requests integration crashes #396

[2018-11-13 16:05:21,786] ERROR grpc._plugin_wrapping-84 AuthMetadataPluginCallback "<google.auth.transport.grpc.AuthMetadataPlugin object at 0x7fede0585550>" raised exception!
Traceback (most recent call last):
  File "/usr/local/lib/python3.7/site-packages/grpc/_plugin_wrapping.py", line 80, in __call__
    callback_state, callback))
  File "/usr/local/lib/python3.7/site-packages/google/auth/transport/grpc.py", line 77, in __call__
    callback(self._get_authorization_headers(context), None)
  File "/usr/local/lib/python3.7/site-packages/google/auth/transport/grpc.py", line 65, in _get_authorization_headers
    headers)
  File "/usr/local/lib/python3.7/site-packages/google/auth/credentials.py", line 122, in before_request
    self.refresh(request)
  File "/usr/local/lib/python3.7/site-packages/google/auth/compute_engine/credentials.py", line 96, in refresh
    self._retrieve_info(request)
  File "/usr/local/lib/python3.7/site-packages/google/auth/compute_engine/credentials.py", line 78, in _retrieve_info
    service_account=self._service_account_email)
  File "/usr/local/lib/python3.7/site-packages/google/auth/compute_engine/_metadata.py", line 179, in get_service_account_info
    recursive=True)
  File "/usr/local/lib/python3.7/site-packages/google/auth/compute_engine/_metadata.py", line 115, in get
    response = request(url=url, method='GET', headers=_METADATA_HEADERS)
  File "/usr/local/lib/python3.7/site-packages/google/auth/transport/requests.py", line 120, in __call__
    **kwargs)
  File "/usr/local/lib/python3.7/site-packages/opencensus/trace/ext/requests/trace.py", line 115, in wrap_session_request
    tracer_headers = _tracer.propagator.to_headers(
AttributeError: 'NoopTracer' object has no attribute 'propagator'

[2018-11-13 16:05:32,926] ERROR opencensus.trace.ext.django.middleware-259 Failed to trace request
Traceback (most recent call last):
  File "/usr/local/lib/python3.7/site-packages/django/contrib/sessions/backends/base.py", line 190, in _get_session
    return self._session_cache
AttributeError: 'SessionStore' object has no attribute '_session_cache'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/local/lib/python3.7/site-packages/google/api_core/grpc_helpers.py", line 59, in error_remapped_callable
    return callable_(*args, **kwargs)
  File "/usr/local/lib/python3.7/site-packages/grpc/_channel.py", line 533, in __call__
    return _end_unary_response_blocking(state, call, False, None)
  File "/usr/local/lib/python3.7/site-packages/grpc/_channel.py", line 467, in _end_unary_response_blocking
    raise _Rendezvous(state, None, None, deadline)
grpc._channel._Rendezvous: <_Rendezvous of RPC that terminated with:
	status = StatusCode.UNAVAILABLE
	details = "Getting metadata from plugin failed with error: 'NoopTracer' object has no attribute 'propagator'"
	debug_error_string = "{"created":"@1542121532.926029690","description":"Getting metadata from plugin failed with error: 'NoopTracer' object has no attribute 'propagator'","file":"src/core/lib/security/credentials/plugin/plugin_credentials.cc","file_line":82,"grpc_status":14}"
>

