feat: make log format configurable

[Kraego]

Since I had problems with the encoding of the colored json log in the OKD shell (see Image), I've made the logformat configurable.

[codspeed-hq]

CodSpeed Performance Report

Merging #4851 will degrade performances by 27.98%

_{Comparing Kraego:main (d14f0e9) with main (2de119b)}

Summary

⚡ 2 improvements
❌ 1 regressions
✅ 12 untouched benchmarks

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

	Benchmark	main	Kraego:main	Change
⚡	test_successful_run_with_input_type_any	233.2 ms	143.1 ms	+62.89%
❌	test_successful_run_with_input_type_text	232 ms	322.1 ms	-27.98%
⚡	test_successful_run_with_output_type_debug	231.1 ms	153.8 ms	+50.21%

[Kraego]

Would it be better to use LANGFLOW_LOG_ENV? Just found the variable in the code, currently there is no decription in the environments_variables.md for this setting.

imho: Setting the format directly will give the user more flexibility and is less implicit than the log environments but comes with the downside of configuration errors in the logging which will make diagnostics pretty hard.

If the maintainers decide that LANGFLOW_LOG_ENV should be used for my usecase, I will change this PR to just containing the needed additions in the documentation for this env var.

[ogabrielluiz]

Hey @Kraego

How are you?

This is a valid problem. If we were to use LANGFLOW_ENV we'd have to build something like the following to check for valid format strings:

import logging

def is_valid_log_format(format_string):
    """Validates a logging format string by attempting to format it with a dummy LogRecord.

    Args:
        format_string (str): The format string to validate.

    Returns:
        bool: True if the format string is valid, False otherwise.
        str: Error message if invalid, empty string if valid.
    """
    record = logging.LogRecord(
        name="dummy",
        level=logging.INFO,
        pathname="dummy_path",
        lineno=0,
        msg="dummy message",
        args=None,
        exc_info=None
    )

    formatter = logging.Formatter(format_string)

    try:
        # Attempt to format the record
        formatter.format(record)
    except (KeyError, ValueError, TypeError) as e:
        # Formatting failed, return False and the error message
        msg = f"Invalid log format string: {format_string}"
        raise ValueError(msg) from e
    return True

What do you think?

[Kraego]

Hi @ogabrielluiz,

thanks I am doing well hope you too ...

As far as I see:

• Option1: LANGFLOW_ENV has hard defined log formats in the code, so if you think this is sufficient for the user all we have to do is provide a documentation of this settings
• Option2: If you think providing the full flexibility of complete custom log formats, Yes I think such a check method would be necessary and also a seperate env variable for configuration + LANGFLOW_ENV could/should have a documentation.

Both Options above will resolve my problem.

What option should I implement?

[Kraego]

I've added your proposed format string check

[ogabrielluiz]

Thanks @Kraego !

LGTM

[Kraego]

@ogabrielluiz now ready for merge

[ogabrielluiz]

Hey @Kraego

Sounds good!

I'll merge it ASAP. You can leave it out of date because it will only merge when no other PR is merging.