Merge pull request #10 from instana/older_django

Backport Django support to older version 1.9

Author: pglombardo

README.md

@@ -24,10 +24,14 @@ For this BETA, we currently support tracing of Django and Flask applications or
 
 ## Django
 
-To enable the Django instrumentation, set the following environment variable in your _application boot environment_ and then restart your application:
+For Django versions >= 1.10 set the following environment variable in your _application boot environment_ and then restart your application:
 
   `export AUTOWRAPT_BOOTSTRAP=django`
 
+For Django version 1.9.x, instead set:
+
+  `export AUTOWRAPT_BOOTSTRAP=django19`
+
 ## Flask
 
 To enable the Flask instrumentation, set the following environment variable in your _application boot environment_ and then restart your application:

instana/django19.py

@@ -0,0 +1,52 @@
+from __future__ import print_function
+import opentracing as ot
+from instana import tracer, options
+import opentracing.ext.tags as ext
+
+
+DJ19_INSTANA_MIDDLEWARE = 'instana.django19.InstanaMiddleware19'
+
+
+class InstanaMiddleware19(object):
+    """ Django 1.9 Middleware to provide request tracing for Instana """
+    def __init__(self):
+        opts = options.Options(service="Django")
+        ot.global_tracer = tracer.InstanaTracer(opts)
+        self.span = None
+        self
+
+    def process_request(self, request):
+        env = request.environ
+        if 'HTTP_X_INSTANA_T' in env and 'HTTP_X_INSTANA_S' in env:
+            ctx = ot.global_tracer.extract(ot.Format.HTTP_HEADERS, env)
+            span = ot.global_tracer.start_span("django", child_of=ctx)
+        else:
+            span = ot.global_tracer.start_span("django")
+
+        span.set_tag(ext.HTTP_URL, env['PATH_INFO'])
+        span.set_tag("http.params", env['QUERY_STRING'])
+        span.set_tag(ext.HTTP_METHOD, request.method)
+        span.set_tag("http.host", env['HTTP_HOST'])
+        self.span = span
+
+    def process_response(self, request, response):
+        if self.span:
+            self.span.set_tag(ext.HTTP_STATUS_CODE, response.status_code)
+            ot.global_tracer.inject(self.span.context, ot.Format.HTTP_HEADERS, response)
+            self.span.finish()
+            self.span = None
+        return response
+
+
+
+def hook(module):
+    """ Hook method to install the Instana middleware into Django """
+    if DJ19_INSTANA_MIDDLEWARE in module.settings.MIDDLEWARE_CLASSES:
+        return
+
+    if type(module.settings.MIDDLEWARE_CLASSES) is tuple:
+        module.settings.MIDDLEWARE_CLASSES = (DJ19_INSTANA_MIDDLEWARE,) + module.settings.MIDDLEWARE_CLASSES
+    elif type(module.settings.MIDDLEWARE_CLASSES) is list:
+        module.settings.MIDDLEWARE_CLASSES = [DJ19_INSTANA_MIDDLEWARE] + module.settings.MIDDLEWARE_CLASSES
+    else:
+        print("Instana: Couldn't add InstanaMiddleware to Django")

instana/meter.py

@@ -150,6 +150,8 @@ def collect_snapshot(self):
         try:
             if "FLASK_APP" in os.environ:
                 appname = os.environ["FLASK_APP"]
+            elif "DJANGO_SETTINGS_MODULE" in os.environ:
+                appname = os.environ["DJANGO_SETTINGS_MODULE"].split('.')[0]
             else:
                 appname = os.path.basename(sys.executable)
 

instana/propagator.py

@@ -16,7 +16,7 @@ def inject(self, span_context, carrier):
         try:
             trace_id = util.id_to_header(span_context.trace_id)
             span_id = util.id_to_header(span_context.span_id)
-            if type(carrier) is dict:
+            if type(carrier) is dict or hasattr(carrier, "__dict__"):
                 carrier[field_name_trace_id] = trace_id
                 carrier[field_name_span_id] = span_id
             elif type(carrier) is list:
@@ -32,7 +32,7 @@ def inject(self, span_context, carrier):
 
     def extract(self, carrier):  # noqa
         try:
-            if type(carrier) is dict:
+            if type(carrier) is dict or hasattr(carrier, "__dict__"):
                 dc = carrier
             elif type(carrier) is list:
                 dc = dict(carrier)

setup.py

@@ -18,6 +18,7 @@
                         'basictracer>=2.2.0',
                         'psutil>=5.1.3'],
       entry_points={'django': ['django.core.handlers.base = instana.django:hook'],
+                    'django19': ['django.core.handlers.base = instana.django19:hook'],
                     'flask': ['flask.cli = instana.flaskana:hook'],
                     'runtime': ['string = instana.runtime:hook']},
       test_suite='nose.collector',