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bitcoind/Bitcoin Core

Downloading bitcoind

The Bitcoin Core RPC client in Bitcoin-S currently supports the Bitcoin Core

• 0.16
• 0.17
• 0.18
• 0.19
• 0.20
• 0.21

version lines. It can be set up to work with both local and remote Bitcoin Core servers.

You can fetch them using bitcoin-s by running the following sbt command. If you already have bitcoind installed on your machine, you can skip this step.

sbt downloadBitcoind

The binaries will be stored in ~/.bitcoin-s/binaries/bitcoind/

Connecting to a local bitcoind instance

Getting started quickly, with default options:

implicit val ec: ExecutionContext = ExecutionContext.global

// this reads authentication credentials and
// connection details from the default data
// directory on your platform
val client = BitcoindRpcClient.fromDatadir(binary=new File("/path/to/bitcoind"), datadir=new File("/path/to/bitcoind-datadir"))

val balance: Future[Bitcoins] = for {
  _ <- client.start()
  balance <- client.getBalance
} yield balance

Multi-wallet bitcoind instances

When using the bitcoind with multiple wallets you will need to specify the wallet's name. To do so the wallet rpc functions have an optional walletName parameter.

implicit val ec: ExecutionContext = ExecutionContext.global

val client = BitcoindRpcClient.fromDatadir(binary=new File("/path/to/bitcoind"), datadir=new File("/path/to/bitcoind-datadir"))

for {
  _ <- client.start()
  _ <- client.walletPassphrase("mypassword", 10000, Some("walletName"))
  balance <- client.getBalance("walletName")
} yield ()

Connecting to a remote bitcoind

First, we create a secure connection to our bitcoind instance by setting up a SSH tunnel:

ssh -L 8332:localhost:8332 [email protected]

Note: the port number '8332' is the default for mainnet. If you want to connect to a testnet bitcoind, the default port is '18332'

Now that we have a secure connection between our remote bitcoind, we're ready to create the connection with our RPC client

implicit val ec: ExecutionContext = ExecutionContext.global

val username = "FILL_ME_IN" //this username comes from 'rpcuser' in your bitcoin.conf file //this username comes from 'rpcuser' in your bitcoin.conf file
val password = "FILL_ME_IN" //this password comes from your 'rpcpassword' in your bitcoin.conf file //this password comes from your 'rpcpassword' in your bitcoin.conf file

val authCredentials = BitcoindAuthCredentials.PasswordBased(
  username = username,
  password = password
)

val bitcoindInstance = {
  BitcoindInstance (
    network = MainNet,
    uri = new URI(s"http://localhost:${MainNet.port}"),
    rpcUri = new URI(s"http://localhost:${MainNet.rpcPort}"),
    authCredentials = authCredentials
  )
}

val rpcCli = BitcoindRpcClient(bitcoindInstance)

rpcCli.getBalance.onComplete { case balance =>
  println(s"Wallet balance=${balance}")
}

Error handling

All errors returned by Bitcoin Core are mapped to a corresponding BitcoindException. These exceptions contain an error code and a message. BitcoindException is a sealed trait, which means you can easily pattern match exhaustively. Of course, other errors could also happen: network errors, stack overflows or out-of-memory errors. The provided class is only intended to cover errors returned by Bitcoin Core. An example of how error handling could look:

implicit val ec = ExecutionContext.global

// let's assume you have an already running client,
// so there's no need to start this one
val cli = BitcoindRpcClient.fromDatadir(binary=new File("/path/to/bitcoind"), datadir=new File("/path/to/bitcoind-datadir"))

// let's also assume you have a bitcoin address
val address: BitcoinAddress = ???

val txid: Future[DoubleSha256DigestBE] =
  cli.sendToAddress(address, 3.bitcoins).recoverWith {
    case BitcoindWalletException.UnlockNeeded(_) =>
      cli.walletPassphrase("my_passphrase", 60).flatMap { _ =>
        cli.sendToAddress(address, 3.bitcoins)
      }
  }