Configuration

Hierarchical configuration system for CoW Protocol Services including CLI, environment variables, TOML files, and runtime adjustments

Configuration

CoW Protocol Services employ a hierarchical configuration system supporting command-line arguments, environment variables, TOML files, and runtime adjustments. All services include --help documentation.

Configuration Priority

Settings follow this precedence (highest to lowest):

1. Command-line arguments
2. Environment variables
3. Configuration file values
4. Default values

Key Configuration Areas

Database Connectivity

Services use PostgreSQL with sqlx connection pooling. The default pool size is 10 connections, adjustable via --db-max-connections.

Connection strings follow PostgreSQL format:

postgresql://[user[:password]@][host][:port][/database]

Network Settings

Core parameters include:

• Primary RPC: --node-url
• Simulation RPC: --simulation-node-url (optional)
• Chain identification: --chain-id
• Block timing: --network-block-interval

Contract addresses can be overridden for settlement, balances, and signatures components.

Gas Estimation

Services support multiple estimators (Native, Web3, EthGasStation, GasNow) with configurable price caps.

It is recommended to include “Native” and “Web3” for compatibility across all EVM chains.

Logging System

The system uses tracing-subscriber with flexible EnvFilter syntax:

target[span{field=value}]=level

Output Formats

• Human-readable (default) - For development
• Structured JSON - Preferred for production with log aggregation systems

Runtime Adjustments

Connect to UNIX sockets to modify log filtering without restart:

/tmp/log_filter_override_<program_name>_<pid>.sock

TOML Configuration

Complex settings use TOML files for services like Driver, Autopilot, and Orderbook, supporting structured configuration for solvers, contracts, liquidity, and fee policies.

Network-Specific Presets

Network	Chain ID	Block Interval
Mainnet	1	12s
Gnosis	100	5s
Arbitrum	42161	250ms
Base	8453	2s

Performance Optimization

Connection pool recommendations vary by service role:

Service	Recommended Pool Size
Orderbook	50
Autopilot	20
Driver	15

Multiple RPC endpoints enable redundancy and separate simulation capabilities.

Best Practices

• Store sensitive credentials in environment variables only
• Enable JSON logging for production deployments
• Use appropriate log levels (info/warn for production, debug/trace for troubleshooting)
• Leverage runtime filtering for production debugging without restarts
• Explicitly set chain IDs to catch configuration errors early