Expose image type (ext3/squashfs) with inspect

[kav2k]

Version of Singularity:

2.4.2-dist

Expected behavior

It is expected that inspect (or another singularity command) is able to tell that an image is immutable or not.

Actual behavior

No such information is currently exposed.

In fact, there's no way to determine it using singularity itself, other than trying to run a container with --writeable and detecting the error.

As a workaround, this produces the required information:

SINGULARITY_MESSAGELEVEL=0 /usr/local/libexec/singularity/bin/image-type some_image.simg

However, it's desirable to be able to get this information with standard commands.

[ArangoGutierrez]

I think we must first discuss how we want to read this info

Here I show a 0.1 proposal for this feature.

singularity inspect nginx.img 
{
    "org.label-schema.usage.singularity.deffile.bootstrap": "docker",
    "maintainer": "NGINX Docker Maintainers <docker-maint@nginx.com>",
    "org.label-schema.usage.singularity.deffile": "Singularity",
    "org.label-schema.schema-version": "1.0",
    "org.label-schema.usage.singularity.deffile.includecmd": "no",
    "org.label-schema.usage.singularity.deffile.from": "nginx",
    "org.label-schema.build-date": "Tue,_23_Jan_2018_17:39:21_-0500",
    "org.label-schema.usage.singularity.version": "2.4.1-release-2.4.g56581cf3",
    "org.label-schema.build-size": "111MB"
    "org.label-schema.image-format": "squash,ext3,tar" << Proposal
}

[vsoch]

@ArangoGutierrez the specification is here: http://label-schema.org/rc1/ the namespace needs to fall under singularity then some label. I would suggest starting even simpler than that - if the user asks for

singularity inspect -f <container> 

The ``-f(or-if`) would signify image format, and the entrypoint to inspect would use the `SINGULARITY_libexecdir` to target the executable, change the message level to 0 to be quiet, and then call it to return the format.

singularity inspect -f <container> 
SQUASHFS

and thus it's basically a wrapper for the command that already exists. For the integration with the other json, since we are transitioning to go it would be ok to wait to re-write that code, although you could follow suit with calling the executable (or using the function I wrote to get the format) and then returning the same thing. Up to you!

[carterpeel]

Hello,

This is a templated response that is being sent out to all open issues. We are working hard on 'rebuilding' the Singularity community, and a major task on the agenda is finding out what issues are still outstanding.

Please consider the following:

1. Is this issue a duplicate, or has it been fixed/implemented since being added?
2. Is the issue still relevant to the current state of Singularity's functionality?
3. Would you like to continue discussing this issue or feature request?

Thanks,
Carter

[vsoch]

This will also eventually be valuable for perhaps using singularity containers with OCI. It was more of an issue before when there were more image types, and now probably it would help to show the version of SIF.

[stale]

This issue has been automatically marked as stale because it has not had activity in over 60 days. It will be closed in 7 days if no further activity occurs. Thank you for your contributions.

[vsoch]

Don't close stalebot, the contributors to this issue have responded and it's the maintainers that have not.

[pedroalvesbatista]

@kav2k We're looking into the issue carefully, soon will bring to community and discuss ways to better solve as well address this. Thankyou for keeping the interest in the subject.

[kmuriki]

Copied into Apptainer new issue #491. Closing this in the old Singularity repo.