Repository: open-telemetry/opentelemetry-python-contrib

Issue:
Add more features for adding HTTP request / response headers to spans.
I already have https://github.com/open-telemetry/opentelemetry-python-contrib/pull/1172 open for this, and I'll be breaking it in to smaller pieces at @lzchen 's request.

**Is your feature request related to a problem?**
Currently, you can only provide a list of full HTTP request / response header names to be added to the span.

There is also no capacity for header value redaction.

**Describe the solution you'd like**
It would be nice to be able to specify a regex or "all" to get all headers.

Header value redaction is also a must-have for us.

**Describe alternatives you've considered**
I considered doing this in my application, but it makes more sense to add it here.



Discussion:

Resolving patch:
diff --git a/instrumentation/opentelemetry-instrumentation-django/src/opentelemetry/instrumentation/django/__init__.py b/instrumentation/opentelemetry-instrumentation-django/src/opentelemetry/instrumentation/django/__init__.py
--- a/instrumentation/opentelemetry-instrumentation-django/src/opentelemetry/instrumentation/django/__init__.py
+++ b/instrumentation/opentelemetry-instrumentation-django/src/opentelemetry/instrumentation/django/__init__.py
@@ -94,8 +94,9 @@
 
 Exclude lists
 *************
-To exclude certain URLs from being tracked, set the environment variable ``OTEL_PYTHON_DJANGO_EXCLUDED_URLS``
-(or ``OTEL_PYTHON_EXCLUDED_URLS`` as fallback) with comma delimited regexes representing which URLs to exclude.
+To exclude certain URLs from tracking, set the environment variable ``OTEL_PYTHON_DJANGO_EXCLUDED_URLS``
+(or ``OTEL_PYTHON_EXCLUDED_URLS`` to cover all instrumentations) to a string of comma delimited regexes that match the
+URLs.
 
 For example,
 
@@ -107,8 +108,8 @@
 
 Request attributes
 ********************
-To extract certain attributes from Django's request object and use them as span attributes, set the environment variable ``OTEL_PYTHON_DJANGO_TRACED_REQUEST_ATTRS`` to a comma
-delimited list of request attribute names.
+To extract attributes from Django's request object and use them as span attributes, set the environment variable
+``OTEL_PYTHON_DJANGO_TRACED_REQUEST_ATTRS`` to a comma delimited list of request attribute names.
 
 For example,
 
@@ -116,14 +117,15 @@
 
     export OTEL_PYTHON_DJANGO_TRACED_REQUEST_ATTRS='path_info,content_type'
 
-will extract path_info and content_type attributes from every traced request and add them as span attritbues.
+will extract the ``path_info`` and ``content_type`` attributes from every traced request and add them as span attributes.
 
 Django Request object reference: https://docs.djangoproject.com/en/3.1/ref/request-response/#attributes
 
 Request and Response hooks
 ***************************
-The instrumentation supports specifying request and response hooks. These are functions that get called back by the instrumentation right after a Span is created for a request
-and right before the span is finished while processing a response. The hooks can be configured as follows:
+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 hooks can be configured as follows:
 
 .. code:: python
 
@@ -140,50 +142,94 @@ def response_hook(span, request, response):
 
 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"
+    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.
 
-It is recommended that you should give the correct names of the headers to be captured in the environment variable.
-Request header names in django are case insensitive. So, giving header name as ``CUStom_Header`` in environment variable will be able capture header with name ``custom-header``.
+Request header names in Django are case-insensitive. So, giving the header name as ``CUStom-Header`` in the environment
+variable will capture the header named ``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.
+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-.*"
+
+Would match all request headers that start with ``Accept`` and ``X-``.
+
+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"
+    export OTEL_INSTRUMENTATION_HTTP_CAPTURE_HEADERS_SERVER_RESPONSE="content-type,custom_response_header"
+
+will extract ``content-type`` and ``custom_response_header`` from the response headers and add them as span attributes.
 
-will extract content_type and custom_response_header from response headers and add them as span attributes.
+Response header names in Django are case-insensitive. So, giving the header name as ``CUStom-Header`` in the environment
+variable will capture the header named ``custom-header``.
 
