do not require custom build of tini

[glensc]

- What I did

the original implementation #28037 by @crosbymichael required custom build of tini that does not have option parser (requested in krallin/tini#55)
but it can be accomplished without need for such custom build by just using -- to stop argument parsing.

- How I did it

adds -- argument when calling init reaper allowing flags from CMD not to interfere with init own commandline arguments

krallin/tini#55 (comment)
krallin/tini#55 (comment)
#28037

- How to verify it

# docker run --init --rm -it ubuntu echo 123

- Description for the changelog

Do not require custom build of tini.

- A picture of a cute animal (not mandatory but encouraged)

[crosbymichael]

The only problem I have with this change is that to have the init swappable, not all inits have flags like tini did and if they don't, they will accept -- as an arg and pass it to exec. We made the change so that we have a contract with all inits, that you passthrough all arguments and there is nothing to parse or interpret.

[glensc]

@crosbymichael well. it's the same way the opposite: you can't use init that parses options, like tiny was initially.

[crosbymichael]

Yes, and that is why we changed tini and added the flag, so it wouldn't

[glensc]

btw, what init daemons you had in mind? i'm pretty sure sysv init, systemd init and upstart init don't pass argv to command to execute and follow them. there must be used init process specifically written for the docker purpose.

[cpuguy83]

What's the status here?

[AkihiroSuda]

@crosbymichael WDYT about @glensc 's question?

[justincormack]

I think it is pointless making init swappable, if people really want to we can specify the exact contract. If people want a particular init they should add it to their image, or bind mount it in themselves. So fine with making it as upstream is.

…

On 19 Jan 2017 8:04 a.m., "Akihiro Suda" ***@***.***> wrote: @crosbymichael <https://github.com/crosbymichael> WDYT about @glensc <https://github.com/glensc> 's question? — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#28454 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAdcPKrRQQYvbPfIApMFKScKMHHq5EMnks5rTxkOgaJpZM4KzFcX> .

[crosbymichael]

LGTM

[LK4D4]

LGTM