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/usr/local/lib/python3.7/site-packages/opencensus/trace/ext/django/middleware.py", line 253, in process_response
    _set_django_attributes(span, request)
  File "/usr/local/lib/python3.7/site-packages/opencensus/trace/ext/django/middleware.py", line 96, in _set_django_attributes
    user_id = django_user.pk
  File "/usr/local/lib/python3.7/site-packages/django/utils/functional.py", line 213, in inner
    self._setup()
  File "/usr/local/lib/python3.7/site-packages/django/utils/functional.py", line 347, in _setup
    self._wrapped = self._setupfunc()
  File "/usr/local/lib/python3.7/site-packages/django/contrib/auth/middleware.py", line 24, in <lambda>
    request.user = SimpleLazyObject(lambda: get_user(request))
  File "/usr/local/lib/python3.7/site-packages/django/contrib/auth/middleware.py", line 12, in get_user
    request._cached_user = auth.get_user(request)
  File "/usr/local/lib/python3.7/site-packages/django/contrib/auth/__init__.py", line 182, in get_user
    user_id = _get_user_session_key(request)
  File "/usr/local/lib/python3.7/site-packages/django/contrib/auth/__init__.py", line 59, in _get_user_session_key
    return get_user_model()._meta.pk.to_python(request.session[SESSION_KEY])
  File "/usr/local/lib/python3.7/site-packages/django/contrib/sessions/backends/base.py", line 55, in __getitem__
    return self._session[key]
  File "/usr/local/lib/python3.7/site-packages/django/contrib/sessions/backends/base.py", line 195, in _get_session
    self._session_cache = self.load()
  File "/usr/local/lib/python3.7/site-packages/django/contrib/sessions/backends/db.py", line 43, in load
    s = self._get_session_from_db()
  File "/usr/local/lib/python3.7/site-packages/django/contrib/sessions/backends/db.py", line 34, in _get_session_from_db
    expire_date__gt=timezone.now()
  File "/usr/local/lib/python3.7/site-packages/django/db/models/manager.py", line 82, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "/usr/local/lib/python3.7/site-packages/django/db/models/query.py", line 393, in get
    num = len(clone)
  File "/usr/local/lib/python3.7/site-packages/django/db/models/query.py", line 250, in __len__
    self._fetch_all()
  File "/usr/local/lib/python3.7/site-packages/django/db/models/query.py", line 1186, in _fetch_all
    self._result_cache = list(self._iterable_class(self))
  File "/usr/local/lib/python3.7/site-packages/django/db/models/query.py", line 54, in __iter__
    results = compiler.execute_sql(chunked_fetch=self.chunked_fetch, chunk_size=self.chunk_size)
  File "/usr/local/lib/python3.7/site-packages/django/db/models/sql/compiler.py", line 1065, in execute_sql
    cursor.execute(sql, params)
  File "/usr/local/lib/python3.7/site-packages/raven/contrib/django/client.py", line 123, in execute
    return real_execute(self, sql, params)
  File "/usr/local/lib/python3.7/site-packages/django/db/backends/utils.py", line 68, in execute
    return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
  File "/usr/local/lib/python3.7/site-packages/django/db/backends/utils.py", line 77, in _execute_with_wrappers
    return executor(sql, params, many, context)
  File "/usr/local/lib/python3.7/site-packages/django/db/backends/utils.py", line 85, in _execute
    return self.cursor.execute(sql, params)
  File "/usr/local/lib/python3.7/site-packages/opencensus/trace/ext/postgresql/trace.py", line 69, in call
    _tracer.end_span()
  File "/usr/local/lib/python3.7/site-packages/opencensus/trace/tracer.py", line 117, in end_span
    self.tracer.end_span()
  File "/usr/local/lib/python3.7/site-packages/opencensus/trace/tracers/context_tracer.py", line 123, in end_span
    self.exporter.export(span_datas)
  File "/usr/local/lib/python3.7/site-packages/opencensus/trace/exporters/stackdriver_exporter.py", line 233, in export
    self.transport.export(span_datas)
  File "/usr/local/lib/python3.7/site-packages/opencensus/trace/exporters/transports/sync.py", line 23, in export
    self.exporter.emit(span_datas)
  File "/usr/local/lib/python3.7/site-packages/opencensus/trace/exporters/stackdriver_exporter.py", line 224, in emit
    self.client.batch_write_spans(project, stackdriver_spans)
  File "/usr/local/lib/python3.7/site-packages/google/cloud/trace/client.py", line 104, in batch_write_spans
    timeout=timeout)
  File "/usr/local/lib/python3.7/site-packages/google/cloud/trace/_gapic.py", line 90, in batch_write_spans
    timeout=timeout)
  File "/usr/local/lib/python3.7/site-packages/google/cloud/trace_v2/gapic/trace_service_client.py", line 200, in batch_write_spans
    request, retry=retry, timeout=timeout, metadata=metadata)
  File "/usr/local/lib/python3.7/site-packages/google/api_core/gapic_v1/method.py", line 139, in __call__
    return wrapped_func(*args, **kwargs)
  File "/usr/local/lib/python3.7/site-packages/google/api_core/grpc_helpers.py", line 61, in error_remapped_callable
    six.raise_from(exceptions.from_grpc_error(exc), exc)
  File "<string>", line 3, in raise_from
google.api_core.exceptions.ServiceUnavailable: 503 Getting metadata from plugin failed with error: 'NoopTracer' object has no attribute 'propagator'