Add structlog.contextvars.merge_contextvars to default config

CHANGELOG.md

@@ -72,6 +72,8 @@ So please make sure to **always** properly configure your applications.
 - `structlog.processors.format_exc_info()` is no longer a function, but an instance of `structlog.processors.ExceptionRenderer`.
   Its behavior has not changed.
   [#407](https://github.com/hynek/structlog/pull/407)
+- The default configuration now includes the `structlog.contextvars.merge_contextvars` processor.
+  That means you can use [`structlog.contextvars`](https://www.structlog.org/en/stable/contextvars.html) features without configuring `structlog`.
 
 
 ### Fixed

docs/getting-started.rst

@@ -48,6 +48,7 @@ Using the defaults, as above, is equivalent to::
 
    structlog.configure(
        processors=[
+           structlog.contextvars.merge_contextvars,
            structlog.processors.add_log_level,
            structlog.processors.StackInfoRenderer(),
            structlog.dev.set_exc_info,

pyproject.toml

@@ -226,7 +226,7 @@ If you prefer videos over reading, check out `Markus Holtermann <https://twitter
 Project Information
 ===================
 
-- **License**: dual-licensed under `Apache License, version 2 <https://choosealicense.com/licenses/apache/>`_ and `MIT <https://choosealicense.com/licenses/mit/>`_
+- **License**:  *dual* `Apache License, version 2 and MIT <https://www.structlog.org/en/stable/license.html>`_
 - **PyPI**: https://pypi.org/project/structlog/
 - **Source Code**: https://github.com/hynek/structlog
 - **Documentation**:  https://www.structlog.org/

src/structlog/_config.py

@@ -24,6 +24,7 @@
 
 from ._log_levels import make_filtering_bound_logger
 from ._loggers import PrintLoggerFactory
+from .contextvars import merge_contextvars
 from .dev import ConsoleRenderer, _use_colors, set_exc_info
 from .processors import StackInfoRenderer, TimeStamper, add_log_level
 from .types import BindableLogger, Context, Processor, WrappedLogger
@@ -36,6 +37,7 @@
    - structlog.stdlib.recreate_defaults()'s docstring.
 """
 _BUILTIN_DEFAULT_PROCESSORS: Sequence[Processor] = [
+    merge_contextvars,
     add_log_level,
     StackInfoRenderer(),
     set_exc_info,

src/structlog/stdlib.py

@@ -20,13 +20,13 @@
 from functools import partial
 from typing import Any, Callable, Collection, Iterable, Sequence
 
-from structlog.processors import StackInfoRenderer
-
 from . import _config
 from ._base import BoundLoggerBase
 from ._frames import _find_first_app_frame_and_name, _format_stack
 from ._log_levels import _LEVEL_TO_NAME, _NAME_TO_LEVEL, add_log_level
+from .contextvars import merge_contextvars
 from .exceptions import DropEvent
+from .processors import StackInfoRenderer
 from .types import Context, EventDict, ExcInfo, Processor, WrappedLogger
 
 
@@ -83,6 +83,7 @@ def recreate_defaults(*, log_level: int | None = logging.NOTSET) -> None:
     _config.reset_defaults()
     _config.configure(
         processors=[
+            merge_contextvars,
             add_log_level,
             StackInfoRenderer(),
             _config._BUILTIN_DEFAULT_PROCESSORS[-2],  # TimeStamper