ansilogs

Colored, single-line log output for command-line tools. A small, dependency-free replacement for coloredlogs.install() with the same default look.

import logging

import ansilogs

ansilogs.install(logging.DEBUG)
logging.getLogger(__name__).warning("careful")

2026-10-19 09:35:12 my-host my_tool.cli[4242] WARNING careful

• One line per record: <time> <host> <name>[<pid>] <LEVEL> <message>; tracebacks follow uncolored.
• Colors only when stderr is a terminal. NO_COLOR (non-empty) disables them, FORCE_COLOR (non-empty) forces them. On Windows the console is switched to ANSI processing; if that fails, output is plain.
• Records go to whatever sys.stderr is at the time (test capture and live progress displays that redirect stderr keep working).

API

• install(level=logging.INFO, colors=None): attach the handler to the root logger (once) and show records from level up. colors=None means supports_color().
• set_level(level): change the shown level (installs the handler if needed).
• supports_color(stream=None): the color decision used by install().
• ColoredFormatter(colors=True, hostname=None) and StderrHandler for custom setups.

Migrating from coloredlogs

-import coloredlogs
-coloredlogs.install(level=logging.DEBUG)
+import ansilogs
+ansilogs.install(logging.DEBUG)

coloredlogs.set_level(level) becomes ansilogs.set_level(level). COLOREDLOGS_* environment variables and custom field/level styles are not supported.