Set default ENTRYPOINT

[zakame]

This installs and sets tini as the default ENTRYPOINT for Perl images, to enable Perl programs in containers to handle signals correctly, particularly on SIGINT/SIGTERM.

Ref. #44

[mohawk2]

Bump? (also there are conflicts that would need some TLC)

[zakame]

Yes, the conflicts are from the lone commit regenerating Dockerfiles, which can be dropped.

I think we just need to check on whether users are (usually) customizing ENTRYPOINT (or not,) and documenting for least astonishment.

[mohawk2]

Hmm. Search all of GitHub's Perl repos for such usage? I guess docs would be needed in any case. I seriously doubt anyone is relying on the current behaviour of not doing signals right? ;-)

[sdt]

Is this now covered by the --init flag to docker run ?

[zakame]

@sdt yes, though as #44 (comment) notes we can't rely on --init for running outside of Docker, such as in k8s.

@mohawk2 right, we've had a doc for this since docker-library/docs#1550, which could do with an update (e.g. maybe mention https://github.com/openSUSE/catatonit as another alternative, or use sigtrap ... if handling from Perl natively.)