Agent Skills: LND Lightning Network Skill

LND Lightning Network Skill

LND (Lightning Network Daemon) is a complete implementation of a Lightning Network node. This skill helps you run lnd in Docker for development and testing, with support for multiple backends.

Prerequisites

• Docker and Docker Compose installed
• (Optional) gh CLI for building from GitHub PRs

Quick Start

Start the full regtest stack (Bitcoin Core + LND):

cd ~/.claude/skills/lnd/templates
docker-compose up -d --build   # First time: builds lnd from source (~3-5 min)
docker-compose up -d           # Subsequent runs: uses cached image

This starts:

• lnd-bitcoind: Bitcoin Core 30 in regtest mode with ZMQ
• lnd: LND built from local source

Notes:

• LND is built from source at /users/roasbeef/gocode/src/github.com/lightningnetwork/lnd
• First build takes ~3-5 minutes to compile Go code
• Uses --noseedbackup for testing (no wallet seed required)

Check status:

~/.claude/skills/lnd/scripts/lncli.sh getinfo

Backend Options

LND supports three backend options:

| Backend | Description | Best For | |---------|-------------|----------| | bitcoind | Bitcoin Core | Production, regtest development, interop testing | | btcd | btcd (Go implementation) | Simnet testing, fast iteration | | neutrino | Light client (BIP 157/158) | Testnet, mobile simulation |

Standalone Mode (bitcoind backend - default)

cd ~/.claude/skills/lnd/templates
docker-compose up -d

Shared Mode (interop with eclair)

# First start eclair's stack
cd ~/.claude/skills/eclair/templates
docker-compose up -d

# Then start lnd using eclair's bitcoind
cd ~/.claude/skills/lnd/templates
docker-compose -f docker-compose-shared.yml up -d

btcd Mode (simnet)

cd ~/.claude/skills/lnd/templates
docker-compose -f docker-compose-btcd.yml up -d

Neutrino Mode (light client)

cd ~/.claude/skills/lnd/templates
docker-compose -f docker-compose-neutrino.yml up -d

# Or with signet
NETWORK=signet docker-compose -f docker-compose-neutrino.yml up -d

Docker Management

Build Image (from lnd source)

# Build from current source
~/.claude/skills/lnd/scripts/docker-build.sh

# Build from a specific branch
~/.claude/skills/lnd/scripts/docker-build.sh --branch simple-taproot-chans

# Build from a GitHub PR
~/.claude/skills/lnd/scripts/docker-build.sh --pr 1234

# Build from a specific commit
~/.claude/skills/lnd/scripts/docker-build.sh --commit abc123

# Quick PR build (convenience wrapper)
~/.claude/skills/lnd/scripts/build-pr.sh 1234

Start Containers

# Start standalone stack (bitcoind + lnd)
~/.claude/skills/lnd/scripts/docker-start.sh

# Start in shared mode (uses external bitcoind)
~/.claude/skills/lnd/scripts/docker-start.sh --shared

# Start with btcd backend
~/.claude/skills/lnd/scripts/docker-start.sh --btcd

# Start in neutrino mode
~/.claude/skills/lnd/scripts/docker-start.sh --neutrino

# Rebuild before starting
~/.claude/skills/lnd/scripts/docker-start.sh --build

Stop Containers

# Stop containers (preserve data)
~/.claude/skills/lnd/scripts/docker-stop.sh

# Stop and remove volumes (clean state)
~/.claude/skills/lnd/scripts/docker-stop.sh --clean

View Logs

docker logs -f lnd
docker logs -f lnd-bitcoind

Essential lncli Operations

All commands use lncli.sh wrapper which auto-detects the lnd container.

Node Information

# Get node info
~/.claude/skills/lnd/scripts/lncli.sh getinfo

# Get wallet balance (on-chain)
~/.claude/skills/lnd/scripts/lncli.sh walletbalance

# Get channel balance (Lightning)
~/.claude/skills/lnd/scripts/lncli.sh channelbalance

Wallet & Addresses

# Get new address (native SegWit)
~/.claude/skills/lnd/scripts/lncli.sh newaddress p2wkh

# Get new address (nested SegWit)
~/.claude/skills/lnd/scripts/lncli.sh newaddress np2wkh

# Get new Taproot address
~/.claude/skills/lnd/scripts/lncli.sh newaddress p2tr

# Send on-chain
~/.claude/skills/lnd/scripts/lncli.sh sendcoins --addr=<address> --amt=<satoshis>

Connect to Peers

# Connect by URI
~/.claude/skills/lnd/scripts/lncli.sh connect <pubkey>@<host>:9735

# List connected peers
~/.claude/skills/lnd/scripts/lncli.sh listpeers

# Disconnect
~/.claude/skills/lnd/scripts/lncli.sh disconnect <pubkey>

Channel Management

# Open channel
~/.claude/skills/lnd/scripts/lncli.sh openchannel --node_key=<pubkey> --local_amt=1000000

# List channels
~/.claude/skills/lnd/scripts/lncli.sh listchannels

# Get channel balance
~/.claude/skills/lnd/scripts/lncli.sh channelbalance

# Close channel cooperatively
~/.claude/skills/lnd/scripts/lncli.sh closechannel --funding_txid=<txid> --output_index=<n>

# Force close channel
~/.claude/skills/lnd/scripts/lncli.sh closechannel --funding_txid=<txid> --output_index=<n> --force

