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Publishing Data

Pragma makes publishing data easy because there is no off-chain infrastructure, so publishing only requires signing and timestamping data before sending it on-chain. All of this can be done with a simple, stateless node that costs a few dollars a month to run.

Estimated Time: A few hours to a day depending on your underlying data infrastructure.

SDK Version: This walkthrough is only valid for the SDK versions >=2.0.0.

Here is the step-by-step breakdown:

1. Account Setup​

We highly recommend using keystores instead of plain private keys for security.

starkli signer keystore new /path/to/key.json
export STARKNET_KEYSTORE="/path/to/key.json"
starkli account oz init /path/to/account.json
starkli account deploy /path/to/account.json

For more info you can look up here starkli.

2. Register your account contract address with Pragma​

Currently, publisher registration is permissioned while we create a robust ecosystem of publishers that will enable the transition to being a completely open network. During that initial phase, publishers send their publisher ID (the felt-encoded uppercased string, e.g. FLOWDESK) and account contract address to the Pragma team. Publishers should also publish their account contract address/public key online so that third parties can verify their identity with them directly.

3. Set up the data fetching logic​

To simplify the process of setting up a publisher, we provide an optional Docker base image and a Python SDK which can make it easier to get started. The process to integrate usually takes an hour to half a day.

The initial publishing frequency for the oracle is every 3 minutes on Starknet Sepolia testnet, we expect to move to single-digit seconds as the network matures and value secured grows.

3.1. Using the Pragma Python SDK​

Install the SDK in your virtual environment

pip install pragma-sdk

Full installation instructions can be found here

See a full sample script here, or copy paste the code below to get started.

Note that you need to set environment variables PUBLISHER, PUBLISHER_ADDRESS, and PUBLISHER_KEYSTORE_PASSWORD before running the code. You can use the sample .env file here to set them (the file does not include PUBLISHER_KEYSTORE_PASSWORD for obvious reasons).

To make fetching data simple, implement your own fetching function using whatever libraries you want, as long as it returns a List[Entry].

A few notes on expected parameters:

  • If you are a Market Maker/Hedge Fund, the source and publisher fields will be the same.
  • The volume field refers to a 24h cumulative volume in the quote asset. Our SDK automatically rebases it to be denominated by the base asset given its price.
  • In order to run the publish job, you will need to setup a PragmaOnChainClient that will use the Starknet account you have deployed in step 1 and which you manage with starkli.
  • It's highly recommended you use your own RPC if possible, providers such as Nethermind are recommended.
import asyncio
import logging
import os
import time
from typing import List

from pragma_sdk.common.types.pair import Pair
from pragma_sdk.common.types.entry import Entry, SpotEntry, FutureEntry
from pragma_sdk.onchain.client import PragmaOnChainClient


logger = logging.getLogger(__name__)

# You can fetch your data using any strategy or libraries you want
def fetch_entries(pairs: List[Pair], *args, **kwargs) -> List[Entry]:
    entries: List[Entry] = []

    for pair in pairs:
        entries.append(
            SpotEntry(
                timestamp=int(time.time()),
                source="MY_SOURCE",
                publisher="MY_PUBLISHER",
                pair_id=pair.id,
                price=10 * 10 ** pair.decimals(),  # shifted 10 ** decimals
                volume=0,
            )
        )
        entries.append(
            FutureEntry(
                timestamp=int(time.time()),
                source="MY_SOURCE",
                publisher="MY_PUBLISHER",
                pair_id=pair.id,
                price=10 * 10 ** pair.decimals(),  # shifted 10 ** decimals
                expiry_timestamp=1693275381,  # Set to 0 for perpetual contracts
                volume=0,
            )
        )

    return entries


async def publish_all(pairs: List[Pair]):
    # We get the keystore password and address of the account deployed in step 1.
    keystore_password = int(os.environ.get("PUBLISHER_KEYSTORE_PASSWORD"), 0)
    publisher_address = int(os.environ.get("PUBLISHER_ADDRESS"), 0)

    publisher_client = PragmaOnChainClient(
        account_private_key=("/path/to/keystore", keystore_password),
        account_contract_address=publisher_address,
        network=os.environ["NETWORK"],  # ENV var set to `sepolia | mainnet`
    )

    # Use your own custom logic
    _entries = fetch_entries(pairs)
    await publisher_client.publish_many(_entries)

    logger.info("Publishing the following entries:")
    for entry in _entries:
        logger.info(entry, logger=logger)


PAIRS_TO_PUBLISH = [
    Pair.from_tickers("ETH", "USD"),
    Pair.from_tickers("BTC", "USD"),
    Pair.from_tickers("WBTC", "USD"),
    ... # more pairs
]

if __name__ == "__main__":
    asyncio.run(publish_all(PAIRS_TO_PUBLISH))

tip

To use a custom RPC, you will need to set the network constructor argument to your rpc url. In that case it is mandatory that you set the chain_name argument.

    publisher_client = PragmaOnChainClient(
        account_private_key=("/path/to/keystore", keystore_password),
        account_contract_address=publisher_address,
        network="https://my.custom.mainnet.rpc.url",
        chain_name="mainnet"
    )

4. Docker Image​

In this setup, a Python script would fetch data (your custom logic) and then use the Pragma SDK to publish that data, similar to the script above. In order to deploy you can use the pragma-publisher Docker base image. The base image is available on ghcr and comes with the Python and all requirements (including the pragma Python package) installed.

Again, note the .env file in that same which is passed to Docker at run time via the --env-file arg, with PUBLISHER and PUBLISHER_ADDRESS variables set, as well as a PUBLISHER_KEYSTORE_PASSWORD variable (which is not in the repository for obvious reasons).

Alternatively, you can find an example of how to use the SDK in a serverless deployment (e.g. AWS Lambda).

FROM astraly-labs/pragma-sdk/pragma-sdk:2.0.1:latest

COPY fetch-and-publish.py ./fetch-and-publish.py
CMD python fetch-and-publish.py

Then you can build the docker image docker build . -t pragma-publisher. Finally just run it with the provided env file docker run --env-file .env pragma-publisher

Price Pusher​

If you don't have any data but still want to push data onto the network to increase resiliency of the system. You can simply run the price-pusher image. More instructions on this service can be found here