`sharedState`

The sharedState feature enables multiple eRPC instances to share critical state information across a cluster. This is especially useful for horizontal scaling deployments where having a shared view of blockchain state improves efficiency and reduces unnecessary upstream requests.

Key benefits:

Reduced upstream load: Instances share latest and finalized block info, eliminating redundant polling.
Enhanced integrity checks: More accurate integrity checks for operations like eth_getLogs by using shared latest block number.

Config

erpc.yaml

database:
  sharedState:
    # Unique identifier for a group of eRPC instances that should share state
    # Recommended if you have multiple separate eRPC clusters 
    # Default: "erpc-default"
    clusterKey: "my-cluster-1"
    
    # Storage backend configuration
    # Local "memory" is used by default
    connector:
      # Storage driver: memory, redis, postgresql (memory is default)
      driver: redis
      # Redis-specific configuration
      redis:
        addr: "localhost:6379"
        password: ""
        db: 0
        connPoolSize: 10
    
    # Maximum time to wait for shared state operations before falling back to local state
    # Default: 500ms
    # Lower values improve resilience but may cause more divergence between instances
    fallbackTimeout: 500ms
    
    # Time-to-live for distributed locks
    # Default: 10s
    # Should be longer than typical operation time but not so long it blocks operations if an instance fails
    lockTtl: 10s

⚠️

Setting a unique clusterKey is critical if you have multiple eRPC deployments (e.g., different clusters in Kubernetes). This ensures each cluster maintains its own isolated shared state. If not specified, it defaults to "erpc-default".

Recommendation

We recommend using Redis as the shared state connector for production deployments:

erpc.yaml

database:
  sharedState:
    connector:
      driver: redis
      redis:
        addr: "your-redis-host:6379"

Redis is the recommended connector for shared state as it provides fast synchronization between instances. The total storage needed is typically less than 1MB per upstream.

For more information on available connectors and their configuration options, see the Drivers documentation.

EVM Cache Auth