OnChainLiquidator #642

scott-silver · 2022-12-29T17:32:36Z

This PR rewrites the Liquidator.sol contract (renamed to OnChainLiquidator in order to distinguish from the DEX-aggregated Liquidator in #632).

The primary changes to the contract are:

support for Curve exchange
support for Balancer exchange
Comet is passed in as an argument, so the one contract can work for multiple deployments on the same chain
PoolConfigs and liquidation thresholds are passed as arguments, so you can retry different size swaps and swaps via different exchanges without changing on-chain storage

Additionally, the Liquidation Bot background process now implements a liquidation process with backoff/fallback logic.

Previously, a failure to clear any asset would cause the entire liquidation process to fail. Now, we do the following:

Attempt to clear all purchaseable amounts of all assets
If that fails, then fall back to a more incremental process:
1. absorb any liquidatable assets
2. for each asset, attempt to buy/swap a known reasonable amount of the asset.
3. if that fails, attempt to buy/swap 50% of that known reasonable amount
4. if that fails, attempt to buy/swap 10% of that known reasonable amount

This change should be sufficient for us to launch the mainnet/WETH market (the OnChainLiquidator can clear large amounts of both cbETH and wstETH).

Once this is merged, we can revisit #632 and replace the initial attempt to purchase all available assets via the OnChainLiquidator with an attempt purchase all available assets via the DexAggregatedLiquidator.

TODO

lint
update remaining LiquidationBotScenario scenarios
delete OnChainLiquidationBotScenario.ts
move exchange interfaces into separate contract file
~~add swapWithMax forge tests~~ will do as follow-up

deployments/mainnet/weth/configuration.json

contracts/liquidator/OnChainLiquidator.sol

forge/test/OnChainLiquidator.t.sol

scenario/LiquidationBotScenario.ts

scenario/OnChainLiquidatorScenario.ts

scripts/liquidation_bot/liquidateUnderwaterBorrowers.ts

contracts/liquidator/OnChainLiquidator.sol

scenario/OnChainLiquidatorScenario.ts

jflatow

looking great 💪

scenario/OnChainLiquidatorScenario.ts

contracts/liquidator/OnChainLiquidator.sol

kevincheng96

Looks great so far!

contracts/liquidator/OnChainLiquidator.sol

kevincheng96 · 2022-12-29T23:03:33Z

contracts/liquidator/OnChainLiquidator.sol

+    ) external returns (uint256[] memory amounts);
+}
+
+// Balancer Interfaces


Just out of interest, which of the assets we support are most liquid on Balancer?

Balancer is good for swapping wstETH to WETH.

Curve is also good, but it only has a decent pool for stETH -> ETH so you have to unwrap wstETH and then wrap the ETH to WETH

contracts/liquidator/OnChainLiquidator.sol

kevincheng96 · 2022-12-29T23:13:38Z

contracts/liquidator/OnChainLiquidator.sol

+
+        TransferHelper.safeApprove(swapToken, address(curvePool), swapAmount);
+
+        uint amountOut = IStableSwap(curvePool).exchange(


What's the output token? I assume it's the baseToken, but I don't see that being specified anywhere.

It's swapping directly to ETH. calling find_pool_for_coins with nullAddress as the second argument looks for a pool from the first token to ETH.

made a note on the appropriate line, but this function is currently written assuming that you're swapping directly to ETH, which probably won't always be true. will update

kevincheng96 · 2022-12-29T23:14:40Z

contracts/liquidator/vendor/@uniswap/v3-periphery/contracts/base/PeripheryPayments.sol

-    receive() external payable {
-        require(msg.sender == WETH9, 'Not WETH9');
-    }


Is some other contract sending ETH now?

yep, Curve has pools that swap directly to ETH, so you receive ETH as part of the swap

contracts/liquidator/OnChainLiquidator.sol

scripts/liquidation_bot/liquidateUnderwaterBorrowers.ts

.github/workflows/run-forge-tests.yaml

test/liquidation/liquidation-bot-script.ts

jflatow

Huge effort, great job spearheading this 🥈 🥇 🏆 💪 💧

Update the reference liquidator to source from more pools and generally be more robust

kevincheng96 · 2023-01-10T05:05:21Z

💯 Great work on this! Sorry for the late review, was focused on some other stuff last week.

