> ## Documentation Index
> Fetch the complete documentation index at: https://docs.cow.bleu.builders/llms.txt
> Use this file to discover all available pages before exploring further.

# 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