Registry Explorer

Registry Explorer

This beautiful tool allows you to explore the contents of a registry interactively.

You can even drill down into layers to explore an image's filesystem.

Enter a public image, e.g. "ubuntu:latest":

Enter a public repository, e.g. "ubuntu":

Interesting examples


How does this work?

This service lives on Cloud Run and uses google/go-containerregistry for registry interactions.

Isn't this expensive for the registry?

Not really! The first time a layer is accessed, I download and index it. Browsing the filesystem just uses that index, and opening a file uses Range requests to load small chunks of the layer as needed.

That can't be true, gzip doesn't support random access!

That's not a question.

Okay then, how does random access work if the layers are gzipped tarballs?

Great question! See here.

Tl;dr, you can seek to an arbitrary position in a gzip stream if you know the 32KiB of uncompressed data that comes just before it, so by storing ~1% of the uncompressed layer size, I can jump ahead to predetermined locations and start reading from there rather than reading the entire layer.

Thanks @aidansteele!

Is this open source?

Yes! See here.