[FEATURE] dedicated metric for number of images not-pulled with SOCI ( defer )

[lukasmrtvy]

Description

Would be superb to have such a metric to be able to determine how many images were pulled ( with SOCI lazy pull ) vs images pulled without SOCI. That includes invalid or missing indexes ( defer ).

Describe the solution you'd like

No response

Describe any alternative solutions/features you've considered

No response

Any additional context or information about the feature request

No response

[lukasmrtvy]

#277 does not solve the use case when index is missing

[Kern--]

What use-case do you have in mind?

We already emit metrics for failures to setup image layers, so we could add a layer_mounted metric with a dimension of lazy, local, or parallel (with better names than that).

But that would tell you information about layers, not images. Would that be enough? Or do you want to answer questions like "We expect all images to use SOCI, how many were missing indexes?"

[lukasmrtvy]

What use-case do you have in mind?

"cache" hit/miss metric

"We expect all images to use SOCI, how many were missing indexes?"

Yes. Of course, one can compare indexes vs images directly in registries, but especially when using async Lambda ( https://awslabs.github.io/cfn-ecr-aws-soci-index-builder/ ), this kind of info would make sense to have.

[Kern--]

I think this makes sense. I'll add it to our backlog, but we would also accept a contribution here.