Voting Ledger Snapshots

With snapshots of the voting ledger published hourly, anyone can verify that recorded votes remain unchanged across the voting lifecycle.

The Catalyst team provides access to routine snapshots of the blockchain state. These snapshots are automatically taken at 1-hour intervals and uploaded to a persistent storage system in the form of an archive. Currently, these archives can be found by querying the Archive API . You can learn more about the available endpoints by inspecting the Swagger documentation

To show an example of how to interact with the API and download an archive, we will use the curl and jq CLI tools. First, we must list the available archives:

> curl -s https://archiver.projectcatalyst.io/api/v1/archives/ | jq
{
  "next": "",
  "archives": [
    {
      "id": "019fd6b2-c36b-419f-8a2d-ebf06b91a762",
      "size": 364315029,
      "compression": "zstd",
      "packaging": "tar",
      "metadata": {
        "epoch": "1952",
        "fund": "fund10",
        "slot": "14",
        "timestamp": "2023-08-29T18:00:59Z"
      }
    },
    {
      "id": "64c56031-56ab-43dd-a1ca-138a85298d2b",
      "size": 372405154,
      "compression": "zstd",
      "packaging": "tar",
      "metadata": {
        "epoch": "1954",
        "fund": "fund10",
        "slot": "17",
        "timestamp": "2023-08-29T20:01:09Z"
      }
    },
    {
      "id": "ad16b160-0cc2-4252-ae61-f468c95cbf29",
      "size": 364453534,
      "compression": "zstd",
      "packaging": "tar",
      "metadata": {
        "epoch": "1953",
        "fund": "fund10",
        "slot": "23",
        "timestamp": "2023-08-29T19:01:34Z"
      }
    }
  ]
}

In the above response, there are only three archives available. Should the number of results exceed 50, they will automatically be paginated. This is made evident by the next field being set. To fetch subsequent archives, you would call the same endpoint and append ?next={VALUE} where VALUE is the value of the next field. To iterate over all available archives, you can repeat this process until the next field is empty.

For this example, we’ll choose to fetch the first archive in the list. To get a link for downloading the archive, we can run:

> curl -q https://archiver.projectcatalyst.io/api/v1/archives/019fd6b2-c36b-419f-8a2d-ebf06b91a762/download | jq
{
  "url": "https://archives.projectcatalyst.io/prod/019fd6b2-c36b-419f-8a2d-ebf06b91a762?Expires=1693341938&Signature=R5CJdg4GZCHHGakePZJIHaYHSOthO-RuIAuiGwcLTnD3MZrtxUMWQFvLdSpWrl6dqPB6VNNeS5sMp9pK7x-JmuBvnZ3XZNUEcBA9XLlMgIZJQDD7l6JEgCtKWRiOFPbOSUZSLQMhD6mbL2koARzdZjkzLDjPFFf33~vU89qZzt-VaaMseDUtGv-6zU6ANh2RkUvWD9UCUDTwoU9VjrMhwPfrx2kaWGIkt5a3NqxkNmti7SVdwtcsKWN7wuLQNaks-PJnrTKwtp7Qc8Ll3vrf846vJWzH3UVDwDB0vbk1nVcysijEaj6m7DcWA5TR7Di84FHjYf9zmTJYeeC71Ht8mw__&Key-Pair-Id=K36UOCCH06A5FV"
}

This endpoint returns a time-sensitive URL to download the archive. Note that this URL is only valid for 15 minutes. To download the archive:

> URL="$(curl -s https://archiver.projectcatalyst.io/api/v1/archives/019fd6b2-c36b-419f-8a2d-ebf06b91a762/download | jq -r .url)"
> curl -o archive.tar.zstd "$URL"

We save the file as a .tar .zstd archive because this is how the contents were archived. If you look back at the API response, you’ll see the compression and packaging fields were set to zstd and tar respectively. We can use these fields to determine the process for extracting the archive. To extract the contents, we’ll need to use the .tar and .zstd CLIs:

> zstd -d archive.tar.zstd && tar -xvf archive.tar
archive.tar.zstd    : 523103232 bytes
artifacts
artifacts/block0.bin
permanent
permanent/blocks
permanent/blocks/data
permanent/blocks/seqno
permanent/chain_length
permanent/chain_length/data
permanent/chain_length/seqno
volatile
volatile/blobs
volatile/conf
volatile/db
volatile/snap.00000003A7319A1C

We now have a complete snapshot of the blockchain state on our local filesystem.