fix(structlog): appends to default_processors via list to avoid TypeError [backport 2.2] (#7691)

Backport 0cfc263 from #7679 to 2.2.

Fixes #7665 by changing `default_processors` to list accounting for all
types of iterables before appending

## Checklist

- [x] Change(s) are motivated and described in the PR description.
- [x] Testing strategy is described if automated tests are not included
in the PR.
- [x] Risk is outlined (performance impact, potential for breakage,
maintainability, etc).
- [x] Change is maintainable (easy to change, telemetry, documentation).
- [x] [Library release note
guidelines](https://ddtrace.readthedocs.io/en/stable/releasenotes.html)
are followed. If no release note is required, add label
`changelog/no-changelog`.
- [x] Documentation is included (in-code, generated user docs, [public
corp docs](https://github.com/DataDog/documentation/)).
- [x] Backport labels are set (if
[applicable](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting))

## Reviewer Checklist

- [x] Title is accurate.
- [x] No unnecessary changes are introduced.
- [x] Description motivates each change.
- [x] Avoids breaking
[API](https://ddtrace.readthedocs.io/en/stable/versioning.html#interfaces)
changes unless absolutely necessary.
- [x] Testing strategy adequately addresses listed risk(s).
- [x] Change is maintainable (easy to change, telemetry, documentation).
- [x] Release note makes sense to a user of the library.
- [x] Reviewer has explicitly acknowledged and discussed the performance
implications of this PR as reported in the benchmarks PR comment.
- [x] Backport labels are set in a manner that is consistent with the
[release branch maintenance
policy](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting)
- [x] If this PR touches code that signs or publishes builds or
packages, or handles credentials of any kind, I've requested a review
from `@DataDog/security-design-and-guidance`.
- [x] This PR doesn't touch any of that.

Co-authored-by: Zarir Hamza <[email protected]>
Co-authored-by: Munir Abdinur <[email protected]>

Author: 3 people

ddtrace/contrib/structlog/patch.py

@@ -48,8 +48,18 @@ def _tracer_injection(_, __, event_dict):
 
 
 def _w_get_logger(func, instance, args, kwargs):
+    """
+    Append the tracer injection processor to the ``default_processors`` list used by the logger
+    The ``default_processors`` list has built in defaults which protects against a user configured ``None`` value.
+    The argument to configure ``default_processors`` accepts an iterable type:
+        - List: default use case which has been accounted for
+        - Tuple: patched via list conversion
+        - Set: ignored because structlog processors care about order notably the last value to be a Renderer
+        - Dict: because keys are ignored, this essentially becomes a List
+    """
+
     dd_processor = [_tracer_injection]
-    structlog._config._CONFIG.default_processors = dd_processor + structlog._config._CONFIG.default_processors
+    structlog._config._CONFIG.default_processors = dd_processor + list(structlog._config._CONFIG.default_processors)
     return func(*args, **kwargs)
 
 

releasenotes/notes/fix_structlog_processor_list-037c90b391dbfbc2.yaml

@@ -0,0 +1,4 @@
+---
+fixes:
+  - |
+    structlog: Fixes ``TypeError`` raised when ddtrace log processor is configured with a tuple

tests/contrib/structlog/test_structlog_logging.py

@@ -259,3 +259,88 @@ def test_log_DD_TAGS():
 
     cf.logger.calls.clear()
     unpatch()
+
+
+@pytest.mark.subprocess()
+def test_tuple_processor_list():
+    """
+    Regression test for: https://github.com/DataDog/dd-trace-py/issues/7665
+    """
+    import json
+
+    import structlog
+
+    from ddtrace import config
+    from ddtrace import tracer
+    from ddtrace.contrib.structlog import patch
+    from ddtrace.contrib.structlog import unpatch
+
+    config.service = "logging"
+    config.env = "global.env"
+    config.version = "global.version"
+
+    patch()
+
+    cf = structlog.testing.CapturingLoggerFactory()
+    structlog.configure(
+        processors=(structlog.stdlib.add_log_level, structlog.processors.JSONRenderer()),
+        logger_factory=cf,
+    )
+    logger = structlog.getLogger()
+
+    span = tracer.trace("test.logging")
+    logger.info("Hello!")
+    span.finish()
+
+    output = cf.logger.calls
+
+    assert json.loads(output[0].args[0])["event"] == "Hello!"
+    assert json.loads(output[0].args[0])["dd.trace_id"] == str(span._trace_id_64bits)
+    assert json.loads(output[0].args[0])["dd.span_id"] == str(span.span_id)
+    assert json.loads(output[0].args[0])["dd.env"] == "global.env"
+    assert json.loads(output[0].args[0])["dd.service"] == "logging"
+    assert json.loads(output[0].args[0])["dd.version"] == "global.version"
+
+    cf.logger.calls.clear()
+    unpatch()
+
+
+@pytest.mark.subprocess()
+def test_no_configured_processor():
+    """
+    Check if injected values are present when no processor is configured
+    """
+    import structlog
+
+    from ddtrace import config
+    from ddtrace import tracer
+    from ddtrace.contrib.structlog import patch
+    from ddtrace.contrib.structlog import unpatch
+
+    config.service = "logging"
+    config.env = "global.env"
+    config.version = "global.version"
+
+    patch()
+
+    cf = structlog.testing.CapturingLoggerFactory()
+    structlog.configure(
+        logger_factory=cf,
+    )
+    logger = structlog.getLogger()
+
+    span = tracer.trace("test.logging")
+    logger.info("Hello!")
+    span.finish()
+
+    output = cf.logger.calls
+
+    assert "Hello!" in output[0].args[0]
+    assert "dd.trace_id={}".format(str(span._trace_id_64bits)) in output[0].args[0]
+    assert "dd.span_id={}".format(str(span.span_id)) in output[0].args[0]
+    assert "dd.env=global.env" in output[0].args[0]
+    assert "dd.service=logging" in output[0].args[0]
+    assert "dd.version=global.version" in output[0].args[0]
+
+    cf.logger.calls.clear()
+    unpatch()