Preliminaries

In order to work with lnd, the following build dependencies are required:

  • Go: lnd is written in Go. To install, run one of the following commands:

    Note: The minimum version of Go supported is Go 1.9. We recommend that users use the latest version of Go, which at the time of writing is 1.10.

    On Linux:

    sudo apt-get install golang-1.10-go
    

    Note that golang-1.10-go puts binaries in /usr/lib/go-1.10/bin. If you want them on your PATH, you need to make that change yourself.

    On Mac OS X

    brew install go
    

    Alternatively, one can download the pre-compiled binaries hosted on the golang download page. If one seeks to install from source, then more detailed installation instructions can be found here.

    At this point, you should set your $GOPATH environment variable, which represents the path to your workspace. By default, $GOPATH is set to ~/go. You will also need to add $GOPATH/bin to your PATH. This ensures that your shell will be able to detect the binaries you install.

    export GOPATH=~/gocode
    export PATH=$PATH:$GOPATH/bin
    

    We recommend placing the above in your .bashrc or in a setup script so that you can avoid typing this every time you open a new terminal window.

  • dep: This project uses dep to manage dependencies as well as to provide reproducible builds.

    Note: dep is automatically installed via the make. To fetch dep manually, use the following command (assumes you already have Go properly installed):

    go get -u github.com/golang/dep/cmd/dep
    

Installing lnd

With the preliminary steps completed, to install lnd, lncli, and all related dependencies run the following commands:

go get -d github.com/lightningnetwork/lnd
cd $GOPATH/src/github.com/lightningnetwork/lnd
make && make install

Updating

To update your version of lnd to the latest version run the following commands:

git pull
make && make install

Tests

To check that lnd was installed properly run the following command:

make check

Installing btcd

When using the btcd backend, lnd currently requires the roasbeef fork of btcd due to neutrino additions that are not yet available in the master branch. To install, run the following commands:

Install btcd: (must be from roasbeef fork, not from btcsuite)

make btcd 

Starting btcd

Running the following command will create rpc.cert and default btcd.conf.

btcd --testnet --txindex --rpcuser=REPLACEME --rpcpass=REPLACEME

If you want to use lnd on testnet, btcd needs to first fully sync the testnet blockchain. Depending on your hardware, this may take up to a few hours.

(NOTE: It may take several minutes to find segwit-enabled peers.)

While btcd is syncing you can check on its progress using btcd’s getinfo RPC command:

btcctl --testnet --rpcuser=REPLACEME --rpcpass=REPLACEME getinfo
{
  "version": 120000,
  "protocolversion": 70002,
  "blocks": 1114996, 
  "timeoffset": 0,
  "connections": 7,
  "proxy": "",
  "difficulty": 422570.58270815,
  "testnet": true,
  "relayfee": 0.00001,
  "errors": ""
}

Additionally, you can monitor btcd’s logs to track its syncing progress in real time.

You can test your btcd node’s connectivity using the getpeerinfo command:

btcctl --testnet --rpcuser=REPLACEME --rpcpass=REPLACEME getpeerinfo | more

lnd

Simnet vs. Testnet Development

If you are doing local development, such as for the tutorial, you’ll want to start both btcd and lnd in the simnet mode. Simnet is similar to regtest in that you’ll be able to instantly mine blocks as needed to test lnd locally. In order to start either daemon in the simnet mode use simnet instead of testnet, adding the --bitcoin.simnet flag instead of the --bitcoin.testnet flag.

Another relevant command line flag for local testing of new lnd developments is the --debughtlc flag. When starting lnd with this flag, it’ll be able to automatically settle a special type of HTLC sent to it. This means that you won’t need to manually insert invoices in order to test payment connectivity. To send this “special” HTLC type, include the --debugsend command at the end of your sendpayment commands.

There are currently two primary ways to run lnd: one requires a local btcd instance with the RPC service exposed, and the other uses a fully integrated light client powered by neutrino.

Running lnd in Light Client Mode

In order to run lnd in its light client mode, you’ll need to locate a full-node which is capable of serving this new light client mode. A BIP draft exists, and will be finalized in the near future, but for now you’ll need to be running roasbeef’s fork of btcd. A public instance of such a node can be found at faucet.lightning.community.

To run lnd in neutrino mode, run lnd with the following arguments, (swapping in --bitcoin.simnet if needed), and also your own btcd node if available:

lnd --bitcoin.active --bitcoin.testnet --debuglevel=debug --bitcoin.node=neutrino --neutrino.connect=faucet.lightning.community

Running lnd using the btcd backend

If you are on testnet, run this command after btcd has finished syncing. Otherwise, replace --bitcoin.testnet with --bitcoin.simnet. If you are installing lnd in preparation for the tutorial, you may skip this step.

lnd --bitcoin.active --bitcoin.testnet --debuglevel=debug --btcd.rpcuser=kek --btcd.rpcpass=kek --externalip=X.X.X.X

Running lnd using the bitcoind or litecoind backend

The configuration for bitcoind and litecoind are nearly identical, the following steps can be mirrored with loss of generality to enable a litecoind backend. Setup will be described in regards to bitcoind, but note that lnd uses a distinct litecoin.node=litecoind argument and analogous subconfigurations prefixed by litecoind.

