Hey maybe your Docker file contains something like this:

CMD ["/bin/node", "app.js"]

Oh no this is no good! - TLDR: Your process can get shutdown in a bad way and zombie processes will eat your container!

Instead just use smell-baron and change your Dockerfile to:

ADD smell-baron /bin/smell-baron
ENTRYPOINT ["/bin/smell-baron"]
CMD ["/bin/node", "app.js" ]

Now you don't have to worry anymore!

smell-baron is written in c so you don't need anything installed in the host machine to use the binary and it consumes almost no resources.

To build a release version:

make release

To build a debug version:

make

Or to build a copy against Centos5's glibc (so it can run on more machines) first install docker, then run this as a user with access to docker:

./build-release.sh

It can also be build on alpine to link against musl rather than glibc:

./build-release.sh alpine

You can also get a prebuilt binary from github (but don't trust me, build it yourself):

wget https://github.com/ohjames/smell-baron/releases/download/v0.3.0/smell-baron
chmod a+x smell-baron

If you want to run multiple processes you can separate them with the argument ---:

ADD smell-baron /bin/smell-baron
ENTRYPOINT ["/bin/smell-baron"]
CMD ["/bin/runit", "---", "/bin/node", "app.js" ]

smell-baron will wait for every process to exit before sending a SIGTERM to the remaining (reaped) processes. It will exit when all child processes exit.

This behaviour can be altered with the -f command-line argument:

smell-baron -f sleep 1 --- sleep 2

When -f is used then the remaining processes will be killed with SIGTERM after the process specified first exits. In the above example sleep 2 would be killed after one second.