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An efficient money market protocol for Ethereum and compatible chains (aka Compound III, Compound v3).


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Compound Comet

Getting started

  1. Clone the repo
  2. Run yarn install

Env variables

The following env variables are used in the repo. One way to set up these env variables is to create a .env in the root directory of this repo.

Required env variables:


Optional env variables:

ETH_PK=<eth-key>             # takes precedence over MNEMONIC

Git hooks

The repo's Git hooks are defined the .githooks/ directory.

You can enable them by running:

# requires git version 2.9 or greater
git config core.hooksPath .githooks

You can skip pre-commit checks with the -n flag:

git commit -n -m "commit without running pre-commit hook"

Multi-chain support

Currently, Avalanche mainnet and testnet (fuji) are supported. This means that deployment scripts, scenarios, and spider all work for Avalanche.

To use this project with other chains, the block explorer API key for your target chain must be set in .env (e.g. SNOWTRACE_KEY for Avalanche).

An example deployment command looks like:

yarn hardhat deploy --network fuji --deployment usdc

Comet protocol contracts

Comet.sol - Contract that inherits CometMainInterface.sol and is the implementation for most of Comet's core functionalities. A small set of functions that do not fit within this contract are implemented in CometExt.sol instead, which Comet DELEGATECALLs to for unrecognized function signatures.

CometExt.sol - Contract that inherits CometExtInterface.sol and is the implementation for extra functions that do not fit within Comet.sol, such as approve.

CometInterface.sol - Abstract contract that inherits CometMainInterface.sol and CometExtInterface.sol. This interface contains all the functions and events for Comet.sol and CometExt.sol and is ERC-20 compatible.

CometMainInterface.sol - Abstract contract that inherits CometCore.sol and contains all the functions and events for Comet.sol.

CometExtInterface.sol - Abstract contract that inherits CometCore.sol and contains all the functions and events for CometExt.sol.

CometCore.sol - Abstract contract that inherits CometStorage.sol, CometConfiguration.sol, and CometMath.sol. This contracts contains functions and constants that are shared between Comet.sol and CometExt.sol.

CometStorage.sol - Contract that defines the storage variables used for the Comet protocol.

CometConfiguration.sol - Contract that defines the configuration structs passed into the constructors for Comet.sol and CometExt.sol.

CometMath.sol - Contract that defines math functions that are used throughout the Comet codebase.

CometFactory.sol - Contract that inherits CometConfiguration.sol and is used to deploy new versions of Comet.sol. This contract will mainly be called by the Configurator during the governance upgrade process.

Configurator contracts

Configurator.sol - Contract that inherits ConfiguratorStorage.sol. This contract manages Comet's configurations and deploys new implementations of Comet.

ConfiguratorStorage.sol - Contract that inherits CometConfiguration.sol and defines the storage variables for Configurator.sol.

Supplementary contracts

Bulker.sol - Contract that allows multiple Comet functions to be called in a single transaction.

CometRewards.sol - Contract that allows Comet users to claim rewards based on their protocol participation.

Vendor contracts

Third-party contracts (e.g. OZ proxies) live under contracts/vendor.

There are currently two Comet-related contracts that extend directly from the vendor contracts. The contracts are:

ConfiguratorProxy.sol - This contract inherits OZ's TransparentUpgradeableProxy.sol. We override the _beforeFallback function so that the proxy's admin can directly call the implementation. We only need this feature for the Configurator's proxy.

CometProxyAdmin.sol - This contract inherits OZ's ProxyAdmin.sol. We created a new function called deployAndUpgradeTo, which calls Configurator.deploy(0xCometProxy) and upgrades Comet proxy's implementation to this newly deployed Comet contract. This function is needed so we can pass the address of the new Comet to the Proxy.upgrade() call in one transaction.


Look at the scripts section inside package.json to find all commands.

Build contracts

Compiles contracts.

yarn build

Lint contracts

Contract linting is done via Solhint.

yarn lint-contracts
yarn lint-contracts:fix // will attempt to automatically fix errors

Solhint configuration is saved in .solhint.json.

Run tests

Runs all tests in the test directory.

yarn test

Run tests with coverage tool

Runs all tests while also evaluating code coverage.

yarn test:coverage

The coverage report will be saved in the coverage directory.

Run tests with gas profiler

Set up the following env variables:

  • REPORT_GAS=true
  • COINMARKETCAP_API_KEY=your_coinmarket_api_key optional, only if you want to see cost in USD

Run forge tests

Experimental support for foundry has been added, so assuming forge is installed:

forge test

See the GitHub workflow for an example.

Deploy contracts

Deploys contracts to a specified chain using a deployment script.

yarn hardhat deploy --network mainnet --deployment usdc


Spider is a tool for programmatically fetching all protocol-related contracts from a desired network. Contracts are pulled in starting from the root set of contracts defined in roots.json. Then, it discovers and pulls in the web of related contracts (relations defined in relations.json), recursively iterating over new contracts until there are no more contracts left to discover. With spider, we can generate the comprehensive list of relevant contracts for each deployment directly from the blockchain without having to manually maintain all the addresses.

Once run locally, the spider task will generate a list of all the relevant contracts for a specific deployment in a file called aliases.json.