To configure your bitcoind backend for use with lnd, first complete and verify the following:

  • The bitcoind instance must be configured with --txindex just like btcd above
  • Additionally, since lnd uses ZeroMQ to interface with bitcoind, your bitcoind installation must be compiled with ZMQ. If you installed it from source, this is likely the case, but if you installed it via Homebrew in the past it may not be included (this has now been fixed in the latest Homebrew recipe for bitcoin)
  • Configure the bitcoind instance for ZMQ with --zmqpubrawblock and --zmqpubrawtx (the latter is optional but allows you to see unconfirmed transactions in your wallet). They must be combined in the same ZMQ socket address (e.g. --zmqpubrawblock=tcp://127.0.0.1:28332 and --zmqpubrawtx=tcp://127.0.0.1:28332).
  • Start bitcoind running against testnet, and let it complete a full sync with the testnet chain (alternatively, use --bitcoind.regtest instead).

Here’s a sample bitcoin.conf for use with lnd:

testnet=1
txindex=1
server=1
daemon=1
zmqpubrawblock=tcp://127.0.0.1:28332
zmqpubrawtx=tcp://127.0.0.1:28332

Once all of the above is complete, and you’ve confirmed bitcoind is fully updated with the latest blocks on testnet, run the command below to launch lnd with bitcoind as your backend (as with bitcoind, you can create an lnd.conf to save these options, more info on that is described further below):

lnd --bitcoin.active --bitcoin.testnet --debuglevel=debug --bitcoin.node=bitcoind --bitcoind.rpcuser=REPLACEME --bitcoind.rpcpass=REPLACEME --bitcoind.zmqpath=tcp://127.0.0.1:28332 --externalip=X.X.X.X

NOTE:

  • The auth parameters rpcuser and rpcpass parameters can typically be determined by lnd for a bitcoind instance running under the same user, including when using cookie auth. In this case, you can exclude them from the lnd options entirely.
  • If you DO choose to explicitly pass the auth parameters in your lnd.conf or command line options for lnd (bitcoind.rpcuser and bitcoind.rpcpass as shown in example command above), you must also specify the bitcoind.zmqpath option. Otherwise, lnd will attempt to get the configuration from your bitcoin.conf.
  • You must ensure the same address (including port) is used for the bitcoind.zmqpath option passed to lnd as for the zmqpubrawblock and zmqpubrawtx passed in the bitcoind options.

Disabling Wallet Encryption

To disable encryption of the wallet files, pass the --noencryptwallet argument to lnd. Obviously beware the security implications of running an unencrypted wallet - this argument must only be used for testing purposes.

Macaroons

lnd’s authentication system is called macaroons, which are decentralized bearer credentials allowing for delegation, attenuation, and other cool features. You can learn more about them in Alex Akselrod’s writeup on Github.

Running lnd for the first time will by default generate the admin.macaroon, read_only.macaroon, and macaroons.db files that are used to authenticate into lnd. They will be stored in the default lnd data directory. Note that if you specified an alternative data directory (via the --datadir argument), you will have to additionally pass the updated location of the admin.macaroon file into lncli using the --macaroonpath argument.

To disable macaroons for testing, pass the --no-macaroons flag into both lnd and lncli.

Network Reachability

If you’d like to signal to other nodes on the network that you’ll accept incoming channels (as peers need to connect inbound to initiate a channel funding workflow), then the --externalip flag should be set to your publicly reachable IP address.

Creating an lnd.conf (Optional)

Optionally, if you’d like to have a persistent configuration between lnd launches, allowing you to simply type lnd --bitcoin.testnet --bitcoin.active at the command line, you can create an lnd.conf.

On MacOS, located at: /Users/[username]/Library/Application Support/Lnd/lnd.conf

On Linux, located at: ~/.lnd/lnd.conf

Here’s a sample lnd.conf for btcd to get you started:

[Application Options]
debuglevel=trace
debughtlc=true
maxpendingchannels=10

[Bitcoin]
bitcoin.active=1

Notice the [Bitcoin] section. This section houses the parameters for the Bitcoin chain. lnd also supports Litecoin testnet4 (but not both BTC and LTC at the same time), so when working with Litecoin be sure to set to parameters for Litecoin accordingly. For node configuration, the sections are called [Btcd], [Bitcoind], [Neutrino], [Ltcd], and [Litecoind] depending on which chain and node type you’re using.

Accurate as of:

  • roasbeef/btcd commit: f8c02aff4e7a807ba0c1349e2db03695d8e790e8
  • roasbeef/btcutil commit: a259eaf2ec1b54653cdd67848a41867f280797ee
  • lightningnetwork/lnd commit: 08de2becf8d77fae192205172c4fb17bb09bd0dbf49e64aa323b2fcbf9fe2a35

Next Steps