Filecoin v1 retrievals

V1 retrievals on Filecoin are done using HTTP range requests to Storage providers hosting the files. Currently, this requires that you provide multiple pieces of information:

• A metadata.yml file that specifies the way that the full epoch car file was split into Filecoin pieces

• A deals.csv file that maps the individual Filecoin pieces to storage providers

A sample config file for an epoch using Filecoin v1 retrievals would look like this:

version: 1
epoch: 100
data:
  car:
    from_pieces:
      deals:
        uri: '/of1/100/deals.csv'
      metadata:
        uri: '/of1/100/metadata.yaml'
indexes:
  cid_to_offset_and_size:
    uri: /of1/100/epoch-100-bafyreibqt2nvroysxlxctgb52xxn27ectsllv2xyka4qar7ga6vupmbs3i-mainnet-cid-to-offset-and-size.index
  slot_to_cid:
    uri: /of1/100/epoch-100-bafyreibqt2nvroysxlxctgb52xxn27ectsllv2xyka4qar7ga6vupmbs3i-mainnet-slot-to-cid.index
  sig_to_cid:
    uri:  /of1/100/epoch-100-bafyreibqt2nvroysxlxctgb52xxn27ectsllv2xyka4qar7ga6vupmbs3i-mainnet-sig-to-cid.index
  sig_exists:
    uri: /of1/100/epoch-100-bafyreibqt2nvroysxlxctgb52xxn27ectsllv2xyka4qar7ga6vupmbs3i-mainnet-sig-exists.index
  gsfa:
    uri: /of1/100/epoch-100-bafyreibqt2nvroysxlxctgb52xxn27ectsllv2xyka4qar7ga6vupmbs3i-mainnet-gsfa.indexdir

All indexes except gsfa can use either a local file system URL or an HTTP URL.