-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 django are case insensitive. So, giving header name as ``CUStomHeader`` in environment variable will be able capture header with name ``customheader``.
+Regular expressions may also be used to match multiple headers that correspond to the given pattern.  For example:
+::
 
-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.
+    export OTEL_INSTRUMENTATION_HTTP_CAPTURE_HEADERS_SERVER_RESPONSE="Content.*,X-.*"
 
-Example of the added span attribute,
+Would match all response headers that start with ``Content`` and ``X-``.
+
+To capture all response headers, set ``OTEL_INSTRUMENTATION_HTTP_CAPTURE_HEADERS_SERVER_RESPONSE`` to ``".*"``.
+::
+
+    export OTEL_INSTRUMENTATION_HTTP_CAPTURE_HEADERS_SERVER_RESPONSE=".*"
+
+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:
+    The environment variable names used to capture HTTP headers are still experimental, and thus are subject to change.
+
 API
 ---
 


Test patch:
diff --git a/instrumentation/opentelemetry-instrumentation-django/tests/test_middleware.py b/instrumentation/opentelemetry-instrumentation-django/tests/test_middleware.py
--- a/instrumentation/opentelemetry-instrumentation-django/tests/test_middleware.py
+++ b/instrumentation/opentelemetry-instrumentation-django/tests/test_middleware.py
@@ -48,6 +48,7 @@
     format_trace_id,
 )
 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,
     _active_requests_count_attrs,
@@ -530,6 +531,14 @@ def test_django_with_wsgi_instrumented(self):
             )
 
 
+@patch.dict(
+    "os.environ",
+    {
+        OTEL_INSTRUMENTATION_HTTP_CAPTURE_HEADERS_SANITIZE_FIELDS: ".*my-secret.*",
+        OTEL_INSTRUMENTATION_HTTP_CAPTURE_HEADERS_SERVER_REQUEST: "Custom-Test-Header-1,Custom-Test-Header-2,Custom-Test-Header-3,Regex-Test-Header-.*,Regex-Invalid-Test-Header-.*,.*my-secret.*",
+        OTEL_INSTRUMENTATION_HTTP_CAPTURE_HEADERS_SERVER_RESPONSE: "Custom-Test-Header-1,Custom-Test-Header-2,Custom-Test-Header-3,my-custom-regex-header-.*,invalid-regex-header-.*,.*my-secret.*",
+    },
+)
 class TestMiddlewareWsgiWithCustomHeaders(WsgiTestBase):
     @classmethod
     def setUpClass(cls):
@@ -542,18 +551,9 @@ def setUp(self):
         tracer_provider, exporter = self.create_tracer_provider()
         self.exporter = exporter
         _django_instrumentor.instrument(tracer_provider=tracer_provider)
-        self.env_patch = patch.dict(
-            "os.environ",
-            {
-                OTEL_INSTRUMENTATION_HTTP_CAPTURE_HEADERS_SERVER_REQUEST: "Custom-Test-Header-1,Custom-Test-Header-2,Custom-Test-Header-3",
-                OTEL_INSTRUMENTATION_HTTP_CAPTURE_HEADERS_SERVER_RESPONSE: "Custom-Test-Header-1,Custom-Test-Header-2,Custom-Test-Header-3",
-            },
-        )
-        self.env_patch.start()
 
     def tearDown(self):
         super().tearDown()
-        self.env_patch.stop()
         teardown_test_environment()
         _django_instrumentor.uninstrument()
 
@@ -570,10 +570,18 @@ def test_http_custom_request_headers_in_span_attributes(self):
             "http.request.header.custom_test_header_2": (
                 "test-header-value-2",
             ),
+            "http.request.header.regex_test_header_1": ("Regex Test Value 1",),
+            "http.request.header.regex_test_header_2": (
+                "RegexTestValue2,RegexTestValue3",
+            ),
+            "http.request.header.my_secret_header": ("[REDACTED]",),
         }
         Client(
             HTTP_CUSTOM_TEST_HEADER_1="test-header-value-1",
             HTTP_CUSTOM_TEST_HEADER_2="test-header-value-2",
+            HTTP_REGEX_TEST_HEADER_1="Regex Test Value 1",
+            HTTP_REGEX_TEST_HEADER_2="RegexTestValue2,RegexTestValue3",
+            HTTP_MY_SECRET_HEADER="My Secret Value",
         ).get("/traced/")
         spans = self.exporter.get_finished_spans()
         self.assertEqual(len(spans), 1)
@@ -607,6 +615,13 @@ def test_http_custom_response_headers_in_span_attributes(self):
             "http.response.header.custom_test_header_2": (
                 "test-header-value-2",
             ),
+            "http.response.header.my_custom_regex_header_1": (
+                "my-custom-regex-value-1,my-custom-regex-value-2",
+            ),
+            "http.response.header.my_custom_regex_header_2": (
+                "my-custom-regex-value-3,my-custom-regex-value-4",
+            ),
+            "http.response.header.my_secret_header": ("[REDACTED]",),
         }
         Client().get("/traced_custom_header/")
         spans = self.exporter.get_finished_spans()
diff --git a/instrumentation/opentelemetry-instrumentation-django/tests/test_middleware_asgi.py b/instrumentation/opentelemetry-instrumentation-django/tests/test_middleware_asgi.py
--- a/instrumentation/opentelemetry-instrumentation-django/tests/test_middleware_asgi.py
+++ b/instrumentation/opentelemetry-instrumentation-django/tests/test_middleware_asgi.py
@@ -43,6 +43,7 @@
     format_trace_id,
 )
 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,
     get_excluded_urls,
@@ -424,6 +425,14 @@ async def test_tracer_provider_traced(self):
         )
 
