I'm interacting with a closed Spring Boot jar I can't edit (actually, I don't even have access to th...

# server

[Fred Friis]

I'm interacting with a closed Spring Boot jar I can't edit (actually, I don't even have access to the jar, I'm just editing the Docker run arguments when it gets booted in the cloud somewhere)

by default, Spring Boot doesn't pipe logs or sysout anywhere, it just displays it in console and that's it

there is a logging.file=blabla config attribute you can tweak to make it do it

but I don't have access to the prod.yml etc files

= can I just -Dlogging.file=/dev/stdout when booting the app and that should "take"?

[Sam]

What do you mean by 'console', if not stdout?

[Sam]

If it's displaying in the console, that means it is going to stdout, and you can do whatever else you want with it from there

[Sam]

Unless I've misunderstood your message entirely

[Sam]

Afaik that is best practice for dockerised apps -- à la 12-factor

[Fred Friis]

haha you're right, I guess what I'm asking is in case I also want to write it to the file

dev/stdout

and I don't have access to the config files, nor the jar itself lol, will telling Docker to send in the run arg

-Dlogging.file=/dev/stdout

when it boots the jar take care of that?

[Fred Friis]

in my case, there should be another docker sidecar "listening" for logs there and piping them to splunk

[ashmelev]

You can also try nohup - i.e. something like:

nohup <spring startup & args> > nohup.out

and your logs will be appended to nohup.out

[Sam]

Not sure I understand the distinction between the 'file' and the console. Won't /dev/stdout just act as a link to the process' own output stream anyway? (The one it's already writing to)

[Fred Friis]

oh dang I didn't realize what's showing up in console is actually the same thing as /dev/stdout

if that's the case, what's weird is, our Splunk sidecar should be listening there, but we don't see anything show up in Splunk

= either output and logs are not being piped there, or it is and the Splunk sidecar is in fact seeing it there but failing to stream that on to our Splunk somehow

[Fred Friis]

actually on confirmation booting the image locally using docker run, I do get the normal spring output in the terminal (=console)

but if I docker exec -it /bin/bash into the running container and less /dev/stdout, there's nothing there 🤔

[Sam]

Afaik /dev/stdout points to the output stream of the current process

[Sam]

So I assume less /dev/stdout would just show its own output, which is breaking my mind so I'm not going to think about that too hard

[Fred Friis]

😆

[CLOVIS]

if that's the case, what's weird is, our Splunk sidecar should be listening there, but we don't see anything show up in Splunk

You can't listen to /dev/stdout . The only thing in there is what the current process itself is writing.