(tracer)
+                except Exception:
+                    log.exception('error patching Django cache')

ddtrace/contrib/django/conf.py

@@ -25,6 +25,8 @@
     'AGENT_HOSTNAME': 'localhost',
     'AGENT_PORT': 8126,
     'AUTO_INSTRUMENT': True,
+    'DATABASE_AUTO_INSTRUMENT': True,
+    'CACHE_AUTO_INSTRUMENT': True,
     'DEFAULT_DATABASE_PREFIX': '',
     'DEFAULT_SERVICE': 'django',
     'ENABLED': True,