This repository contains backend code for Cow Protocol Services written in Rust.
The orderbook
crate provides the http api through which users (usually through a frontend web application) interact with the order book.
Users can add signed orders to the order book and query the state of their orders.
They can also use the API to estimate fee amounts and limit prices before placing their order.
Solvers also interact with the order book by querying a list of open orders that they can attempt to settle.
The api is documented with openapi. A simple example script that uses the API to place random orders can be found in this repo
The order book service itself uses PostgreSQL as a backend to persist orders. In addition to connecting the http api to the database it also checks order validity based on the block time, trade events, erc20 funding and approval so that solvers can query only valid orders.
Multiple concurrent orderbook
s can run at the same time, allowing the user-facing API to scale horizontally with increased traffic.
The autopilot
crate is responsible for driving the protocol forward.
Concretely, it is responsible for "cutting" new auctions (i.e. determining auction boundaries and which orders are to be included, as well as various parameters important for settlement objective value computation).
The autopilot
connects to the same PostgreSQL database as the orderbook
and uses it to query orders as well as storing the most recent auction and settlement competition.
The solver
crate is responsible for submitting on-chain settlements based on the orders it gets from the order book and other liquidity sources like Balancer or Uniswap pools.
It implements a few settlement strategies directly in Rust:
- Naive Solver: Can match to overlapping opposing orders (e.g. DAI for WETH & WETH for DAI) with one another settling the excess with Uniswap
- Uniswap Baseline: Same path finding as used by the Uniswap frontend (settling orders individually instead of batching them together)
It can also interact with a more advanced, Gnosis internal, closed source solver which tries to settle all orders using the combinatorial optimization formulations described in Multi-Token Batch Auctions with Uniform Clearing Price
There are additional crates that live in the cargo workspace.
alerter
provides a custom alerter binary that looks at the current orderbook and counts metrics for orders that should be solved but aren'tcontract
provides ethcontract-rs based smart contract bindingsdatabase
provides the shared database and storage layer logic shared between theautopilot
andorderbook
driver
an in-development binary that intends to replace thesolver
; it has a slightly different design that allows co-location with external solverse2e
end-to-end testsethrpc
ethrpc client with a few extensionsmodel
provides the serialization model for orders in the order book apinumber
extensions to number types, such as numerical conversions between 256-bit integers, nonzero types and de/serialization implementationsobserve
initialization and helper functions for logging and metricsshared
provides other shared functionality between the solver and order booktestlib
shared helpers for writing unit and end-to-end tests
The CI (check .github/workflows/pull-request.yaml) runs unit tests, e2e tests, clippy
and cargo fmt
cargo test
cargo test -- postgres --test-threads 1 --ignored
Note: Requires postgres database running (see below).
cargo test -p e2e local_node -- --ignored
.
Note: Requires postgres database and local test network with smart contracts deployed (see below).
FORK_URL=<mainnet archive node RPC URL> cargo test -p e2e forked_node -- --ignored
.
Note: Requires postgres database (see below).
cargo clippy --all-features --all-targets -- -D warnings
The tests that require postgres connect to the default database of a locally running postgres instance on the default port. To achieve this, open a new shell and run the command below: Note: The migrations will be applied as well.
docker-compose up
In order to run the e2e
tests you have to have an EVM compatible testnet running locally.
We make use of anvil from the Foundry project to spin up a local testnet.
anvil
supports all the RPC methods we need to run the services and tests.
- Install foundryup.
- Install foundry with
foundryup
. - Run
anvil
with the following configuration:
ANVIL_IP_ADDR=0.0.0.0 anvil \
--gas-price 1 \
--gas-limit 10000000 \
--base-fee 0 \
--balance 1000000 \
--chain-id 1 \
--timestamp 1577836800
Reading the state of the blockchain requires issuing RPC calls to an ethereum node. This can be a testnet you are running locally, some "real" node you have access to or the most convenient thing is to use a third-party service like infura to get access to an ethereum node which we recommend.
After you made a free infura account they offer you "endpoints" for the mainnet and different testnets. We will refer those as node-urls
.
Because services are only run on Mainnet, Görli, Sepolia, and Gnosis Chain you need to select one of those.
Note that the node-url
is sensitive data. The orderbook
and solver
executables allow you to pass it with the --node-url
parameter. This is very convenient for our examples but to minimize the possibility of sharing this information by accident you should consider setting the NODE_URL
environment variable so you don't have to pass the --node-url
argument to the executables.
To avoid confusion during your tests, always double-check that the token and account addresses you use actually correspond to the network of the node-url
you are running the executables with.
To see all supported command line arguments run cargo run --bin autopilot -- --help
.
Run an autopilot
with:
cargo run --bin autopilot -- \
--skip-event-sync true \
--node-url <YOUR_NODE_URL>
--skip-event-sync
will skip some work to speed up the initialization process.
To see all supported command line arguments run cargo run --bin orderbook -- --help
.
Run an orderbook
on localhost:8080
with:
cargo run --bin orderbook -- \
--node-url <YOUR_NODE_URL>
If your node supports trace_callMany
, or you have an additional node with tracing support, consider also specifying --tracing-node-url <YOUR_NODE_URL>
.
This will enable the tracing-based bad token detection.
Note: Current version of the code does not compile under Windows OS. Context and workaround are here.
To see all supported command line arguments run cargo run --bin solver -- --help
.
Run a solver which is connected to an orderbook
at localhost:8080
with:
cargo run -p solver -- \
--solver-account 0xa6DDBD0dE6B310819b49f680F65871beE85f517e \
--transaction-strategy DryRun \
--node-url <YOUR_NODE_URL>
--transaction-strategy DryRun
will make the solver only print the solution but not submit it on-chain. This command is absolutely safe and will not use any funds.
The solver-account
is responsible for signing transactions. Solutions for settlements need to come from an address the settlement contract trusts in order to make the contract actually consider the solution. If we pass a public address, like we do here, the solver only pretends to be used for testing purposes. To actually submit transactions on behalf of a solver account you would have to pass a private key of an account the settlement contract trusts instead. Adding your personal solver account is quite involved and requires you to get in touch with the team, so we are using this public solver address for now.
To make things more interesting and see some real orders you can connect the solver
to our real orderbook
service. There are several orderbooks for production and staging environments on different networks. Find the orderbook-url
corresponding to your node-url
which suits your purposes and connect your solver to it with --orderbook-url <URL>
.
Orderbook URL | Network | Environment |
---|---|---|
https://barn.api.cow.fi/mainnet/api | Mainnet | Staging |
https://api.cow.fi/mainnet/api | Mainnet | Production |
https://barn.api.cow.fi/goerli/api | Görli | Staging |
https://api.cow.fi/goerli/api | Görli | Production |
https://barn.api.cow.fi/sepolia/api | Sepolia | Staging |
https://api.cow.fi/sepolia/api | Sepolia | Production |
https://barn.api.cow.fi/xdai/api | Gnosis Chain | Staging |
https://api.cow.fi/xdai/api | Gnosis Chain | Production |
Always make sure that the solver
and the orderbook
it connects to are configured to use the same network.
To conveniently submit orders checkout the CowSwap frontend and point it to your local instance.