[release-5.10] copy: compute blob compression on reused blobs based on source MediaType #1162
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When copying a compressed blob without making any modifications to it, set the CompressionFormat in the returned BlobInfo to reflect the compression algorithm that was used to compress the blob. Signed-off-by: Nalin Dahyabhai <[email protected]>
When copying blobs, if we end up reusing a blob from the destination with the same digest as that given in the srcInfo, but don't know how that reused blob was compressed, compute the compression information from the MediaType included in the srcInfo, if one was supplied. Signed-off-by: Nalin Dahyabhai <[email protected]>
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I'll cut a new release in a jiffy. |
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Teach BlobInfoCache2 implementations to be able to retrieve the type of compression that was applied to a blob with a given digest, if we know it.
If we successfully reuse a blob while writing an image, and we know how a blob with that reused blob's digest was compressed, use that information when updating the MIME type for the reused blob.
This covers situations where TryReusingBlob() returns a BlobInfo containing a different digest and MIME type than the one we originally asked it to reuse. copy.imageCopier.copyLayers() sets it up as part of the LayerInfos in update info that copy.imageCopier.copyUpdatedConfigAndManifest() passes to src.UpdatedImage(), and the UpdateLayerInfos() implementations discard the MIME type from the new BlobInfo in favor of the MIME type in the original layers list.
The buildah blob cache triggers this case when we use it while pushing an image where the local copy of the manifest specifies an uncompressed digest and MIME type, and the blob cache tries to substitute the digest of the compressed version in LayerInfosForCopy(), since it knows it can retrieve the compressed version from its cache. The blob cache doesn't get used very often, so we've only recently started noticing it since we started testing #1089 in openshift/origin#25830.
Cherry picked from #1138.