Add graceful shutdown

[sylvain-reynaud]

The container doesn’t shutdown gracefully. To stop it, I have to run docker rm -f <container_name>.

The container should shutdown gracefully for the reasons explained in the 12factor app: https://12factor.net/disposability

I would like to work on it, is it possible ?

[amaury1093]

Sure. @sylvain-reynaud Could you clarify what exactly is your proposed solution?

[sylvain-reynaud]

Ideally:

• start a new thread to handle the SIGINT/SIGTERM signals
• close HTTP request handles,
• finish current HTTP requests then close DB connections

[amaury1093]

That works for me. If you want to create a PR, I'll review (and approve) it.