note on Azure Container Registry backing storage account layout

2026-08-06

the layer sharing thing of hierarchical repos, (u.acr.io/hier/a and u.acr.io/hier/b gets us storage free) is a bust; turns out it’s a side-effect of same {storage-replica} getting assigned during push that fastens the layer push; i’m guessing storage gets counted across layers anyway.

{digest-prefix} - here is the layer-digest, not the manifest digest.
{registry-id} - is fixed per container registry.
{storage-instance} - seems to be random as far as i can tell.

https://{storage-replica}.blob.core.windows.net/
  {digest-prefix}-{registry-id}-{storage-instance}/
  docker/registry/v2/blobs/sha256/{digest[0:2]}/{digest}/data

some {storage-replica} seen

cinreplica2
cinreplica9
cinreplica97
cinreplica199

interesting bits: storage accounts can scale to hundreds of thousands of containers here then, effectively.

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