afch-logger

Logger for Azure Function Custom Handler, abusing the undocumented (at least I don't know where) rule of e Function "infering" the log level from stderr.

Usage

You can initialize the log by afch_logger::init_logger. If you want to use the replacement logic in other logger, you can call afch_logger::to_error_log to get the replaced error log, and afch_logger::contains_warn to test whether the message contains warn (case insensitive).

Strategy

For Azure Function Custom Handler, if you print a message to stdout, it will be considered as a Information level log by Azure Function runtime.

If you print a message to stderr, then it will be consider Error if it does not contain warn (case insensitive), otherwise it will be Warning.

So the strategy is, for error-level log, we find the occurence of warn and replace r by 𝗋(\U+1d5cb) and R by 𝖱(\U+1d5b1). For warning-level log, if warn does not occur, we add a warning: prefix.