Re: [Buildroot] [PATCH] fs/oci: entrypoint and command are space-separated lists

From: Peter Korsgaard <peter@korsgaard.com>
To: Arnout Vandecappelle <arnout@mind.be>
Cc: yann.morin@orange.com, Sergio Prado <sergio.prado@e-labworks.com>,
	Matthew Weber <matthew.weber@collins.com>,
	buildroot@buildroot.org
Subject: Re: [Buildroot] [PATCH] fs/oci: entrypoint and command are space-separated lists
Date: Fri, 13 May 2022 22:54:38 +0200	[thread overview]
Message-ID: <87fsld886p.fsf@dell.be.48ers.dk> (raw)
In-Reply-To: <d31498c0-ae87-12ed-eae6-6efbd37bcca2@mind.be> (Arnout Vandecappelle's message of "Fri, 13 May 2022 21:42:00 +0200")

>>>>> "Arnout" == Arnout Vandecappelle <arnout@mind.be> writes:

Hi,

 >> >  If you really need spaces, you can still use $(space). So,
 >> after
 >> >  adding single quotes, the following should work:
 >> > BR2_TARGET_ROOTFS_OCI_ENTRYPOINT_ARGS="date;$(space)date"
 >> Nice and easy for newcomers :P

 >  Sure, but do you have an actual use case where you want spaces in the
 >  CMD or ENTRYPOINT? Note that even in the Dockerfile itself you need
 > to switch to JSON syntax to support that case. I think it's
 > exceedingly rare.

Sorry, what do you mean? If I have a silly container like:

FROM busybox

CMD for i in 1 2 3; do date; done

Then that works fine (as CMD expands to sh -c "<args>" if you don't use
the array format).

docker inspect <container> | jq '.[] | .Config.Cmd'
[
  "/bin/sh",
  "-c",
  "for i in 1 2 3; do date; done"
]

I don't think I have ever seen embedded spaces in ENTRYPOINT (but I have
seen multiple arguments), but in CMD I have.

 >  If you really have such complicated cases, you're probably better off
 >  doing it with a post-image script that imports the tarball after
 > all. But the simple case that covers 95% of the use cases can be
 > covered by fs/oci.

I would argue that just doing docker (or podman) import in the
post-image script is easier than fs/oci as people doing container stuff
are likely to already know docker and Dockerfiles, but oh well.

 >> >  That requires a docker daemon installed on the host, while
 >> >  sloci-image can be run as normal user without any host support
 >> > required.
 >> s/docker import/podman import/.

 >  So it requires a podman daemon installed on the host... podman can do
 >  rootless containers, but it's still mediated by the daemon.

No, podman is daemon-less.

-- 
Bye, Peter Korsgaard
_______________________________________________
buildroot mailing list
buildroot@buildroot.org
https://lists.buildroot.org/mailman/listinfo/buildroot