ORAS: OCI Registry As Storage
Shriira Press
How a container registry quietly became universal storage for every software artifact — and the small tool that made it possible.
Welcome to ORAS: OCI Registry As Storage.
For years the container registry was a single-purpose machine: it held images, and only images. ORAS rethinks that assumption. The same registries that already sit at the heart of every cloud-native deployment — Docker Hub, GitHub Container Registry, Azure Container Registry, Harbor — turn out to be perfectly capable of storing any content you can break into bytes: Helm charts, WebAssembly modules, machine-learning models, configuration bundles, signatures, and software bills of materials. ORAS is the command-line tool and family of SDKs that unlocks this, treating media types as a first-class concept and using the OCI distribution and image specifications as a generic, content-addressable storage protocol. This book starts with the problem ORAS solves and the OCI specifications it stands on, then works through manifests and media types, the push and pull workflow, the referrers API that links signatures and SBOMs to the images they describe, OCI image layouts on the local filesystem, copying artifacts between registries, and finally the oras-go and oras-py SDKs that let you build registry-native applications of your own.
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— Shriira Press