gRPC

Erigon provides gRPC APIs that allow users to access blockchain data and services directly through protocol buffer interfaces. These APIs offer high-performance, strongly-typed access to Erigon's internal services and are particularly useful for applications requiring efficient data access or integration with other gRPC-based systems.

The gRPC server can be explicitly enabled using the --grpc flag when running the standalone rpcdaemon binary. This flag is not available on the main erigon binary — internal gRPC services for components like txpool, downloader, and sentry start automatically on the --private.api.addr endpoint and do not require any additional flag.

Performance Considerations

• gRPC APIs provide better performance than JSON-RPC for high-throughput applications
• Direct database access via KV interface offers the fastest data retrieval
• Shared memory access (when running locally) provides optimal performance

Data Format and Buckets

Database bucket names and their formats are documented in db/kv/tables.go. Understanding these structures is essential for effective use of the KV interface.

Network Access

• gRPC services can be accessed over the network when properly configured
• TLS encryption is recommended for production deployments
• Rate limiting can be configured via --private.api.ratelimit flag

Integration Libraries

Erigon provides Go, Rust, and C++ implementations of the RoKV (read-only key-value) interface for easy integration with applications.

Availability

• gRPC services are available when enabled with the --grpc flag on the standalone rpcdaemon binary
• Default listening address is configurable via --grpc.addr and --grpc.port
• Services require the main Erigon node to be running and accessible

For more information, visit the Erigon Interfaces GitHub repository.

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KV (Key-Value) Interface

The KV interface provides low-level database access methods for reading blockchain data directly from Erigon's MDBX database.

Interface Definition

The KV interface is defined in the remote protobuf specification and provides methods for:

• Opening read-only transactions
• Reading data by key ranges
• Iterating over database buckets
• Accessing historical state data

Example Usage

# Connect to gRPC endpoint
grpcurl -plaintext localhost:9090 remote.KV/Version

Available Methods

Method	Description
Version	Returns the KV service API version
Tx	Opens a read-only transaction for data access
StateChanges	Streams state changes for a block range
Snapshots	Returns information about available snapshots

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ETHBACKEND Interface

The ETHBACKEND interface provides access to Ethereum-specific backend services including block data, transaction information, and network status.

Available Services

Service	Description
Etherbase	Returns the coinbase address
NetVersion	Returns the network ID
NetPeerCount	Returns the number of connected peers
ProtocolVersion	Returns the Ethereum protocol version
ClientVersion	Returns the client version string
Subscribe	Subscribes to blockchain events
NodeInfo	Returns node information
Peers	Returns information about connected peers
AddPeer	Adds a peer to the node
PendingBlock	Returns the pending block
BorEvent	Returns Bor-specific events (Polygon networks only)

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TxPool Interface

The TxPool interface provides access to transaction pool operations and status information.

Available Methods

Method	Description
Version	Returns the TxPool service version
FindUnknownHashes	Finds unknown transaction hashes
GetTransactions	Retrieves transactions from the pool
All	Returns all transactions in the pool
PendingAdd	Adds transactions to pending pool
PendingRemove	Removes transactions from pending pool
OnAdd	Subscribes to transaction addition events
Mining	Returns mining-related transaction data
NonceFromAddress	Gets the next nonce for an address

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Downloader Interface

The Downloader interface provides access to snapshot downloading and torrent management functionality.

Available Methods

Method	Description
Add	Adds files to download queue
Delete	Removes files from download queue
Completed	Checks if downloads are completed
SetLogPrefix	Sets logging prefix for downloader

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Polygon Bridge Backend gRPC API

These gRPC APIs are specifically designed for Polygon's Bor consensus mechanism and are only active when running Erigon with Polygon network configuration. The services provide essential functionality for bridge event processing and validator management required by the Polygon network architecture.

Bridge Backend Methods

Version Method:

• Version() - Returns the service version number.

Transaction Lookup:

• BorTxnLookup(BorTxnLookupRequest) - Looks up Bor transaction information by hash.

Event Retrieval:

• BorEvents(BorEventsRequest) - Retrieves bridge events for a specific block.

Bridge Backend Implementation

The server implementation is found in polygon/bridge/server.go where the BackendServer struct implements the BridgeBackendServer interface:

• The BorTxnLookup method implementation shows how it handles transaction lookups.
• The BorEvents method retrieves bridge events for a given block.

Heimdall Backend gRPC API

The Heimdall Backend service provides APIs for validator and consensus-related functionality.

Heimdall Backend Methods

Version Method:

• Version() - Returns the service version number.

Producer Information:

• Producers(BorProducersRequest) - Retrieves validator/producer information for a specific block.

Service Integration

Both services are integrated into the main Ethereum backend when Bor consensus is configured. In the main backend initialization, you can see how these services are set up.

The Bridge and Heimdall services are created with their respective RPC servers.

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Configuration and Security

TLS Configuration

Erigon supports TLS encryption for gRPC connections using certificate files:

./build/bin/rpcdaemon --grpc --tls.cert=/path/to/cert.pem --tls.key=/path/to/key.pem --tls.cacert=/path/to/ca.pem

Health Checks

gRPC health checks can be enabled to monitor service availability:

./build/bin/rpcdaemon --grpc --grpc.healthcheck

Connection Examples

Go Client Example

conn, err := grpc.Dial("localhost:9090", grpc.WithInsecure())
if err != nil {
    log.Fatal(err)
}
defer conn.Close()

client := remote.NewKVClient(conn)
// Use client for database operations

Direct Database Access

The gRPC interface allows reading Erigon's database while the node is running, sharing the same OS-level PageCache for optimal performance.