Add support for FORCE_COLOR (#503)

fixes #495

.github/workflows/ci.yml

@@ -199,3 +199,22 @@ jobs:
         uses: re-actors/alls-green@release/v1
         with:
           jobs: ${{ toJSON(needs) }}
+
+
+  colors:
+    name: Visual check for color settings using env variables
+    needs: build-sdist
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Get source code from pre-built sdist
+        uses: re-actors/checkout-python-sdist@release/v1
+        with:
+          source-tarball-name: ${{ env.sdist-name }}
+          workflow-artifact-name: ${{ env.sdist-artifact }}
+      - uses: actions/setup-python@v4
+        with:
+          python-version: ${{env.PYTHON_LATEST}}
+      - run: python -Im pip install tox wheel
+
+      - run: tox -f color

CHANGELOG.md

@@ -18,6 +18,11 @@ You can find out backwards-compatibility policy [here](https://github.com/hynek/
 ### Added
 
 - `structlog.stdlib.BoundLogger` now has, analogously to our native logger, a full set of async log methods prefixed with an `a`: `await log.ainfo("event!")`
+  [#502](https://github.com/hynek/structlog/issues/502)
+
+- The default configuration now respects the presence of `FORCE_COLOR` (regardless of its value except empty string).
+  This disables all heuristics whether it makes sense to use colors.
+  [#338](https://github.com/hynek/structlog/issues/338)
 
 
 ### Fixed

src/structlog/_config.py

@@ -9,6 +9,7 @@
 
 from __future__ import annotations
 
+import os
 import sys
 import warnings
 
@@ -35,10 +36,13 @@
     set_exc_info,
     TimeStamper(fmt="%Y-%m-%d %H:%M:%S", utc=False),
     ConsoleRenderer(
-        colors=_has_colors
-        and sys.stdout is not None
-        and hasattr(sys.stdout, "isatty")
-        and sys.stdout.isatty()
+        colors=os.environ.get("FORCE_COLOR") is not None
+        or (
+            _has_colors
+            and sys.stdout is not None
+            and hasattr(sys.stdout, "isatty")
+            and sys.stdout.isatty()
+        )
     ),
 ]
 _BUILTIN_DEFAULT_CONTEXT_CLASS = cast(Type[Context], dict)

tox.ini

@@ -73,6 +73,12 @@ commands =
     coverage report
 
 
+[testenv:color-force]
+help = A visual check that FORCE_COLOR is working.
+set_env = FORCE_COLOR=1
+commands = python -c "import structlog; structlog.get_logger().warning('should be colorful')"
+
+
 [testenv:docset]
 deps = doc2dash
 extras = docs