Allow custom project-specific entrypoint

[michaelbaudino]

As suggested by @GCorbel (thanks 🎩), we could allow the user to execute some project-specific shell script (some beloved shell aliases, for example) before any command run in the container.

It could be a new very simple entrypoint like that:

#!/bin/bash

CUSTOM_ENTYRYPOINT="/app/.entrypoint-additions.sh"

[ -x "${CUSTOM_ENTYPOINT}" ] && . "${CUSTOM_ENTRYPOINT}"

exec "$@"

It would let users have a .entrypoint-additions.sh script in their project root with commands to execute after the image default entrypoint(s).

It should not be used for cpu- or network-intensive commands, though (like apt-get install or gem install), otherwise I guarantee that users will go insane soon (it's executed before every command, even to start a shell).

[GCorbel]

I'm not sure but entrypoint are not included when we build the image, right ? If it's the case, what would be the advantage of using this instead of docker-compose ? My first idea was to include some stuff on the build, like installing some gems or some libs. Maybe the best would be to create another image based on yours.

What do you think?

[michaelbaudino]

Ha, sorry I probably misunderstood it the first time.

What you're looking for is indeed building a new image based on this very one, then, as we recommend in the Customisation section of the RECIPES book.

Did I get it right this time?