Note: Spider relies on the Etherscan API to pull in contract-related info such as ABIs.

Run spider task

Note: Make sure $ETHERSCAN_KEY is set as an env variable.

npx hardhat spider --network mainnet --deployment usdc

Delete spider artifacts

You can delete all spider artifacts using the --clean flag:

npx hardhat spider --clean

Spider configs

The spider script uses configuration from two files to start its crawl:

  • roots.json
  • relations.json

Both these contracts are committed to the repo under deployments/<network>/<deployment>/<file>.json. The roots.json config contains the address of the root contract for spider to start crawling from. The relations.json config defines all the different relationships and rules that spider will follow when crawling. The following section will go over in detail the set of rules defined in relations.json.

Defining relations

Currently, these are the 3 types of rules in relations.json that can be defined for a contract:

  1. Alias - A rule to derive the key that is assigned to this contract in pointers.json. If this rule is not provided, the contract name will be used as the alias instead. This rule has two special characters: @ and +. @ followed by a function name is used to read a value from that contract's function. + is used as a delimiter. Example: @symbol+Delegator will equate to cDaiDelegator for cDai's delegator contract.
  2. Relations - The names of the contract's functions to call to fetch dependent contracts.
  3. Implementation - The name of the contract's function to call to grab its implementation address. This should only be defined for proxy contracts.


Scenarios are high-level property and ad-hoc tests for the Comet protocol. To run and check scenarios:

npx hardhat scenario

For more information, see


Migrations are used to make proposals to governance, for changes to the live protocol. A migration script has two parts: prepare and enact. The prepare step can perform necessary preparation of artifacts for the enact step, which is where the proposal gets made.

Migrations integrate with scenarios, so that changes are automatically tested against the entire scenario suite, with and without the proposal. In fact, all combinations of open migrations are checked against the protocol, to ensure safety against any execution order by governance. The same script that is used for testing can then be executed for real through the GitHub UI.

Once a proposal that's been made through a pull request has been executed by governance, the pull request should be merged into the main branch. The PR should include any necessary tests, which will remain in the repository. The migration script itself can be deleted in a separate commit, after the PR has been merged and recorded on the main branch, for good hygiene. It's important to remove migrations once they've been executed, to avoid exploding the cost of running scenarios beyond what's necessary for testing.

For more information, seee

Deploying to testnets

Each deployment of Comet should have an associated directory inside of deployments in the repository. Deployments are stored per network, for instance deployments/mainnet/usdc/.

To start a new deployment, create the directory with a deploy.ts script and a configuration.json file (both probably copied initially from another deployment). When copying files from other directories, migrations may safely be ignored, as they are meant only for migrating the state of an existing deployment, not starting fresh deployments. New deployments and changes to them are also hypothetically tested with scenarios, like migrations are. These simulations are extremely useful for testing deployments before actually creating them.

Deploy Workflow

  1. Create the deployment script and configuration file, and test locally
  2. Open a PR containing the new deployment directory files
  3. Trigger the deploy-market workflow action through the GitHub UI
  4. Inspect the new roots.json which the workflow automatically commited to your PR
  5. Start using the new protocol deployment and/or create further migrations to modify it
Deploy Script Gotchas and Tips
  • If the deploy script is for a new market on a chain with an existing market, make sure to call 'setFactory(address,address)' in the initialization migration script. (TODO: Scenarios will fail prior to running the migration script because the factory will not be set during deployment, will need to figure out a better way)
Verifying Deployments

Source code verification is a relatively important part of deployments currently. The 'spider' tool we use to crawl relevant addresses from the root addresses by default relies on pulling verified contract ABIs. Verification happens normally as part of the deploy command-line task (the same command triggered by the deploy-market workflow). Since deployments are idempotent by default, the deploy command can also be used to just verify the existing contracts (an explicit way to do this is via the --no-deploy flag). When all contracts are already deployed, the only actions performed will be to verify the contracts remaining in the verification cache. The script always attempts to verify the Comet implementation contract, since this is deployed via a factory and the status is relatively unknown to it.

The --simulate flag can be used when running deploy to check what the effect of running a deploy would actually be, including verification. This can also be used together with --overwrite, to produce the verification artifacts locally, which can then be used to run full verification for real.

Other considerations

Make sure that the deploying address has a sufficient amount of the chain's native asset (i.e. 2 ETH for Goerli, 2 AVAX for Fuji)

Clone Multisig

The clone-multisig script can be used to clone the multisig and its configuration from an existing deployment, e.g.:

DST_NETWORK=optimism npx hardhat run scripts/clone-multisig.ts

Liquidation Bot

This repo includes a contract (Liquidator.sol) that will absorb an underwater position, purchase the absorbed collateral, and then attempt to sell it on Uniswap for a profit.

To run the bot, you'll need the address of a deployed version of the Liquidator contract (or you can deploy a new instance of it yourself):

LIQUIDATOR_ADDRESS="0xABC..." DEPLOYMENT="usdc" yarn liquidation-bot --network goerli

Initiating transactions this way via the public mempool will almost certainly get frontrun, but you might be able to use flashbots to mask your transactions from frontrunners.


An efficient money market protocol for Ethereum and compatible chains (aka Compound III, Compound v3).