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 1.7.

    On Linux:

    sudo apt-get install golang-1.8-go
    

    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 wll 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.

  • Glide: This project uses Glide to manage dependencies as well as to provide reproducible builds. To install Glide, execute the following command (assumes you already have Go properly installed):

    go get -u github.com/Masterminds/glide
    

Installing lnd

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

git clone https://github.com/lightningnetwork/lnd $GOPATH/src/github.com/lightningnetwork/lnd
cd $GOPATH/src/github.com/lightningnetwork/lnd
glide install
go install . ./cmd/...

Updating

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

cd $GOPATH/src/github.com/lightningnetwork/lnd
git pull && glide install
go install . ./cmd/...

Tests

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

go install; go test -v -p 1 $(go list ./... | grep -v  '/vendor/')

Installing btcd

lnd currently requires btcd with segwit support, which is not yet merged into the master branch. Instead, roasbeef maintains a fork with his segwit implementation applied. To install, run the following commands:

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

git clone https://github.com/roasbeef/btcd $GOPATH/src/github.com/roasbeef/btcd
cd $GOPATH/src/github.com/roasbeef/btcd
glide install
go install . ./cmd/...

Starting btcd

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

btcd --testnet --txindex --rpcuser=kek --rpcpass=kek

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=kek --rpcpass=kek 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=kek --rpcpass=kek 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 integrate 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 for simnet mode if needed), and also your own btcd node if available:

lnd --bitcoin.active --bitcoin.testnet --debuglevel=debug --neutrino.active --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 installing lnd in preparation for the tutorial, you may skip this step.

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

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 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.

Accurate as of:

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

Next Steps