* Mainnet ETH Deployment * Update Github Actions to include mainnet-eth * ETH-base bulker scenario * WstETHPriceFeed + tests (#600) * Non-ETH and ETH bulker scenarios (all actions in one txn) * Mainnet WETH Bulker (#611) * Add a supply cap constraint and set initial caps to 0 for cWETHv3 * Update the collateral params based on Gauntlet recommendations (#628) https://hackmd.io/wncIvkFTReWUe2AMMK2ezA?view * Price feeds for WETH deployment + Bulker changes for OZ audit (#625) This PR implements and modifies price feeds to support the upcoming WETH deployment. The favored plan so far is to use ETH-denominated price feeds as opposed to USD price feeds, but stick with using 8 decimals for prices to avoid having to change the `Comet` and `Configurator` implementations. This would require: - A new wrapper price feed (`ScalingPriceFeed.sol`) that scales prices up or down to 8 decimals - A new `ConstantPriceFeed` that always returns 1e8 for the `WETH` base asset, since should always hold a 1:1 value with ETH - Modifications to the `WstETHPriceFeed` to return prices in terms of ETH instead of USD This is an alternative approach to #626, which is a more complex change but could be a better long-term solution. *Note: This PR also now contains the changes from #634 and #635, which address some suggestions made by OZ for their audit of `WstETHPriceFeed` and `Bulker`.* * Refactor deploy to support second markets (#639) * Refactor deploy to support second markets * Add a fromDep to deployment manager which can be used for sharing dependency contracts from another deployment * Always attempt to initialize storage if needed, and not necessarily as gov * Always deploy an initial implementation contract instead of using the factory marker * Only take gov admin actions if we own the cometAdmin * Expose the primitives necessary for a proposal to configurate later, if/when admin cannot * Add an env flag for migration constraint to skip non-migration scenarios * Defer reading current config in modern constraint (bugfix) * Add recipient to token sourcing blacklist * WETH deployment audit changes (#641) These are changes in response to the WETH deployment [audit](https://gist.github.com/andresbach/a01686b1ef8bdf51d46046f2cfc93307) conducted by OZ: - **L01 - Lack of input validation** - We originally avoided zero address checks because there are a vast amount of accidental addresses that can be set here and checking for a specific one seems unnecessary. However, we have reconsidered that position after seeing the reasons for including a zero address check listed in this [post](https://forum.openzeppelin.com/t/removing-address-0x0-checks-from-openzeppelin-contracts/2222/13). - **L02 - Improper implementation of Chainlink AggregatorV3Interface** - We updated the hard-coded return values for `roundId` and `answeredInRound` to be 1 to comply with the Chainlink specification. - **L04 - Incomplete/confusing documentation** - We updated the documentation based on the provided suggestions. Our full audit responses are [here](https://docs.google.com/document/d/1A8TrUdTtD7DXr1U5HOqSS1Xl81rjBZdlDC7LS4No4Bw). * Spider USDC deployment before calling `fromDep` (#644) We need to spider the `USDC` deployment before calling `fromDep` on it so all the aliases are populated in the cache. Otherwise, `fromDep` may try to import an `undefined` contract. There are many approaches to this and this PR takes the simplest approach of spidering in the deploy script. Another approach could be to handle the spidering directly in `fromDep`. * Convert from scientific notation to bigint in configuration (#643) This PR adds a new `ScientificNotation` string type to `NetworkConfiguration` that is required for certain fields (e.g. `supplyCap`, `baseMinForRewards`). The configuration parser will safely convert these values into bigints without losing precision; with one caveat, scientific notations that use decimals in the coefficient still run the risk of precision loss because those are converted directly to javascript numbers. * Explicit supply cap constraint for failing bulker scen (#648) * Add tracking index bounds unit tests for WETH (#645) * Update params and rate model final numbers for deployment * OnChainLiquidator (#642) Update the reference liquidator to source from more pools and generally be more robust * Fix fromDep to spider the dependency and load the contract from it (#652) * bump targetReserves in LiquidationBotScenarios (#653) * delete CURVE_REGISTRY (#654) * OnChainLiquidator, not Liquidator (#655) * Combined model based on Gauntlet's first and second recommendations (#656) * Wrap and unwrap native token as base asset in Bulker (#659) * Add tests for supply native token; clean up * Change supplyStETH to use stETH amount instead of wstETH amount; add scenarios * Tweak comments * Supplying uint256.max collateral reverts in WETH deposit not Comet * Modified deployment roots from GitHub Actions * Proposal to enable cWETHv3 market (#608) * Proposal to enable cWETHv3 market * Modify proposal to add rewards * Update the supply caps based on Gauntlet recommendations (#629) https://hackmd.io/wncIvkFTReWUe2AMMK2ezA?view * Refactor proposal to make market live (#640) * If there are migrations, don't run the non-migrations This allows a proposal branch to pass CI if the migration is required and is generally the intention for migration branches. However an env var is still supported to override and force running the non-migration, too. * Final changes to supply caps; proposal text; WETH transfer amt (#662) Also copy bulker to usdc roots and fix scen test fixes * Deploy cWETHv3 to Goerli (#646) This PR adds a new `goerli-weth` base and deploy script for the Goerli cWETHv3 deploy. The deploy script is very similar to the mainnet cWETHv3 script. The main differences are: - Deploying price feeds for stETH / ETH and cbETH / ETH - Pulling in extra testnet/cross-chain contracts such as `fauceteer` and `fxRoot` using `fromDep` - Cloning over `cbETH` from mainnet - Minting `cbETH` to `fauceteer` * Modified migration from GitHub Actions Co-authored-by: Kevin Cheng <kevincheng96@hotmail.com> Co-authored-by: scott-silver <scott@compound.finance> Co-authored-by: GitHub Actions Bot <>

scott-silver requested review from jflatow and kevincheng96 December 29, 2022 17:32