Provide a no-onbuild version

[josegonzalez]

ONBUILD kinda sucks if it requires adding files that don't exist. Would be great if we could avoid onbuild completely for a non-custom logspout version :)

[josegonzalez]

For reference, I'm adding a git:from-image command to Dokku, but this fails with gliderlabs/logspout because there is no build.sh to add from the current build context as the only thing available is the Dockerfile with the contents of FROM gliderlabs/logspout:v3.2.13.

[airdrummingfool]

I am looking for this as well, because I want to provide a custom entrypoint script. As a workaround, empty build.sh and modules.go files can be used.

[modem7]

A multistage image with entrypoint scripts would be the best way forward.

Not to mention Alpine 3.12 is woefully out of date.