Export images as Prometheus metrics

[ArjonBu]

What would you like to be added:
Add a metrics endpoint to expose currently running images as Prometheus metrics

Why is this needed:
Nice to have. We could use this information for other purposes outside Anchore.

[dakaneye]

@ArjonBu thanks for the feature suggestion. To clarify, are you requesting a metrics endpoint on the Anchore service? Or a flag that can be provided to kai such that the output of the images matches something that can be imported into Prometheus?

[ArjonBu]

@dakaneye a metrics endpoint on KAI which can be scrapped by Prometheus. This metrics endpoint should show the same info that KAI sends to Anchore (image, namespace of the image, etc...)

[zburstein]

@ArjonBu Thanks for suggesting the feature! I have submitted the request to PM for review

[zhill]

@ArjonBu, I'm not quite sure I understand the specific suggestion. Is the ask for a metric value for each image? For example a metric label "centos:latest" with integer value 1 indicating that one image with that tag is running, and another metric "debian:latest" with 3, for 3 images running in the namespace with that tag.

Prometheus metrics are typically numeric, whereas KAI reports a list of names that can change on each invocation, so the metrics, if keyed by the image name or digest, would be dynamic. If that is ok then I understand the ask. Just looking for what you would want to graph in Grafana, for example. That would help clarify. Thanks!

[ArjonBu]

The metric would have labels for the deployment name (if possible), image tag, namespace and cluster name with the value 1.
Generally all metrics would have the value 1.