Logging in Fontshow¶

Fontshow uses a structured, centralized logging model designed to be:

Logging is treated as part of the public behavior of the tool, not as an implementation detail.

1. Design principles¶

Fontshow uses one single logger:

logging.getLogger("fontshow")

This logger is:

There are no per-module loggers.

Modules must not:

All configuration is centralized in:

src/fontshow/core/logging_utils.py

All logs use structured payloads:

logger.info(
    "font inventory parsing started",
    extra={
        "schema_version": schema_version,
        "fonts_count": len(fonts),
    },
)

Rules:

The file src/fontshow/core/logging_utils.py is the only place where logging is configured.

Responsibilities:

It must not:

Each module must:

from fontshow.logging_utils import logger

And then use:

logger.info(...)
logger.warning(...)
logger.error(...)

❌ Do NOT use:

logging.getLogger(__name__)

❌ Do NOT create new loggers.

This allows:

Tests assume:

Example test assertion:

assert "font inventory parsing started" in messages

❌ Do not use:

❌ Do not configure logging in:

This design allows:

It also avoids the most common Python logging pitfalls.

✔ One logger ✔ Structured messages ✔ Centralized config ✔ Test-friendly ✔ CLI-safe

This is the only supported logging model in Fontshow.