FundChannel

FundChannel initiates the channel funding negotiation with a peer for the creation of a channel that contains a specified amount of a given asset.

Source: tapchannelrpc/tapchannel.proto

gRPC

rpc FundChannel (FundChannelRequest) returns (FundChannelResponse);

REST

HTTP Method	Path
GET	/v1/taproot-assets/channels/fund

Code Samples

gRPC

Javascript

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

const GRPC_HOST = 'localhost:10029'
const MACAROON_PATH = 'TAPROOT-ASSETS_DIR/regtest/taproot-assets.macaroon'
const TLS_PATH = 'TAPROOT-ASSETS_DIR/tls.cert'

const loaderOptions = {
  keepCase: true,
  longs: String,
  enums: String,
  defaults: true,
  oneofs: true,
};
const packageDefinition = protoLoader.loadSync('tapchannelrpc/tapchannel.proto', loaderOptions);
const tapchannelrpc = grpc.loadPackageDefinition(packageDefinition).tapchannelrpc;
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 tapchannelrpc.TaprootAssetChannels(GRPC_HOST, creds);
let request = {
  asset_amount: <uint64>,
  asset_id: <bytes>,
  peer_pubkey: <bytes>,
  fee_rate_sat_per_vbyte: <uint32>,
  push_sat: <int64>,
};
client.fundChannel(request, function(err, response) {
  console.log(response);
});
// Console output:
//  {
//    "txid": <string>,
//    "output_index": <int32>,
//  }

Python

import codecs, grpc, os
# Generate the following 2 modules by compiling the tapchannelrpc/tapchannel.proto with the grpcio-tools.
# See https://github.com/lightningnetwork/lnd/blob/master/docs/grpc/python.md for instructions.
import tapchannel_pb2 as tapchannelrpc, tapchannel_pb2_grpc as tapchannelstub

GRPC_HOST = 'localhost:10029'
MACAROON_PATH = 'TAPROOT-ASSETS_DIR/regtest/taproot-assets.macaroon'
TLS_PATH = 'TAPROOT-ASSETS_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 = tapchannelstub.TaprootAssetChannelsStub(channel)
request = tapchannelrpc.FundChannelRequest(
  asset_amount=<uint64>,
  asset_id=<bytes>,
  peer_pubkey=<bytes>,
  fee_rate_sat_per_vbyte=<uint32>,
  push_sat=<int64>,
)
response = stub.FundChannel(request)
print(response)
# {
#    "txid": <string>,
#    "output_index": <int32>,
# }

REST

Javascript

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

const REST_HOST = 'localhost:8089'
const MACAROON_PATH = 'TAPROOT-ASSETS_DIR/regtest/taproot-assets.macaroon'

let options = {
  url: `https://${REST_HOST}/v1/taproot-assets/channels/fund`,
  // 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:
//  {
//    "txid": <string>, // <string> 
//    "output_index": <integer>, // <int32> 
//  }

Python

import base64, codecs, json, requests

REST_HOST = 'localhost:8089'
MACAROON_PATH = 'TAPROOT-ASSETS_DIR/regtest/taproot-assets.macaroon'
TLS_PATH = 'TAPROOT-ASSETS_DIR/tls.cert'

url = f'https://{REST_HOST}/v1/taproot-assets/channels/fund'
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())
# {
#    "txid": <string>,
#    "output_index": <int32>,
# }

Shell

# There is no CLI command for this RPC

Messages

tapchannelrpc.FundChannelRequest

Source: tapchannelrpc/tapchannel.proto

Field	gRPC Type	REST Type	REST Placement
asset_amount The asset amount to fund the channel with. The BTC amount is fixed and cannot be customized (for now).	uint64	string	query
asset_id The asset ID to use for the channel funding.	bytes	string	query
peer_pubkey The public key of the peer to open the channel with. Must already be connected to this peer.	bytes	string	query
fee_rate_sat_per_vbyte The channel funding fee rate in sat/vByte.	uint32	integer	query
push_sat The number of satoshis to give the remote side as part of the initial commitment state. This is equivalent to first opening a channel and then sending the remote party funds, but all done in one step. Therefore, this is equivalent to a donation to the remote party, unless they reimburse the funds in another way (outside the protocol).	int64	string	query

tapchannelrpc.FundChannelResponse

Source: tapchannelrpc/tapchannel.proto

Field	gRPC Type	REST Type
txid The channel funding transaction ID.	string	string
output_index The index of the channel funding output in the funding transaction.	int32	integer