A simple example on how to use Rockside with Gnosis Safe Wallet is available here.
Refund with DAI
Rockside enables a Gnosis Safe to refund the relayer with DAI.
In order to enable the refund in DAI, when calling the execTransaction on the gnosis, you need to specify parameters gasToken to 0x6b175474e89094c44da98b954eedeac495271d0f and gasPrice to the amount of DAI for each unit of gas.
Rockside checks that the amount of DAI is equal or superior to the gas price (in ether) multiplied by the ether value in USD (retrieved via the Coingecko API).
For example, if the gas price is 10 GWEI and the ether value is $400, the the gasPrice must be set to a value equal or superior to 0.00000001*400 . Here 0.00000001 is 10 GWEI represented in ETH.