fetch image tags and hashes

The latest docker registry api spec supports the retrieval of image tags and image hashes.

See tarsum spec See Docker Registry HTTP API V2


The tarsum normalizes a tar (sorting by file name, sorting extending attribute headers) and removes some information (timestamps) before calculating a hash. Specifically the hash includes the file contents and the following file attributes:

  • name - file name
  • mode - read, write, execute, ...
  • uid - user id
  • gid - group id
  • size - size of file
  • typeflag - file, directory, symlink, hardlink
  • linkname - if link
  • uname - user name
  • gname - group name
  • devmajor - for device
  • devminor - for device
  • extented attribute headers ("SCHILY.xattr." prefixed pax headers)