How to use structlog with fastapi and fly.io

I’ve started using structlog everywhere instead of the built-in python logging module. Here’s a quick run-down of how I’ve been setting it up. I’m sure there are better ways to do a number of these things. Link to docs.

poetry add structlog

# In each file where you want to log:

import structlog
logger = structlog.get_logger()

# In the main file or settings.py file include:

# Set up the logger
log_level = os.getenv("LOG_LEVEL", "DEBUG")
log_format = os.getenv("LOG_FORMAT", "JSON")
log_service = os.getenv("LOG_SERVICE_NAME", "unknown")


def add_service(_, __, event_dict: Dict) -> Dict:
    event_dict["service"] = log_service
    return event_dict


log_processors = [
    # structlog.stdlib,
    # structlog.stdlib.add_logger_name,
    structlog.processors.TimeStamper(fmt="iso"),
    structlog.processors.CallsiteParameterAdder(
        [
            structlog.processors.CallsiteParameter.FILENAME,
            structlog.processors.CallsiteParameter.FUNC_NAME,
            structlog.processors.CallsiteParameter.LINENO,
        ],
    ),
    structlog.stdlib.add_log_level,
    structlog.processors.StackInfoRenderer(),
    structlog.processors.format_exc_info,
    structlog.processors.ExceptionPrettyPrinter(),
    add_service,
]


# Make sure that the renderers are last in processors
if log_format.lower() == "json":
    log_processors.append(structlog.processors.JSONRenderer())
else:
    # Console renderer
    log_processors.append(structlog.dev.ConsoleRenderer())


# python3.11 has this mapping built into the logging module.
# https://docs.python.org/3/library/logging.html#logging-levels
LOG_LEVEL_MAPPER = {
    "CRITICAL": 50,
    "ERROR": 40,
    "WARNING": 30,
    "INFO": 20,
    "DEBUG": 10,
    "NOTSET": 0,
}
log_level_int = LOG_LEVEL_MAPPER[log_level]
wrapper = structlog.make_filtering_bound_logger(log_level_int)
structlog.configure(
    processors=log_processors,
    wrapper_class=wrapper,
)


logger = structlog.get_logger()