The Compound Protocol is an Ethereum smart contract for supplying or borrowing assets. Through the cToken contracts, accounts on the blockchain supply capital (Ether or ERC-20 tokens) to receive cTokens or borrow assets from the protocol (holding other assets as collateral). The Compound cToken contracts track these balances and algorithmically set interest rates for borrowers.
Before getting started with this repo, please read:
- The Compound Whitepaper, describing how Compound works
- The Compound Protocol Specification, explaining in plain English how the protocol operates
For questions about interacting with Compound, please visit our Discord server.
We detail a few of the core contracts in the Compound protocol.
- CToken, CErc20 and CEther
- The Compound cTokens, which are self-contained borrowing and lending contracts. CToken contains the core logic and CErc20 and CEther add public interfaces for Erc20 tokens and ether, respectively. Each CToken is assigned an interest rate and risk model (see InterestRateModel and Comptroller sections), and allows accounts to *mint* (supply capital), *redeem* (withdraw capital), *borrow* and *repay a borrow*. Each CToken is an ERC-20 compliant token where balances represent ownership of the market.
- The risk model contract, which validates permissible user actions and disallows actions if they do not fit certain risk parameters. For instance, the Comptroller enforces that each borrowing user must maintain a sufficient collateral balance across all cTokens.
- Contracts which define interest rate models. These models algorithmically determine interest rates based on the current utilization of a given market (that is, how much of the supplied assets are liquid versus borrowed).
- Careful Math
- Library for safe math operations.
- Library for tracking error codes and failure conditions.
- Library for handling fixed-point decimal numbers.
- Library for safely handling Erc20 interaction.
- Initial interest rate model, as defined in the Whitepaper. This contract accepts a base rate and slope parameter in its constructor.
git clone https://github.com/compound-finance/compound-protocol cd compound-protocol yarn # or `npm install`
You can then compile and deploy the contracts with:
yarn run deploy
Note: this project does not use truffle migrations. The command above is the best way to deploy contracts. To view the addresses of contracts, please inspect the
networks/development.json file that is produced as an artifact of that command.
After you deploy, as above, you can run a truffle console with the following command:
yarn run console
This command will create a truffle-like build directory and start a truffle console, thus you can then run:
truffle(rinkeby)> cDAI.deployed().then((cdai) => cdai.borrowRatePerBlock.call()) <BN: 7699bf9dd>
You can also specify a network (rinkeby, ropsten, kovan, goerli or mainnet):
yarn run console rinkeby
The Compound Protocol has a simple scenario evaluation tool to test and evaluate scenarios which could occur on the blockchain. This is primarily used for constructing high-level integration tests. The tool also has a REPL to interact with local the Compound Protocol (similar to
yarn run repl > Read CToken cBAT Address Command: Read CToken cBAT Address AddressV<val=0xAD53863b864AE703D31b819d29c14cDA93D7c6a6>
You can read more about the scenario runner in the Scenario Docs on steps for using the repl.
The easiest way to deploy some Erc20 tokens, cTokens and a Comptroller is through scenario scripts.
# run ganache locally script/ganache # or `ganache-cli` # ensure development files don't exist as # new ganache instances invalidate old deployed contracts rm networks/development* # run deployment script yarn run deploy -v
After that, you'll have a full set of contracts deployed locally. Look in
networks/development.json for the addresses for those deployed contracts. You can use the
yarn run console command above to interact with the contracts (or the scenario REPL, if you prefer).
Mocha contract tests are defined under the test directory. To run the tests run:
yarn run test
or with inspection (visit chrome://inspect) and look for a remote target after running:
node --inspect node_modules/truffle-core/cli.js test
Assertions used in our tests are provided by ChaiJS.
There are additional tests under the spec/scenario folder. These are high-level integration tests based on the scenario runner depicted above. The aim of these tests is to be highly literate and have high coverage in the interaction of contracts.
Formal Verification Specs
The Compound Protocol has a number of formal verification specifications, powered by Certora. You can find details in the spec/formal folder. The Certora Verification Language (CVL) files included are specifications, which when with the Certora CLI tool, produce formal proofs (or counter-examples) that the code of a given contract exactly matches that specification.
To run code coverage, run:
scripts/ganache-coverage # run ganache in coverage mode yarn run coverage
To lint the code, run:
yarn run lint
To run in docker:
# Build the docker image docker build -t compound-protocol . # Run a shell to the built image docker run -it compound-protocol /bin/sh
From within a docker shell, you can interact locally with the protocol via ganache and truffle:
> ganache-cli & > yarn run deploy > yarn run console truffle(development)> cDAI.deployed().then((contract) => cdai = contract); truffle(development)> cdai.borrowRatePerBlock.call().then((rate) => rate.toNumber()) 20
For any concerns with the protocol, visit us on Discord to discuss.
© Copyright 2019, Compound Labs, Inc.