 
+@patch.dict(
+    "os.environ",
+    {
+        OTEL_INSTRUMENTATION_HTTP_CAPTURE_HEADERS_SANITIZE_FIELDS: ".*my-secret.*",
+        OTEL_INSTRUMENTATION_HTTP_CAPTURE_HEADERS_SERVER_REQUEST: "Custom-Test-Header-1,Custom-Test-Header-2,Custom-Test-Header-3,Regex-Test-Header-.*,Regex-Invalid-Test-Header-.*,.*my-secret.*",
+        OTEL_INSTRUMENTATION_HTTP_CAPTURE_HEADERS_SERVER_RESPONSE: "Custom-Test-Header-1,Custom-Test-Header-2,Custom-Test-Header-3,my-custom-regex-header-.*,invalid-regex-header-.*,.*my-secret.*",
+    },
+)
 class TestMiddlewareAsgiWithCustomHeaders(SimpleTestCase, TestBase):
     @classmethod
     def setUpClass(cls):
@@ -437,18 +446,9 @@ def setUp(self):
         tracer_provider, exporter = self.create_tracer_provider()
         self.exporter = exporter
         _django_instrumentor.instrument(tracer_provider=tracer_provider)
-        self.env_patch = patch.dict(
-            "os.environ",
-            {
-                OTEL_INSTRUMENTATION_HTTP_CAPTURE_HEADERS_SERVER_REQUEST: "Custom-Test-Header-1,Custom-Test-Header-2,Custom-Test-Header-3",
-                OTEL_INSTRUMENTATION_HTTP_CAPTURE_HEADERS_SERVER_RESPONSE: "Custom-Test-Header-1,Custom-Test-Header-2,Custom-Test-Header-3",
-            },
-        )
-        self.env_patch.start()
 
     def tearDown(self):
         super().tearDown()
-        self.env_patch.stop()
         teardown_test_environment()
         _django_instrumentor.uninstrument()
 
@@ -465,12 +465,20 @@ async def test_http_custom_request_headers_in_span_attributes(self):
             "http.request.header.custom_test_header_2": (
                 "test-header-value-2",
             ),
+            "http.request.header.regex_test_header_1": ("Regex Test Value 1",),
+            "http.request.header.regex_test_header_2": (
+                "RegexTestValue2,RegexTestValue3",
+            ),
+            "http.request.header.my_secret_header": ("[REDACTED]",),
         }
         await self.async_client.get(
             "/traced/",
             **{
                 "custom-test-header-1": "test-header-value-1",
                 "custom-test-header-2": "test-header-value-2",
+                "Regex-Test-Header-1": "Regex Test Value 1",
+                "regex-test-header-2": "RegexTestValue2,RegexTestValue3",
+                "My-Secret-Header": "My Secret Value",
             },
         )
         spans = self.exporter.get_finished_spans()
@@ -510,6 +518,13 @@ async def test_http_custom_response_headers_in_span_attributes(self):
             "http.response.header.custom_test_header_2": (
                 "test-header-value-2",
             ),
+            "http.response.header.my_custom_regex_header_1": (
+                "my-custom-regex-value-1,my-custom-regex-value-2",
+            ),
+            "http.response.header.my_custom_regex_header_2": (
+                "my-custom-regex-value-3,my-custom-regex-value-4",
+            ),
+            "http.response.header.my_secret_header": ("[REDACTED]",),
         }
         await self.async_client.get("/traced_custom_header/")
         spans = self.exporter.get_finished_spans()
diff --git a/instrumentation/opentelemetry-instrumentation-django/tests/views.py b/instrumentation/opentelemetry-instrumentation-django/tests/views.py
--- a/instrumentation/opentelemetry-instrumentation-django/tests/views.py
+++ b/instrumentation/opentelemetry-instrumentation-django/tests/views.py
@@ -35,6 +35,13 @@ def response_with_custom_header(request):
     response = HttpResponse()
     response["custom-test-header-1"] = "test-header-value-1"
     response["custom-test-header-2"] = "test-header-value-2"
+    response[
+        "my-custom-regex-header-1"
+    ] = "my-custom-regex-value-1,my-custom-regex-value-2"
+    response[
+        "my-custom-regex-header-2"
+    ] = "my-custom-regex-value-3,my-custom-regex-value-4"
+    response["my-secret-header"] = "my-secret-value"
     return response