Show stderr when error occurs on command execution

[isimluk]

Awesome spawn is used to run external utilities. Sometimes rare error occurs, then we through exception like this:

AwesomeSpawn::CommandResultError: psql exit code: 2

Usually there is an stderr that is contains useful details that could help admins, operators, supporters, developers and qa. Let's publish this stderr to give quick clue.

[coveralls]

Coverage remained the same at 100.0% when pulling 5c53830 on isimluk:publish-stderr-when-problem-occurs into 77519d4 on ManageIQ:master.

[miq-bot]

Checked commit https://github.com/isimluk/awesome_spawn/commit/5c53830b9613f0f6edba9cb02a569deef1bca428 with ruby 2.2.6, rubocop 0.47.1, and haml-lint 0.20.0
1 file checked, 0 offenses detected
Everything looks good. 🏆

[gtanzillo]

LGTM 👍

[gtanzillo]

@jrafanie Please review

[jrafanie]

LGTM, we might have suppressed the error in case there were passwords or something else logged or printed from standard error. It's probably better to just fix those rare occasions where we need to sanitize the output.

Do we need to truncate the standard error output in case it's really long? If needed, we can do a followup PR.

[isimluk]

Thanks!!

Note that if the password is written to stderr, it is not our bug. The problem would be in the tool we run.

[Fryguy]

I'm less concerned about passwords specifically than I am about other information, such as IP addresses on STDERR.

[jrafanie]

Yeah, it's really anything containing sensitive information that you may not want to capture from STDERR. But, it feels like we shouldn't cripple our ability to diagnose problems by not capturing anything so I'd rather we try to have clients sanitize command STDERR data when they consume this.