Re: [atomic-devel] I would like to discuss a new IMAGE label to indicate whether an image is a --system image.

[Daniel J Walsh <dwalsh redhat com>]

On 11/09/2016 05:49 AM, Giuseppe Scrivano wrote:
> Hi,
>
> Daniel J Walsh <dwalsh redhat com> writes:
>
>> One problem I have with this is forgetting to use the --system flag when
>> installing the container.
>>
>> I would like to add a LABEL to the image that would tell atomic command
>> to install using the --system
>>
>> method.  This label would not be a generic label, since other tools
>> might not implement the concept of a
>>
>> system container.  I guess we could add a label like
>>
>> LABEL org.projectatomic.atomic.type=system
>>
>> Then this would cause atomic to use the --system flag?
> Thinking more of it, I am not sure how we can do this automatically for
> generic images.  An image can be used either as a system container, or
> as a traditional Docker container, so we will need to specify two
> different types.
>
> Is it going to be used for images that are usable only as system
> containers?
>
> Even in this simplified case, another issue is the storage we are
> considering. System images are stored in an OSTree repository.  When we
> use --system we are referring to these images.
>
> If we do not explicitely specify the storage then it will be a problem
> to know what image we are referring to.  An image can be in a storage
> and not in the other, or even worse the two storages could have a
> different image referred by the same name.  This will become even more
> complicated if in the future we'll need to support more image types.
>
> An alternative would be a label like:
>
> LABEL org.projectatomic.atomic.is_system=true
>
> that says the image can be used as a system container, or even simpler
> if the image is stored into the OSTree storage.
>
> When an user tries to install an image that has such label (or present
> in OSTree) and no INSTALL label, we could print a message suggesting to
> try --system, skipping the automatic assumption of it.
>
> Or alternatively, could we tweak the INSTALL label to print an error
> message for images that can be used only as system containers?
>
> Regards,
> Giuseppe
Yes I see storage as a different matter.

Currently we by default install into "docker storage" by default on install.
But we install into ostree under /var/lib/containers/atomic when user
specifies
atomic install --system.  In the short future, we will see the
introduction of
github.com/containers/storage, which will give us a third option.

But --system also implies the use of a systemd template stored in
/exports on the container
image.   I think this is the more important feature then the storage.

Having

LABEL io.projectatomic.atomic.is_system=true


And having
atomic install SYSTEM-IMAGE

Fail or automatically install with --system would be ok, although

atomic install SYSTEM-IMAGE
>Error: You must install SYSTEM-IMAGE with the --system flag

Aggravates me as a user,   If the tool knows I need the --system flag,
then just set it itself.