Improve logging for functions during error about faas HOT 6 CLOSED

Every fprocess has only two sure ways to communicate with its fwatchdog atm: stdout and stderr. Beside these there is also the exit status code. So in my view :

For fprocess:

• stdout : ONLY valid result data must be printed here (e.g a final json object). No warning, error, debug output.
• stderr: ALL messages related to the execution of the fprocess (trace, debug, warn, error..).

For fwatchdog:

• Always print fprocess's stderr on its stdout.
• Never print fprocess's stdout on its stdout (because you can already get it on the fprocess container easily).
• In case of fprocess success, send a http response with fprocess's stdout content and Http.Ok status (200).
• In case of fprocess failure, send a http response with fprocess's stderr content and Http.Error status (500).
• No panic in case of fprocess failure.

These are of course suggestions to be debated. Cheers.

from faas.

See also: b7d2845

from faas.

Agreed on this point - I will create an issue to track documenting it.

For fprocess:
stdout : ONLY valid result data must be printed here (e.g a final json object). No warning, error, debug output.
stderr: ALL messages related to the execution of the fprocess (trace, debug, warn, error..).

from faas.

Hi @thejibz please could you review the current behaviour and get back to me?

from faas.

@aafrey @vegasbrianc @nicolaka do you guys have any thoughts here?

from faas.

@thejibz I've updated the latest watchdog code so that it will return the full stdout/stderr output upon error. Will close issue for now - can re-open if we need more granularity.

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