RPC Gateway

A high-performance RPC gateway that provides load balancing and health checking for multiple RPC providers.

Features

• Load balancing across multiple RPC providers
• Health checking with automatic failover
• Support for multiple chains
• Prometheus metrics
• Configurable timeouts and intervals

Configuration

The gateway is configured using a YAML file. Here's an example configuration:

port: 3000 # port for RPC gateway

metrics:
  port: 9010 # port for prometheus metrics, served on /metrics and /

proxies:
  - path: "eth" # directory path for the proxy (e.g. http://localhost:3000/eth)
    timeout: "1s" # timeout for both upstream requests and health checks
    healthChecks:
      interval: "12s" # how often to do healthchecks
      blockDiffThreshold: 2 # how many blocks behind the max block number to taint
    targets:
      - name: "provider1"
        connection:
          http:
            url: "https://provider1.example.com"
      - name: "provider2"
        connection:
          http:
            url: "https://provider2.example.com"

Configuration Parameters

• port: The port on which the RPC gateway will listen
• metrics.port: The port on which Prometheus metrics will be served
• proxies: List of proxy configurations for different chains
  • path: The URL path for this proxy (e.g., "eth" for Ethereum)
  • timeout: How long to wait for both upstream responses and health checks
  • healthChecks: Health check configuration
    • interval: How often to perform health checks
    • blockDiffThreshold: Maximum allowed block difference between providers
  • targets: List of RPC providers
    • name: Provider identifier
    • connection.http.url: Provider's HTTP URL

Health Checking

The gateway performs health checks on each RPC provider:

1. Block number check: Verifies the provider can return the latest block number
2. Gas left check: Verifies the provider can execute eth_call requests

A provider is marked as unhealthy if:

• Any health check fails
• The provider's block number is too far behind other providers
• The provider fails to respond within the configured timeout

A provider is marked as healthy again as soon as it passes a health check.

Metrics

The gateway exposes Prometheus metrics at /metrics:

• rpc_provider_info: Information about each RPC provider
• rpc_provider_status: Current health status of each provider
• rpc_provider_block_number: Latest block number reported by each provider
• rpc_provider_gas_left: Gas left in each provider

Building

go build -o rpc-gateway

Running

./rpc-gateway -config config.yml

License

MIT

sequenceDiagram
Alice->>RPC Gateway: eth_call
loop Healthcheck
    RPC Gateway->>Alchemy: Check health
    RPC Gateway->>Infura: Check health
end
Note right of RPC Gateway: Routes only to healthy targets
loop Configurable Retries
RPC Gateway->>Alchemy: eth_call?
Alchemy-->>RPC Gateway: ERROR
end
Note right of RPC Gateway: RPC Call is rerouted after failing retries
RPC Gateway->>Infura: eth_call?
Infura-->>RPC Gateway: {"result":[...]}
RPC Gateway-->>Alice: {"result":[...]}

Loading

Development

Make sure the test pass

go test -v ./...

To run the app locally

# Set log level (optional, defaults to "warn")
export LOG_LEVEL=debug  # Available levels: debug, info, warn, error

go run . --config example_config.yml