canonicalization: Add recommendations for canonicalization #339
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| # Canonicalization | ||
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| OCI Images [are](descriptor.md) [content-addressable](image-layout.md). | ||
| One benefit of content-addressable storage is easy deduplication. | ||
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Contributor
There was a problem hiding this comment. It's already explicitly called out as a goal @ https://github.com/opencontainers/image-spec/blame/e74c6c703315a8d2baaea691b527194377c33a8d/manifest.md#L4
Contributor
Author
There was a problem hiding this comment. Ah, I stand corrected. I still think the current wording covers that though. Would you still prefer your initial suggestion? |
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| Many images might depend on a particular [layer](layer.md), but there will only be one blob in the [store](image-layout.md). | ||
| With a different serialization, that same semantic layer would have a different hash, and if both versions of the layer are referenced there will be two blobs with the same semantic content. | ||
| To allow efficient storage, implementations serializing content for blobs SHOULD use a canonical serialization. | ||
| This increases the chance that different implementations can push the same semantic content to the store without creating redundant blobs. | ||
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| ## JSON | ||
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| [JSON][] content SHOULD be serialized as [canonical JSON][canonical-json]. | ||
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Contributor
There was a problem hiding this comment. JSON content (for example, ...)
Contributor
There was a problem hiding this comment. JSON content (for example all of the bla bla media types or bla bla manifests) SHOULD be serialized as |
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| Of the [OCI Image Format Specification media types](media-types.md), all the types ending in `+json` contain JSON content. | ||
| Implementations: | ||
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| * [Go][]: [github.com/docker/go][], which claims to implement [canonical JSON][canonical-json] except for Unicode normalization. | ||
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| [canonical-json]: http://wiki.laptop.org/go/Canonical_JSON | ||
| [github.com/docker/go]: https://github.com/docker/go/ | ||
| [Go]: https://golang.org/ | ||
| [JSON]: http://json.org/ | ||
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Slightly more intro context - something like "One of the goals of the OCI Image Specification is to leverage content-addressable storage (CAS), which provides benefits like easy deduplication"