OpenTelemetry WSGI Instrumentation

This library provides a WSGI middleware that can be used on any WSGI framework (such as Django / Flask / Web.py) to track requests timing through OpenTelemetry.

Usage (Flask)

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.

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)

Usage (Web.py)

import web
from opentelemetry.instrumentation.wsgi import OpenTelemetryMiddleware
from cheroot import wsgi

urls = ('/', 'index')


class index:

    def GET(self):
        return "Hello, world!"


if __name__ == "__main__":
    app = web.application(urls, globals())
    func = app.wsgifunc()

    func = OpenTelemetryMiddleware(func)

    server = wsgi.WSGIServer(
        ("localhost", 5100), func, server_name="localhost"
    )
    server.start()

Configuration

Request/Response hooks

Utilize request/reponse hooks to execute custom logic to be performed before/after performing a request. Environ is an instance of WSGIEnvironment. Response_headers is a list of key-value (tuples) representing the response headers returned from the response.

def request_hook(span: Span, environ: WSGIEnvironment):
    if span and span.is_recording():
        span.set_attribute("custom_user_attribute_from_request_hook", "some-value")

def response_hook(span: Span, environ: WSGIEnvironment, status: str, response_headers: List):
    if span and span.is_recording():
        span.set_attribute("custom_user_attribute_from_response_hook", "some-value")

OpenTelemetryMiddleware(request_hook=request_hook, response_hook=response_hook)

Capture HTTP request and response headers

You can configure the agent to capture predefined HTTP headers as span attributes, according to the semantic convention.

Request headers

To capture predefined HTTP request headers as span attributes, set the environment variable OTEL_INSTRUMENTATION_HTTP_CAPTURE_HEADERS_SERVER_REQUEST to a comma-separated list of HTTP header names.

For example,

export OTEL_INSTRUMENTATION_HTTP_CAPTURE_HEADERS_SERVER_REQUEST="content-type,custom_request_header"

will extract content-type and custom_request_header from request headers and add them as span attributes.

It is recommended that you should give the correct names of the headers to be captured in the environment variable. Request header names in wsgi are case insensitive and - characters are replaced by _. So, giving header name as CUStom_Header in environment variable will be able capture header with name custom-header.

The name of the added span attribute will follow the format http.request.header.<header_name> where <header_name> being the normalized HTTP header name (lowercase, with - characters replaced by _ ). The value of the attribute will be single item list containing all the header values.

Example of the added span attribute, http.request.header.custom_request_header = ["<value1>,<value2>"]

Response headers

To capture predefined HTTP response headers as span attributes, set the environment variable OTEL_INSTRUMENTATION_HTTP_CAPTURE_HEADERS_SERVER_RESPONSE to a comma-separated list of HTTP header names.

For example,

export OTEL_INSTRUMENTATION_HTTP_CAPTURE_HEADERS_SERVER_RESPONSE="content-type,custom_response_header"

will extract content-type and custom_response_header from response headers and add them as span attributes.

It is recommended that you should give the correct names of the headers to be captured in the environment variable. Response header names captured in wsgi are case insensitive. So, giving header name as CUStomHeader in environment variable will be able capture header with name customheader.

The name of the added span attribute will follow the format http.response.header.<header_name> where <header_name> being the normalized HTTP header name (lowercase, with - characters replaced by _ ). The value of the attribute will be single item list containing all the header values.

Example of the added span attribute, http.response.header.custom_response_header = ["<value1>,<value2>"]

Note

Environment variable names to capture http headers are still experimental, and thus are subject to change.

API

class opentelemetry.instrumentation.wsgi.WSGIGetter(*args, **kwds)[source]

Bases: opentelemetry.propagators.textmap.Getter[dict]

get(carrier, key)[source]
Getter implementation to retrieve a HTTP header value from the

PEP3333-conforming WSGI environ

Parameters
  • carrier (dict) – WSGI environ object

  • key (str) –

    header name in environ object

    Returns:

    A list with a single string with the header value if it exists, else None.

Return type

Optional[List[str]]

keys(carrier)[source]

Function that can retrieve all the keys in a carrier object.

Parameters

carrier – An object which contains values that are used to construct a Context.

Returns

list of keys from the carrier.

opentelemetry.instrumentation.wsgi.setifnotnone(dic, key, value)[source]
opentelemetry.instrumentation.wsgi.collect_request_attributes(environ)[source]

Collects HTTP request attributes from the PEP3333-conforming WSGI environ and returns a dictionary to be used as span creation attributes.

opentelemetry.instrumentation.wsgi.collect_custom_request_headers_attributes(environ)[source]

Returns custom HTTP request headers which are configured by the user from the PEP3333-conforming WSGI environ to be used as span creation attributes as described in the specification https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/trace/semantic_conventions/http.md#http-request-and-response-headers

opentelemetry.instrumentation.wsgi.collect_custom_response_headers_attributes(response_headers)[source]

Returns custom HTTP response headers which are configured by the user from the PEP3333-conforming WSGI environ as described in the specification https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/trace/semantic_conventions/http.md#http-request-and-response-headers

opentelemetry.instrumentation.wsgi.add_response_attributes(span, start_response_status, response_headers)[source]

Adds HTTP response attributes to span using the arguments passed to a PEP3333-conforming start_response callable.

opentelemetry.instrumentation.wsgi.get_default_span_name(environ)[source]

Default implementation for name_callback, returns HTTP {METHOD_NAME}.

class opentelemetry.instrumentation.wsgi.OpenTelemetryMiddleware(wsgi, request_hook=None, response_hook=None, tracer_provider=None, meter_provider=None)[source]

Bases: object

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.

Parameters
  • wsgi – The WSGI application callable to forward requests to.

  • request_hook – Optional callback which is called with the server span and WSGI environ object for every incoming request.

  • response_hook – Optional callback which is called with the server span, WSGI environ, status_code and response_headers for every incoming request.

  • tracer_provider – Optional tracer provider to use. If omitted the current globally configured one is used.

class opentelemetry.instrumentation.wsgi.ResponsePropagationSetter[source]

Bases: object

set(carrier, key, value)[source]