GetBlockHash

GetBlockHash returns the hash of the block in the best blockchain at the given height.

Source: chainrpc/chainkit.proto

gRPC

rpc GetBlockHash (GetBlockHashRequest) returns (GetBlockHashResponse);

REST

HTTP Method	Path
GET	/v2/chainkit/blockhash

Code Samples

gRPC

Javascript

const fs = require('fs');
const grpc = require('@grpc/grpc-js');
const protoLoader = require('@grpc/proto-loader');

const GRPC_HOST = 'localhost:10009'
const MACAROON_PATH = 'LND_DIR/data/chain/bitcoin/regtest/admin.macaroon'
const TLS_PATH = 'LND_DIR/tls.cert'

const loaderOptions = {
  keepCase: true,
  longs: String,
  enums: String,
  defaults: true,
  oneofs: true,
};
const packageDefinition = protoLoader.loadSync(['lightning.proto', 'chainrpc/chainkit.proto'], loaderOptions);
const chainrpc = grpc.loadPackageDefinition(packageDefinition).chainrpc;
process.env.GRPC_SSL_CIPHER_SUITES = 'HIGH+ECDSA';
const tlsCert = fs.readFileSync(TLS_PATH);
const sslCreds = grpc.credentials.createSsl(tlsCert);
const macaroon = fs.readFileSync(MACAROON_PATH).toString('hex');
const macaroonCreds = grpc.credentials.createFromMetadataGenerator(function(args, callback) {
  let metadata = new grpc.Metadata();
  metadata.add('macaroon', macaroon);
  callback(null, metadata);
});
let creds = grpc.credentials.combineChannelCredentials(sslCreds, macaroonCreds);
let client = new chainrpc.ChainKit(GRPC_HOST, creds);
let request = {
  block_height: <int64>,
};
client.getBlockHash(request, function(err, response) {
  console.log(response);
});
// Console output:
//  {
//    "block_hash": <bytes>,
//  }

Python

import codecs, grpc, os
# Generate the following 2 modules by compiling the chainrpc/chainkit.proto with the grpcio-tools.
# See https://github.com/lightningnetwork/lnd/blob/master/docs/grpc/python.md for instructions.
import chainkit_pb2 as chainrpc, chainkit_pb2_grpc as chainkitstub

GRPC_HOST = 'localhost:10009'
MACAROON_PATH = 'LND_DIR/data/chain/bitcoin/regtest/admin.macaroon'
TLS_PATH = 'LND_DIR/tls.cert'

# create macaroon credentials
macaroon = codecs.encode(open(MACAROON_PATH, 'rb').read(), 'hex')
def metadata_callback(context, callback):
  callback([('macaroon', macaroon)], None)
auth_creds = grpc.metadata_call_credentials(metadata_callback)
# create SSL credentials
os.environ['GRPC_SSL_CIPHER_SUITES'] = 'HIGH+ECDSA'
cert = open(TLS_PATH, 'rb').read()
ssl_creds = grpc.ssl_channel_credentials(cert)
# combine macaroon and SSL credentials
combined_creds = grpc.composite_channel_credentials(ssl_creds, auth_creds)
# make the request
channel = grpc.secure_channel(GRPC_HOST, combined_creds)
stub = chainkitstub.ChainKitStub(channel)
request = chainrpc.GetBlockHashRequest(
  block_height=<int64>,
)
response = stub.GetBlockHash(request)
print(response)
# {
#    "block_hash": <bytes>,
# }

REST

Javascript

const fs = require('fs');
const request = require('request');

const REST_HOST = 'localhost:8080'
const MACAROON_PATH = 'LND_DIR/data/chain/bitcoin/regtest/admin.macaroon'

let options = {
  url: `https://${REST_HOST}/v2/chainkit/blockhash`,
  // Work-around for self-signed certificates.
  rejectUnauthorized: false,
  json: true,
  headers: {
    'Grpc-Metadata-macaroon': fs.readFileSync(MACAROON_PATH).toString('hex'),
  },
}
request.get(options, function(error, response, body) {
  console.log(body);
});
// Console output:
//  {
//    "block_hash": <string>, // <bytes> 
//  }

Python

import base64, codecs, json, requests

REST_HOST = 'localhost:8080'
MACAROON_PATH = 'LND_DIR/data/chain/bitcoin/regtest/admin.macaroon'
TLS_PATH = 'LND_DIR/tls.cert'

url = f'https://{REST_HOST}/v2/chainkit/blockhash'
macaroon = codecs.encode(open(MACAROON_PATH, 'rb').read(), 'hex')
headers = {'Grpc-Metadata-macaroon': macaroon}
r = requests.get(url, headers=headers, verify=TLS_PATH)
print(r.json())
# {
#    "block_hash": <bytes>,
# }

Shell

$ lncli chain getblockhash --help

NAME:
   lncli chain getblockhash - Get block hash by block height.

USAGE:
   lncli chain getblockhash [command options] [arguments...]

CATEGORY:
   On-chain

DESCRIPTION:
   Returns the block hash from the best chain at a given height.

OPTIONS:
   --height value  target block height (default: 0)
   

Messages

chainrpc.GetBlockHashRequest

Source: chainrpc/chainkit.proto

Field	gRPC Type	REST Type	REST Placement
block_height Block height of the target best chain block.	int64	string	query

chainrpc.GetBlockHashResponse

Source: chainrpc/chainkit.proto

Field	gRPC Type	REST Type
block_hash The hash of the best block at the specified height.	bytes	string