SIGTERM not caught in docker container using foreground (OTP 19.3)

[macpie]

Since OPT 19.3

erts: A received SIGTERM signal to beam will generate a 'stop' message to the init process and terminate the Erlang VM nicely. This is equivalent to calling init:stop/0.

So I wanted to pair that with docker stop command to get a proper stop for my application.

docker stop

The main process inside the container will receive SIGTERM, and after a grace period, SIGKILL.

It is recommended to use foreground with docker, problem is, it does not seems to catch the SIGTERM. I then realized that foreground is using the +Bd flag. Which seems to interfere with the ability to catch the SIGTERM.

Option d (same as specifying +B without an extra option) disables the break handler. Option i makes the emulator ignore any break signal.

Does foreground really need that flag? Should there be an extra command for this case?

PS: I fixed this by using console and flags _build/default/rel/app/bin/legacy console -noshell -noinput which I find acceptable. The only difference, that I could find, between console and foreground are those 3 flags -noshell -noinput +Bd

[tsloughter]

Ah, crap! We did add that :(. Ugh, now I wish we hadn't. It wasn't an issue when Erlang didn't respect SIGTERM...

Going to have to mull this over.

[macpie]

Yes OTP catching SIGTERM is nice. Nevertheless doing console -noshell -noinput is ok for me.

Thanks for looking!

[tsloughter]

Hm, looks like this could be fixed in 19.3.2:

OTP-14358 Application(s): erts Related Id(s): OTP-14085

            The +Bi command line argument of erl erroneously caused
            SIGTERM to be ignored by the VM as well as of all its
            child processes. This bug was introduced in erts
            version 8.3.

[macpie]

@tsloughter sweet will give it a try

[macpie]

fixed indeed