Add support for regular expression matching and sanitizing of headers…

… in ASGI. (#1333)
open-telemetry · Oct 24, 2022 · 9d6ba63 · 9d6ba63
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -6,24 +6,31 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased](https://github.com/open-telemetry/opentelemetry-python/compare/v1.13.0-0.34b0...HEAD)
-- Add metric instrumentation for tornado
-  ([#1252](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/1252))
-- Fix bug in Falcon instrumentation
-  ([#1377](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/1377))
 
 
 ### Added
 
+- Add metric instrumentation for tornado
+  ([#1252](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/1252))
 - `opentelemetry-instrumentation-django` Fixed bug where auto-instrumentation fails when django is installed and settings are not configured.
   ([#1369](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/1369))
 - `opentelemetry-instrumentation-system-metrics` add supports to collect system thread count. ([#1339](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/1339))
 - `opentelemetry-exporter-richconsole` Fixing RichConsoleExpoter to allow multiple traces, fixing duplicate spans and include resources ([#1336](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/1336))
+- `opentelemetry-instrumentation-asgi` Add support for regular expression matching of HTTP headers.
+  ([#1333](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/1333))
 - `opentelemetry-instrumentation-asgi` metrics record target attribute (FastAPI only)
   ([#1323](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/1323))
 
-## [1.13.0-0.34b0](https://github.com/open-telemetry/opentelemetry-python/releases/tag/v1.13.0-0.34b0) - 2022-09-26
+### Fixed
 
+- Fix bug in Falcon instrumentation
+  ([#1377](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/1377))
+- `opentelemetry-instrumentation-asgi` Fix keys() in class ASGIGetter so it decodes the keys before returning them.
+  ([#1333](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/1333))
+- `opentelemetry-instrumentation-asgi` Make ASGIGetter.get() compare all keys in a case insensitive manner.
+  ([#1333](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/1333))
 
+## [1.13.0-0.34b0](https://github.com/open-telemetry/opentelemetry-python/releases/tag/v1.13.0-0.34b0) - 2022-09-26
 
 - `opentelemetry-instrumentation-asyncpg` Fix high cardinality in the span name
   ([#1324](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/1324))
@@ -44,7 +51,6 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Add metric instrumentation in starlette
   ([#1327](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/1327))
 
-
 ### Fixed
 
 - `opentelemetry-instrumentation-boto3sqs` Make propagation compatible with other SQS instrumentations, add 'messaging.url' span attribute, and fix missing package dependencies.

diff --git a/...ion/opentelemetry-instrumentation-asgi/src/opentelemetry/instrumentation/asgi/__init__.py b/...ion/opentelemetry-instrumentation-asgi/src/opentelemetry/instrumentation/asgi/__init__.py
@@ -15,8 +15,7 @@
 
 """
 The opentelemetry-instrumentation-asgi package provides an ASGI middleware that can be used
-on any ASGI framework (such as Django-channels / Quart) to track requests
-timing through OpenTelemetry.
+on any ASGI framework (such as Django-channels / Quart) to track request timing through OpenTelemetry.
 
 Usage (Quart)
 -------------
@@ -71,9 +70,14 @@ async def hello():
 Request/Response hooks
 **********************
 
-Utilize request/response hooks to execute custom logic to be performed before/after performing a request. The server request hook takes in a server span and ASGI
-scope object for every incoming request. The client request hook is called with the internal span and an ASGI scope which is sent as a dictionary for when the method receive is called.
-The client response hook is called with the internal span and an ASGI event which is sent as a dictionary for when the method send is called.
+This instrumentation supports request and response hooks. These are functions that get called
+right after a span is created for a request and right before the span is finished for the response.
+
+- The server request hook is passed a server span and ASGI scope object for every incoming request.
+- The client request hook is called with the internal span and an ASGI scope when the method ``receive`` is called.
+- The client response hook is called with the internal span and an ASGI event when the method ``send`` is called.
+
+For example,
 
 .. code-block:: python
 
@@ -93,54 +97,93 @@ def client_response_hook(span: Span, message: dict):
 
 Capture HTTP request and response headers
 *****************************************
-You can configure the agent to capture predefined HTTP headers as span attributes, according to the `semantic convention <https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/trace/semantic_conventions/http.md#http-request-and-response-headers>`_.
+You can configure the agent to capture specified HTTP headers as span attributes, according to the
+`semantic convention <https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/trace/semantic_conventions/http.md#http-request-and-response-headers>`_.
 
