`dumb-init` swallows SegFault error logs from NodeJS

[tchupp]

Pretty much the title!

I haven't investigated other languages, as NodeJS has a relatively easy reproducible example. I imagine whatever is running inside dumb-init is less important here anyways.

~Minimum~ Small reproducible example

$ docker run --rm -it --entrypoint /bin/sh node:18-alpine3.15

> cd

> apk add python3 python2 libexecinfo libexecinfo-dev g++ make vim dumb-init

> npm install node-segfault-handler

> vim index.js
let segfaultHandler = require('node-segfault-handler');
segfaultHandler.segfault();

> echo "enough setup already!"
...

> node index.js
Segmentation fault (core dumped)

> echo $?
139

> dumb-init node index.js

> echo $?
139

> node index.js
Segmentation fault (core dumped)

> dumb-init node index.js

[asottile]

the shell is printing that, this has nothing to do with dumb-init

[tchupp]

Do you mind elaborating a little bit?

[asottile]

your shell is printing "Segmentation fault (core dumped)" -- for example try:

$ python3 -c "import subprocess; print(subprocess.call(('node', 'index.js')))"
-11

[tchupp]

Ah, interesting! So the monitor in the shell that prints "Segmentation faul (core dumped)" isn't basing that on the exit code then.

Thank you for pointing me in the right direction 😁 I found more info here that helped me understand what was going on: https://martin.uy/blog/who-prints-core-dumped-after-a-segmentation-fault/