Re: [atomic-devel] The atomic command and setting hostname for containers

[Jan Pazdziora <jpazdziora redhat com>]

On Wed, Feb 17, 2016 at 04:25:20PM +0100, Jan Pazdziora wrote:
> 
> It'd be nice if the atomic command could support -h option, and make
> that value available for use in the INSTALL / RUN / UNINSTALL LABELs.
> I envision something like
> 
> 	docker install -h ipa.example.com freeipa-server --realm EXAMPLE.COM ...
> 
> and
> 
> 	docker run freeipa-server
> 
> and be able to use
> 
> 	LABEL INSTALL 'docker run -h ${OPT_HOSTNAME} ... ${IMAGE} ...'
> 
> and
> 
> 	LABEL RUN 'docker run -h ${OPT_HOSTNAME} ... ${IMAGE} ...'
> 
> and have that OPT_HOSTNAME expand to
> 
> 	-h ipa.example.com

Dan notes that atomic run will start an existing container, so if the
user used the install to create a container with the -h flag, then
it would work properly.

I'm not sure we can rely on this in general case. The man page
atomic-install(1) shows an example LABEL INSTALL to be

	/usr/bin/docker run  -t -i --rm ... /bin/install.sh

With that --rm, the container is removed after the install.sh finishes,
so docker run has no existing container to use. Besides, INSTALL
would typically use

	--privileged -v /:/host

while RUN might want to run unprivileged and with a bunch of
(potentially read-only) specific directories and files bind-mounted.

So atomic run does not start existing container -- it needs to be
able to run a new one.

-- 
Jan Pazdziora
Senior Principal Software Engineer, Identity Management Engineering, Red Hat