Manually handle graceful shutdown when SIGTERM is sent

[snoopcheri]

Hi

I'm running dind as a sidecar container in a Kubernetes pod. And I'm trying to make sure that the dind container doesn't shutdown immediately when receiving a SIGTERM, but waits for the main container to gracefully shutdown first.

In order to achieve this, I'm overwriting the entry point with a command /bin/sh -c <some script>, where <some script> registers a trap handler which does the synchronization. But it seems that busybox simply ignores SIGTERM. And since no bash is installed, I don't see any way around this.

I guess I could simply create a new image based on dind and install bash. But working with the dind image directly would be the preferred way.

Do you see a way how I could achieve this?

[tianon]

Unfortunately, I don't see a very clean way to accomplish what you're looking for, but installing bash in this image is pretty trivial (apk add --no-cache bash), and I'd also suggest that the behavior you're implementing is probably going to be easier to maintain over time with a custom image (thus making installing an extra package pretty easy).

You could also do something "clever" to chainload at runtime, like: sh -c 'apk add --no-cache bash && exec "$@"' -- bash -c '...'

(In the future, these sorts of questions/requests would be more appropriately posted to a dedicated support forum, such as the Docker Community Forums, the Docker Community Slack, or Stack Overflow.)