The RngWitnet.sol suite of contracts is an extension of the RNGInterface contract provided by PoolTogether. Its goal is to fetch a single random number to complete a prize draw. To achieve this it leverages the Witnet Randomness Oracle. The cost for the RNG request is paid from the balance of the RngWitnet contract.
Following command line examples will help you setup the RngWitnet suite on the Goerli network. Because Brownie does not allow passing parameters to its scripts, I use a config.json file to pass them.
First deploy a WitnetRequestRandomness instance (based on WitnetRequestMalleableBase from guidiaz). If an instance already exists, the address of this instance can be specified in config.json and the RngWitnet contract will create a clone which is significantly cheaper. Once deployed, make sure to add the isntance's address to the config.json file.
brownie run deploy_witnet_request_randomness --network goerli-alchemy
After deploying a WitnetRequestRandomness instance or specifying a previously deployed instance, you can deploy the RngWitnet instance. Note that an instance of the WitnetRequestBoard needs to be configured in config.json and its address varies per network. For testing purposes (see below), the main function allows passing the address of a WitnetRequestRandomness instance, but this is irrelevant when actually deploying the contracts.
brownie run deploy_rng_witnet --network goerli-alchemy
Set the maximum amount of ETH that can be spent on a single randomness request. This fee can be configured in config.json.
brownie run set_max_fee.py --network goerli-alchemy
Add one or more addresses that are allowed to fetch random numbers. These can be configured in config.json.
brownie run add_allowed_requester.py --network goerli-alchemy
A set of tests has been included to test both the RngWitnet contract and the WitnetRequestRandomness contract. They can be run through the following command:
brownie test --disable-warnings
Note the usage of --disable-warnings to prevent eth-utils warnings polluting the output. Remove the flag if you want to see them.
All required contracts have been deployed on following networks.
| Contract | Address |
|---|---|
| WitnetRequestRandomness | 0xb9C7D8dcEca7C830Bd0feF36cb9182822e165209 |
| RngWitnet | 0x0dca49d777fd938ee476d400d0b477222bd10aa9 |
| Contract | Address |
|---|---|
| WitnetRequestRandomness | 0x292db823328dcd6e486fd5ac423da4327cad1130 |
| RngWitnet | 0xdd9f0fa196931351b3bef9ab9458cacd349e63c2 |
Thanks to all the people who reviewed the initial version of the contracts, especially to guidiaz for the thorough review and input.