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-fastapi/src/opentelemetry/instrumentation/fastapi/__init__.py b/instrumentation/opentelemetry-instrumentation-fastapi/src/opentelemetry/instrumentation/fastapi/__init__.py
--- a/instrumentation/opentelemetry-instrumentation-fastapi/src/opentelemetry/instrumentation/fastapi/__init__.py
+++ b/instrumentation/opentelemetry-instrumentation-fastapi/src/opentelemetry/instrumentation/fastapi/__init__.py
@@ -34,8 +34,9 @@ async def foobar():
 
 Exclude lists
 *************
-To exclude certain URLs from being tracked, set the environment variable ``OTEL_PYTHON_FASTAPI_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_FASTAPI_EXCLUDED_URLS``
+(or ``OTEL_PYTHON_EXCLUDED_URLS`` to cover all instrumentations) to a string of comma delimited regexes that match the
+URLs.
 
 For example,
 
@@ -45,7 +46,7 @@ async def foobar():
 
 will exclude requests such as ``https://site/client/123/info`` and ``https://site/xyz/healthcheck``.
 
-You can also pass the comma delimited regexes to the ``instrument_app`` method directly:
+You can also pass comma delimited regexes directly to the ``instrument_app`` method:
 
 .. code-block:: python
 
@@ -54,9 +55,12 @@ async def foobar():
 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.
 
 .. code-block:: python
 
@@ -76,54 +80,93 @@ 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 FastAPI 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 fastapi 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=".*"
+
+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.
 
-Example of the added span attribute,
+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 FastAPI 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 fastapi 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:
-    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
 ---


Test patch:
diff --git a/instrumentation/opentelemetry-instrumentation-fastapi/tests/test_fastapi_instrumentation.py b/instrumentation/opentelemetry-instrumentation-fastapi/tests/test_fastapi_instrumentation.py
--- a/instrumentation/opentelemetry-instrumentation-fastapi/tests/test_fastapi_instrumentation.py
+++ b/instrumentation/opentelemetry-instrumentation-fastapi/tests/test_fastapi_instrumentation.py
@@ -32,6 +32,7 @@
 from opentelemetry.test.globals_test import reset_trace_globals
 from opentelemetry.test.test_base import TestBase
 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,
@@ -529,24 +530,23 @@ def test_mark_span_internal_in_presence_of_span_from_other_framework(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 TestHTTPAppWithCustomHeaders(TestBase):
     def setUp(self):
         super().setUp()
-        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()
         self.app = self._create_app()
         otel_fastapi.FastAPIInstrumentor().instrument_app(self.app)
         self.client = TestClient(self.app)
 
     def tearDown(self) -> None:
         super().tearDown()
-        self.env_patch.stop()
         with self.disable_logging():
             otel_fastapi.FastAPIInstrumentor().uninstrument_app(self.app)
 
@@ -559,6 +559,9 @@ async def _():
             headers = {
                 "custom-test-header-1": "test-header-value-1",
                 "custom-test-header-2": "test-header-value-2",
+                "my-custom-regex-header-1": "my-custom-regex-value-1,my-custom-regex-value-2",
+                "My-Custom-Regex-Header-2": "my-custom-regex-value-3,my-custom-regex-value-4",
+                "My-Secret-Header": "My Secret Value",
             }
             content = {"message": "hello world"}
             return JSONResponse(content=content, headers=headers)
@@ -573,12 +576,20 @@ 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]",),
         }
         resp = self.client.get(
             "/foobar",
             headers={
                 "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",
             },
         )
         self.assertEqual(200, resp.status_code)
@@ -602,6 +613,9 @@ def test_http_custom_request_headers_not_in_span_attributes(self):
             headers={
                 "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",
             },
         )
         self.assertEqual(200, resp.status_code)
@@ -623,6 +637,13 @@ 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]",),
         }
         resp = self.client.get("/foobar")
         self.assertEqual(200, resp.status_code)
@@ -653,24 +674,23 @@ def test_http_custom_response_headers_not_in_span_attributes(self):
             self.assertNotIn(key, server_span.attributes)
 
 
+@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 TestWebSocketAppWithCustomHeaders(TestBase):
     def setUp(self):
         super().setUp()
-        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()
         self.app = self._create_app()
         otel_fastapi.FastAPIInstrumentor().instrument_app(self.app)
         self.client = TestClient(self.app)
 
     def tearDown(self) -> None:
         super().tearDown()
-        self.env_patch.stop()
         with self.disable_logging():
             otel_fastapi.FastAPIInstrumentor().uninstrument_app(self.app)
 
@@ -688,6 +708,12 @@ async def _(websocket: fastapi.WebSocket):
                         "headers": [
                             (b"custom-test-header-1", b"test-header-value-1"),
                             (b"custom-test-header-2", b"test-header-value-2"),
+                            (b"Regex-Test-Header-1", b"Regex Test Value 1"),
+                            (
+                                b"regex-test-header-2",
+                                b"RegexTestValue2,RegexTestValue3",
+                            ),
+                            (b"My-Secret-Header", b"My Secret Value"),
                         ],
                     }
                 )
@@ -727,6 +753,13 @@ def test_web_socket_custom_request_headers_in_span_attributes(self):
 
         self.assertSpanHasAttributes(server_span, expected)
 
+    @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.*",
+        },
+    )
     def test_web_socket_custom_request_headers_not_in_span_attributes(self):
         not_expected = {
             "http.request.header.custom_test_header_3": (
@@ -799,16 +832,15 @@ def test_web_socket_custom_response_headers_not_in_span_attributes(self):
             self.assertNotIn(key, server_span.attributes)
 
 
+@patch.dict(
+    "os.environ",
+    {
+        OTEL_INSTRUMENTATION_HTTP_CAPTURE_HEADERS_SERVER_REQUEST: "Custom-Test-Header-1,Custom-Test-Header-2,Custom-Test-Header-3",
+    },
+)
 class TestNonRecordingSpanWithCustomHeaders(TestBase):
     def setUp(self):
         super().setUp()
-        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",
-            },
-        )
-        self.env_patch.start()
         self.app = fastapi.FastAPI()
 
         @self.app.get("/foobar")