kontain.me serves Docker container images generated on-demand at the time they are requested.

These include:

• random.kontain.me, which serves randomly-generated images.
• mirror.kontain.me, which pulls and caches images from other registries.
• flatten.kontain.me, which pulls and flattens images from other registries, so they contain only one layer.
• kaniko.kontain.me, which builds a GitHub repo using Kaniko.
• ko.kontain.me, which builds a Go binary into a container image using ko.
• buildpack.kontain.me, which builds a GitHub repo using CNCF Buildpacks.
• estargz.kontain.me, which optimizes an image's layers for partial image pulls using estargz.
• wait.kontain.me, which enqueues a background task to serve a random image after some amount of time.

This repo also serves viz.kontain.me, which visualizes shared image layers using Graphviz.

Caveats

• The registry does not accept pushes.
• This is a silly hack and probably isn't stable. Don't rely on it for anything serious.
• It could probably do a lot of smart things to be a lot faster. 🤷
• Blobs and manifests are cached for 24 hours wherever possible, but will be rebuilt from scratch after that time.

How it works

The service is implemented using Google Cloud Run.

When the service receives a request for an image manifest, it parses the request and generates layers for the requested image, writing the manifest and blobs to Google Cloud Storage. After it receives the manifest, docker pull fetches the blobs. The app simply redirects to Cloud Storage to serve manifests and blobs.