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ghcr Artifact Storage

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Rick Guo edited this page Jun 23, 2026 · 1 revision

GHCR Artifact Store

GHCR is the default Artifact Store backend for LLAR binary artifacts.

Storage Shape

package = ghcr.io/<owner>/<module>
tag     = <version>
matrix  = OCI index manifest annotation org.llar.matrix = <MatrixStr>
blob    = artifact archive layer

One GHCR package stores one LLAR module. One tag stores one module version. The tag points to an OCI image index. Each matrix variant is one manifest entry in that index.

OCI Layout

ghcr.io/<owner>/<module>:<version>
  OCI image index
    manifest entry
      annotations:
        org.llar.matrix = <MatrixStr>
      platform:
        os           = <os>
        architecture = <arch>
      image manifest
        layer
          media type = application/vnd.oci.image.layer.v1.tar+gzip
          content    = artifact.tar.gz

platform.os and platform.architecture should be filled when the selected matrix has those values. LLAR artifact matching uses org.llar.matrix.

Blob URL

The uploader publishes the archive blob, writes or updates the version index, and returns the final blob URL:

https://ghcr.io/v2/<owner>/<module>/blobs/sha256:<digest>

llar install detects GHCR downloads from the URL host. Public GHCR blob downloads use:

Authorization: Bearer Qq==

Example

For madler/zlib@v1.3.1:

package = ghcr.io/llar-artifacts/madler/zlib
tag     = v1.3.1
matrix  = org.llar.matrix = amd64-linux
blob    = artifact.tar.gz

OCI layout:

ghcr.io/llar-artifacts/madler/zlib:v1.3.1
  OCI image index
    manifest entry
      annotations:
        org.llar.matrix = amd64-linux
      platform:
        os           = linux
        architecture = amd64
      image manifest
        layer
          media type = application/vnd.oci.image.layer.v1.tar+gzip
          content    = artifact.tar.gz
          digest     = sha256:2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824
    manifest entry
      annotations:
        org.llar.matrix = arm64-darwin
      platform:
        os           = darwin
        architecture = arm64
      image manifest
        layer
          media type = application/vnd.oci.image.layer.v1.tar+gzip
          content    = artifact.tar.gz
          digest     = sha256:486ea46224d1bb4fb680f34f7c9ad96a8f24ec88be73ea8e5a6c65260e9cb8a7

Returned artifact URL for amd64-linux:

https://ghcr.io/v2/llar-artifacts/madler/zlib/blobs/sha256:2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824

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