 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.
+To capture HTTP request headers as span attributes, set the environment variable
+``OTEL_INSTRUMENTATION_HTTP_CAPTURE_HEADERS_SERVER_REQUEST`` to a comma delimited 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.
+will extract ``content-type`` and ``custom_request_header`` from the request headers and add them as span attributes.
+
+Request header names in ASGI are case-insensitive. So, giving the header name as ``CUStom-Header`` in the environment
+variable will capture the header named ``custom-header``.
+
+Regular expressions may also be used to match multiple headers that correspond to the given pattern.  For example:
+::
+
+    export OTEL_INSTRUMENTATION_HTTP_CAPTURE_HEADERS_SERVER_REQUEST="Accept.*,X-.*"
 
-It is recommended that you should give the correct names of the headers to be captured in the environment variable.
-Request header names in ASGI are case insensitive. So, giving header name as ``CUStom-Header`` in environment variable will be able capture header with name ``custom-header``.
+Would match all request headers that start with ``Accept`` and ``X-``.
 
-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.
+To capture all request headers, set ``OTEL_INSTRUMENTATION_HTTP_CAPTURE_HEADERS_SERVER_REQUEST`` to ``".*"``.
+::
+
+    export OTEL_INSTRUMENTATION_HTTP_CAPTURE_HEADERS_SERVER_REQUEST=".*"
 
-Example of the added span attribute,
+The name of the added span attribute will follow the format ``http.request.header.<header_name>`` where ``<header_name>``
+is the normalized HTTP header name (lowercase, with ``-`` replaced by ``_``). The value of the attribute will be a
+single item list containing all the header values.
+
+For example:
 ``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.
+To capture HTTP response headers as span attributes, set the environment variable
+``OTEL_INSTRUMENTATION_HTTP_CAPTURE_HEADERS_SERVER_RESPONSE`` to a comma delimited 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.
+will extract ``content-type`` and ``custom_response_header`` from the response headers and add them as span attributes.
+
+Response header names in ASGI are case-insensitive. So, giving the header name as ``CUStom-Header`` in the environment
+variable will capture the header named ``custom-header``.
+
+Regular expressions may also be used to match multiple headers that correspond to the given pattern.  For example:
+::
+
+    export OTEL_INSTRUMENTATION_HTTP_CAPTURE_HEADERS_SERVER_RESPONSE="Content.*,X-.*"
 
-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 ASGI are case insensitive. So, giving header name as ``CUStomHeader`` in environment variable will be able capture header with name ``customheader``.
+Would match all response headers that start with ``Content`` and ``X-``.
 
-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.
+To capture all response headers, set ``OTEL_INSTRUMENTATION_HTTP_CAPTURE_HEADERS_SERVER_RESPONSE`` to ``".*"``.
+::
+
+    export OTEL_INSTRUMENTATION_HTTP_CAPTURE_HEADERS_SERVER_RESPONSE=".*"
 
-Example of the added span attribute,
+The name of the added span attribute will follow the format ``http.response.header.<header_name>`` where ``<header_name>``
+is the normalized HTTP header name (lowercase, with ``-`` replaced by ``_``). The value of the attribute will be a
+single item list containing all the header values.
+
+For example:
 ``http.response.header.custom_response_header = ["<value1>,<value2>"]``
 
+Sanitizing headers
+******************
+In order to prevent storing sensitive data such as personally identifiable information (PII), session keys, passwords,
+etc, set the environment variable ``OTEL_INSTRUMENTATION_HTTP_CAPTURE_HEADERS_SANITIZE_FIELDS``
+to a comma delimited list of HTTP header names to be sanitized.  Regexes may be used, and all header names will be
+matched in a case-insensitive manner.
+
+For example,
+::
+
+    export OTEL_INSTRUMENTATION_HTTP_CAPTURE_HEADERS_SANITIZE_FIELDS=".*session.*,set-cookie"
+
+will replace the value of headers such as ``session-id`` and ``set-cookie`` with ``[REDACTED]`` in the span.
+
 Note:
-    Environment variable names to capture http headers are still experimental, and thus are subject to change.
+    The environment variable names used to capture HTTP headers are still experimental, and thus are subject to change.
 
