# Copyright The OpenTelemetry Authors
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""
This library provides a WSGI middleware that can be used on any WSGI framework
(such as Django / Flask) to track requests timing through OpenTelemetry.
Usage (Flask)
-------------
.. code-block:: python
from flask import Flask
from opentelemetry.instrumentation.wsgi import OpenTelemetryMiddleware
app = Flask(__name__)
app.wsgi_app = OpenTelemetryMiddleware(app.wsgi_app)
@app.route("/")
def hello():
return "Hello!"
if __name__ == "__main__":
app.run(debug=True)
Usage (Django)
--------------
Modify the application's ``wsgi.py`` file as shown below.
.. code-block:: python
import os
from opentelemetry.instrumentation.wsgi import OpenTelemetryMiddleware
from django.core.wsgi import get_wsgi_application
os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'application.settings')
application = get_wsgi_application()
application = OpenTelemetryMiddleware(application)
API
---
"""
import functools
import typing
import wsgiref.util as wsgiref_util
from opentelemetry import context, propagators, trace
from opentelemetry.instrumentation.utils import http_status_to_status_code
from opentelemetry.instrumentation.wsgi.version import __version__
from opentelemetry.trace.propagation.textmap import DictGetter
from opentelemetry.trace.status import Status, StatusCode
_HTTP_VERSION_PREFIX = "HTTP/"
[docs]class CarrierGetter(DictGetter):
[docs] def get(self, carrier: dict, key: str) -> typing.List[str]:
"""Getter implementation to retrieve a HTTP header value from the
PEP3333-conforming WSGI environ
Args:
carrier: WSGI environ object
key: header name in environ object
Returns:
A list with a single string with the header value if it exists,
else an empty list.
"""
environ_key = "HTTP_" + key.upper().replace("-", "_")
value = carrier.get(environ_key)
if value is not None:
return [value]
return []
[docs] def keys(self, carrier):
return []
carrier_getter = CarrierGetter()
[docs]def setifnotnone(dic, key, value):
if value is not None:
dic[key] = value
[docs]def collect_request_attributes(environ):
"""Collects HTTP request attributes from the PEP3333-conforming
WSGI environ and returns a dictionary to be used as span creation attributes."""
result = {
"component": "http",
"http.method": environ.get("REQUEST_METHOD"),
"http.server_name": environ.get("SERVER_NAME"),
"http.scheme": environ.get("wsgi.url_scheme"),
}
host_port = environ.get("SERVER_PORT")
if host_port is not None:
result.update({"host.port": int(host_port)})
setifnotnone(result, "http.host", environ.get("HTTP_HOST"))
target = environ.get("RAW_URI")
if target is None: # Note: `"" or None is None`
target = environ.get("REQUEST_URI")
if target is not None:
result["http.target"] = target
else:
result["http.url"] = wsgiref_util.request_uri(environ)
remote_addr = environ.get("REMOTE_ADDR")
if remote_addr:
result["net.peer.ip"] = remote_addr
remote_host = environ.get("REMOTE_HOST")
if remote_host and remote_host != remote_addr:
result["net.peer.name"] = remote_host
user_agent = environ.get("HTTP_USER_AGENT")
if user_agent is not None and len(user_agent) > 0:
result["http.user_agent"] = user_agent
setifnotnone(result, "net.peer.port", environ.get("REMOTE_PORT"))
flavor = environ.get("SERVER_PROTOCOL", "")
if flavor.upper().startswith(_HTTP_VERSION_PREFIX):
flavor = flavor[len(_HTTP_VERSION_PREFIX) :]
if flavor:
result["http.flavor"] = flavor
return result
[docs]def add_response_attributes(
span, start_response_status, response_headers
): # pylint: disable=unused-argument
"""Adds HTTP response attributes to span using the arguments
passed to a PEP3333-conforming start_response callable."""
if not span.is_recording():
return
status_code, status_text = start_response_status.split(" ", 1)
span.set_attribute("http.status_text", status_text)
try:
status_code = int(status_code)
except ValueError:
span.set_status(
Status(
StatusCode.ERROR,
"Non-integer HTTP status: " + repr(status_code),
)
)
else:
span.set_attribute("http.status_code", status_code)
span.set_status(Status(http_status_to_status_code(status_code)))
[docs]def get_default_span_name(environ):
"""Default implementation for name_callback, returns HTTP {METHOD_NAME}."""
return "HTTP {}".format(environ.get("REQUEST_METHOD", "")).strip()
[docs]class OpenTelemetryMiddleware:
"""The WSGI application middleware.
This class is a PEP 3333 conforming WSGI middleware that starts and
annotates spans for any requests it is invoked with.
Args:
wsgi: The WSGI application callable to forward requests to.
name_callback: Callback which calculates a generic span name for an
incoming HTTP request based on the PEP3333 WSGI environ.
Optional: Defaults to get_default_span_name.
"""
def __init__(self, wsgi, name_callback=get_default_span_name):
self.wsgi = wsgi
self.tracer = trace.get_tracer(__name__, __version__)
self.name_callback = name_callback
@staticmethod
def _create_start_response(span, start_response):
@functools.wraps(start_response)
def _start_response(status, response_headers, *args, **kwargs):
add_response_attributes(span, status, response_headers)
return start_response(status, response_headers, *args, **kwargs)
return _start_response
def __call__(self, environ, start_response):
"""The WSGI application
Args:
environ: A WSGI environment.
start_response: The WSGI start_response callable.
"""
token = context.attach(propagators.extract(carrier_getter, environ))
span_name = self.name_callback(environ)
span = self.tracer.start_span(
span_name,
kind=trace.SpanKind.SERVER,
attributes=collect_request_attributes(environ),
)
try:
with self.tracer.use_span(span):
start_response = self._create_start_response(
span, start_response
)
iterable = self.wsgi(environ, start_response)
return _end_span_after_iterating(
iterable, span, self.tracer, token
)
except Exception as ex:
if span.is_recording():
span.set_status(Status(StatusCode.ERROR, str(ex)))
span.end()
context.detach(token)
raise
# Put this in a subfunction to not delay the call to the wrapped
# WSGI application (instrumentation should change the application
# behavior as little as possible).
def _end_span_after_iterating(iterable, span, tracer, token):
try:
with tracer.use_span(span):
for yielded in iterable:
yield yielded
finally:
close = getattr(iterable, "close", None)
if close:
close()
span.end()
context.detach(token)