Show cause of "core commands are not available"

[amenk]

I would be cool to show the last error message of bin/magento in case the core commands are not available.

Especially in CI logs, this might allow quicker debugging.

[cmuench]

@amenk the latest n98-magerun2 version proxy all call to any core command. It's just calling bin/magento.
Error messages should be used.
Do you mean we should print a part of the error log? Maybe I do not fully understand your idea. Can you give me a hint?

[cmuench]

Ok. Got it. I will check that.

[cmuench]

I was not able to reproduce it. I get the same output. The error output is respected.
My error also looks different as in your example (same cache:flush command).

That's the output on a current Mage-OS 1.0.6 with a not accessible redis cache server.

[amenk]

okay, I seem to get the same output now. No clue what changed. in My first test I got the backtrace in bin/magento but not in n98-mager2. But what's more important:
If I use a command that is only defined in bin/magento I just get:

$ n98-magerun2 varnish:vcl:generate
Magento Core Commands cannot be loaded. Please verify if "bin/magento" is running.
Run with -vvv option to see the error output.
Only n98-magerun2 commands are available until the issue is fixed.

                                                                 
  There are no commands defined in the "varnish:vcl" namespace.  

So in this case I do not see any error message from bin/magento

$ bin/magento 
Connection to Redis standalone tcp://localhost:6379 failed after 2 failures.Last Error : (0) php_network_getaddresses: getaddrinfo for localhost failed: Name or service not known

So in a CI or so log this would be hard to debug.
We currently work around this by just directly calling bin/magento in such cases.

[cmuench]

That's an interesting finding.

[cmuench]

That's an interesting finding.

We load the core commands by using "php bin/magento --format=json".
If this does not provide infos we do not know any core command. Could be that this is the cause of the difference.
I am not sure if we should then do a fallback with all arguments to "bin/magento" or supress the error message "There are no commands defined in the...".
I think supressing the misleading message is better. If bin/magento is broken then it's a broken core system.