 API
 ---
@@ -170,8 +213,10 @@ def client_response_hook(span: Span, message: dict):
 from opentelemetry.trace import Span, set_span_in_context
 from opentelemetry.trace.status import Status, StatusCode
 from opentelemetry.util.http import (
+    OTEL_INSTRUMENTATION_HTTP_CAPTURE_HEADERS_SANITIZE_FIELDS,
     OTEL_INSTRUMENTATION_HTTP_CAPTURE_HEADERS_SERVER_REQUEST,
     OTEL_INSTRUMENTATION_HTTP_CAPTURE_HEADERS_SERVER_RESPONSE,
+    SanitizeValue,
     _parse_active_request_count_attrs,
     _parse_duration_attrs,
     get_custom_headers,
@@ -203,19 +248,19 @@ def get(
         if not headers:
             return None
 
-        # asgi header keys are in lower case
+        # ASGI header keys are in lower case
         key = key.lower()
         decoded = [
             _value.decode("utf8")
             for (_key, _value) in headers
-            if _key.decode("utf8") == key
+            if _key.decode("utf8").lower() == key
         ]
         if not decoded:
             return None
         return decoded
 
     def keys(self, carrier: dict) -> typing.List[str]:
-        return list(carrier.keys())
+        return [_key.decode("utf8") for (_key, _value) in carrier]
 
 
 asgi_getter = ASGIGetter()
@@ -290,35 +335,50 @@ def collect_custom_request_headers_attributes(scope):
     """returns custom HTTP request headers to be added into SERVER span as span attributes
     Refer specification https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/trace/semantic_conventions/http.md#http-request-and-response-headers"""
 
-    attributes = {}
-    custom_request_headers = get_custom_headers(
-        OTEL_INSTRUMENTATION_HTTP_CAPTURE_HEADERS_SERVER_REQUEST
+    sanitize = SanitizeValue(
+        get_custom_headers(
+            OTEL_INSTRUMENTATION_HTTP_CAPTURE_HEADERS_SANITIZE_FIELDS
+        )
     )
 
-    for header in custom_request_headers:
-        values = asgi_getter.get(scope, header)
-        if values:
-            key = normalise_request_header_name(header)
-            attributes.setdefault(key, []).extend(values)
+    # Decode headers before processing.
+    headers = {
+        _key.decode("utf8"): _value.decode("utf8")
+        for (_key, _value) in scope.get("headers")
+    }
 
-    return attributes
+    return sanitize.sanitize_header_values(
+        headers,
+        get_custom_headers(
+            OTEL_INSTRUMENTATION_HTTP_CAPTURE_HEADERS_SERVER_REQUEST
+        ),
+        normalise_request_header_name,
+    )
 
 
 def collect_custom_response_headers_attributes(message):
     """returns custom HTTP response headers to be added into SERVER span as span attributes
     Refer specification https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/trace/semantic_conventions/http.md#http-request-and-response-headers"""
-    attributes = {}
-    custom_response_headers = get_custom_headers(
-        OTEL_INSTRUMENTATION_HTTP_CAPTURE_HEADERS_SERVER_RESPONSE
+
+    sanitize = SanitizeValue(
+        get_custom_headers(
+            OTEL_INSTRUMENTATION_HTTP_CAPTURE_HEADERS_SANITIZE_FIELDS
+        )
     )
 
-    for header in custom_response_headers:
-        values = asgi_getter.get(message, header)
-        if values:
-            key = normalise_response_header_name(header)
-            attributes.setdefault(key, []).extend(values)
+    # Decode headers before processing.
+    headers = {
+        _key.decode("utf8"): _value.decode("utf8")
+        for (_key, _value) in message.get("headers")
+    }
 
-    return attributes
+    return sanitize.sanitize_header_values(
+        headers,
+        get_custom_headers(
+            OTEL_INSTRUMENTATION_HTTP_CAPTURE_HEADERS_SERVER_RESPONSE
+        ),
+        normalise_response_header_name,
+    )
 
 
 def get_host_port_url_tuple(scope):
@@ -354,7 +414,7 @@ def set_status_code(span, status_code):
 def get_default_span_details(scope: dict) -> Tuple[str, dict]:
     """Default implementation for get_default_span_details
     Args:
-        scope: the asgi scope dictionary
+        scope: the ASGI scope dictionary
     Returns:
         a tuple of the span name, and any attributes to attach to the span.
     """
@@ -455,7 +515,7 @@ async def __call__(self, scope, receive, send):
         """The ASGI application
 
         Args:
-            scope: A ASGI environment.
+            scope: An ASGI environment.
             receive: An awaitable callable yielding dictionaries
             send: An awaitable callable taking a single dictionary as argument.
         """