Non-terminal signals are killing containers running with --init flag about tini HOT 3 CLOSED

I think this means your process doesn't have a handler for SIGUSR2 registered; from signal(7) (https://manpages.debian.org/bullseye/manpages/signal.7.en.html#Standard_signals), SIGUSR2 is a terminating signal by default.

from tini.

Hm, I didn't know SIGUSRs are terminating by default, that's why used a random web server as example, sorry. But initially this issue happened with my own image which has a SIGUSR2 handler. I've created a POC repo: https://github.com/rayrapetyan/test_sig.

Steps to reproduce the issue:

1. Run cmd.sh locally
2. See output:

PID of this script: 433226
Running....
Running....
...

3. Send SIGUSR2 signal: kill -SIGUSR2 433226
4. Notice signal was intercepted in cmd.sh:

handling SIGUSR2
Running....

and process continues running as expected.

Now run cmd.sh from container:

docker build -t test_sig:latest .
docker run --rm --init --name test_sig test_sig:latest

Send SIGUSR2:
docker kill --signal SIGUSR2 test_sig

Expected: cmd.sh running inside a docker container should receive and handle a signal and continue running.
Actual: container stops.

Now after looking into how cmd.sh is running inside a container:
/sbin/docker-init -- /bin/sh -c ./cmd.sh -> bash cmd.sh
I realize that because of /bin/sh is running before bash, it's intercepting all signals and doesn't forward them to a child processes (bash) properly?

from tini.

Works when running as:
docker run --rm --init --name test_sig test_sig:latest ./cmd.sh
so no /bin/sh in between.

from tini.