Feegrant: Is it possible to implement the content of a sponsored-transactions (user A's fee is paid by user B)?

[99Kies]

Is it possible to implement the content of a sponsored-transactions on cosmwasm (user A's fee is paid by user B)

[webmaster128]

There is a fee payer in transactions and a feegrant module in Cosmos SDK. I think this is what you are looking for. But this is happening on the Cosmos SDK level and is not CosmWasm specific.

[vishrutsingh]

Fee grant support was discussed in #1200 but was there any further discussion on this topic? Can't find any implementation in the code.
This could be useful to have if one has to test a contract on mainnet and has insufficient/low funds to begin with.

[webmaster128]

Here is a team that is issuing grants as a contract (i.e. contract is grantee):
https://github.com/astroport-fi/astroport-core/blob/52af83eab04c620ac40019f7cc9cee433d0c601e/contracts/periphery/fee_granter/src/contract.rs#L120-L181

It's great this works but is not very convenient yet. E.g. the GRANTS need to be tracked separatly instead of being queried from chain.

[99Kies]

@webmaster128

Can the --allowed-messages in this feegrant be set to the specified contract address?

I want dapp user to be able to use money from my account for gas fee when they can use my contract.

[webmaster128]

@99Kies can you open an issue for that in wasmd (and link it here)? Alex should be able to help over there.

[webmaster128]

I want dapp user to be able to use money from my account for gas fee when they can use my contract.

Other devs achieve something similar by allowing the users to spend the contract's funds. In this case the contract needs to create the grant itself. Not necessarily easier but seems to be possible.

[99Kies]

https://github.com/astroport-fi/astroport-core/blob/52af83eab04c620ac40019f7cc9cee433d0c601e/contracts/periphery/fee_granter/src/contract.rs#L120-L181

@webmaster128 I see this function. It's actually executing wasmd tx feegrant grantContractAddress granteeContractAddress.

By this way can user A call the methods of grantee Contract without consuming the handling fee?

[99Kies]

@webmaster128 I tried this and specifying grantee as the contract address doesn't work. Since it's still the user who is initiating the transaction, the fee is still paid by the user.