Gas payments MVP

[serejke]

Overview

We are currently considering different approaches for managing the relationship between the Outbox and gas payments. After thorough examination, it seems that a very simple Minimum Viable Product (MVP) solution is emerging that could address the issue without requiring on-chain quoting/rates.

Description

The proposed MVP solution involves the following steps:

• The Outbox remains independent of gas payments as it currently is, meaning that there won't be any changes to its behavior regarding transaction fees.
• We do not implement on-chain quoting or rates.
• A DApp can dispatch a message via Outbox at any time by paying the normal transaction fee.
• The DApp knows the dispatched messageId and the relayer's address.
• The DApp posts a UTXO with Datum = messageId and ADA on the relayer's address. Note that anyone can post such a UTXO and even pay for others' messages.
• The amount of ADA that needs to be paid is calculated off-chain.
• The relayer listens to UTXO on its address.
  When the relayer is ready to relay a message, it performs off-chain fee quoting (dependent on the ADA-to-ETH current ratio), and decides whether it wants to relay the message or not. If not, the DApp needs to pay more.

Outcomes

This simple MVP solution aims to streamline the process of fee payments and make them more flexible, taking into account the changing ADA-to-ETH ratio and allowing for off-chain calculations. The relayers will have more autonomy in deciding whether or not to relay a message based on the paid fee.

Subtasks

• Gas payments MVP: indexer of message payments #32
• Gas payments MVP: integrate payments into relayer #54

[hai-kreate]

Current status:

• Payment tx: https://github.com/tvl-labs/hyperlane-cardano/blob/main/src/offchain/tx/payOutboundRelayer.ts
• Indexer: https://github.com/tvl-labs/hyperlane-cardano/blob/main/src/offchain/indexer/getOutboundGasPayment.ts
• RPC endpoint:

  hyperlane-cardano/src/rpc/index.ts

  Lines 224 to 237 in 5ff45e7

  	app.post(
  	"/api/outbox/get-message-gas-payment",
  	async function (
  	req: Request<GetOutboundGasPaymentRequestBody>,
  	res: Response<GetOutboundGasPaymentResponseBody>,
  	_
  	) {
  	const totalGasADA = await getOutboundGasPayment.getOutboundGasPayment(
  	new helios.Address(req.body.relayerAddress),
  	new helios.ByteArray(req.body.messageId)
  	);
  	res.status(200).json({ totalGasADA });
  	}
  	);

• Test: https://github.com/tvl-labs/hyperlane-cardano/blob/main/src/test/testOutbox.ts