Payments

# Create invoice
~/.claude/skills/lnd/scripts/lncli.sh addinvoice --amt=<satoshis> --memo="test payment"

# Decode invoice
~/.claude/skills/lnd/scripts/lncli.sh decodepayreq <bolt11_invoice>

# Pay invoice
~/.claude/skills/lnd/scripts/lncli.sh sendpayment --pay_req=<bolt11_invoice>

# List payments
~/.claude/skills/lnd/scripts/lncli.sh listpayments

# List invoices
~/.claude/skills/lnd/scripts/lncli.sh listinvoices

Regtest Development Workflow

1. Start the Stack

cd ~/.claude/skills/lnd/templates
docker-compose up -d

2. Initialize Regtest Environment

# Automated setup: mines blocks, funds lnd wallet
~/.claude/skills/lnd/scripts/regtest-setup.sh

Or manually:

# Mine blocks for coinbase maturity
~/.claude/skills/lnd/scripts/mine.sh 101

# Get lnd address
LND_ADDR=$(~/.claude/skills/lnd/scripts/lncli.sh newaddress p2wkh | jq -r '.address')

# Send funds to lnd
~/.claude/skills/lnd/scripts/bitcoin-cli.sh sendtoaddress $LND_ADDR 10

# Confirm transaction
~/.claude/skills/lnd/scripts/mine.sh 1

# Check balance
~/.claude/skills/lnd/scripts/lncli.sh walletbalance

3. Open a Channel (with second node)

# Connect to peer
~/.claude/skills/lnd/scripts/lncli.sh connect <nodeId>@<host>:9735

# Open 1M sat channel
~/.claude/skills/lnd/scripts/lncli.sh openchannel --node_key=<nodeId> --local_amt=1000000

# Mine blocks to confirm channel
~/.claude/skills/lnd/scripts/mine.sh 6

# Check channel status
~/.claude/skills/lnd/scripts/lncli.sh listchannels

4. Send a Payment

# On receiving node: create invoice
INVOICE=$( lncli addinvoice --amt=50000 --memo="test" | jq -r '.payment_request')

# On sending node: pay invoice
~/.claude/skills/lnd/scripts/lncli.sh sendpayment --pay_req=$INVOICE

Multi-Node Testing

Run multiple lnd nodes for peer-to-peer testing:

Start Multi-Node Stack

# Start alice and bob nodes
~/.claude/skills/lnd/scripts/docker-start.sh --multi --build

# Or with docker-compose directly
cd ~/.claude/skills/lnd/templates
docker-compose -f docker-compose-multi.yml up -d --build

Initialize Multi-Node Environment

# Full setup: fund wallets and open channel between alice and bob
~/.claude/skills/lnd/scripts/multi-node-setup.sh

# Or without channel
~/.claude/skills/lnd/scripts/multi-node-setup.sh --no-channel

Multi-Node Commands

# Use --node flag to specify which node
~/.claude/skills/lnd/scripts/lncli.sh --node alice getinfo
~/.claude/skills/lnd/scripts/lncli.sh --node bob getinfo

# Get pubkeys
ALICE_PUBKEY=$(~/.claude/skills/lnd/scripts/lncli.sh --node alice getinfo | jq -r '.identity_pubkey')
BOB_PUBKEY=$(~/.claude/skills/lnd/scripts/lncli.sh --node bob getinfo | jq -r '.identity_pubkey')

# Connect nodes
~/.claude/skills/lnd/scripts/lncli.sh --node alice connect ${BOB_PUBKEY}@lnd-bob:9735

# Open channel
~/.claude/skills/lnd/scripts/lncli.sh --node alice openchannel --node_key=$BOB_PUBKEY --local_amt=1000000

# Send payment from alice to bob
INVOICE=$(~/.claude/skills/lnd/scripts/lncli.sh --node bob addinvoice --amt=10000 | jq -r '.payment_request')
~/.claude/skills/lnd/scripts/lncli.sh --node alice sendpayment --pay_req=$INVOICE

Multi-Node Ports

| Node | P2P Port | gRPC Port | REST Port | |------|----------|-----------|-----------| | alice | 9735 | 10009 | 8080 | | bob | 9736 | 10010 | 8081 | | charlie | 9737 | 10011 | 8082 |

Interop Testing with Eclair

Test channel operations between lnd and eclair:

# Terminal 1: Start eclair stack
cd ~/.claude/skills/eclair/templates
docker-compose up -d
~/.claude/skills/eclair/scripts/regtest-setup.sh

# Terminal 2: Start lnd with shared bitcoind
cd ~/.claude/skills/lnd/templates
docker-compose -f docker-compose-shared.yml up -d --build

# Wait for lnd to sync, then run setup
sleep 10
~/.claude/skills/lnd/scripts/regtest-setup.sh --quick

# Get eclair's pubkey
ECLAIR_PUBKEY=$(docker exec eclair eclair-cli -p devpassword getinfo | jq -r '.nodeId')
echo "Eclair pubkey: $ECLAIR_PUBKEY"

# Connect lnd to eclair
~/.claude/skills/lnd/scripts/lncli.sh connect ${ECLAIR_PUBKEY}@eclair:9735

# Open channel from lnd to eclair
~/.claude/skills/lnd/scripts/lncli.sh openchannel --node_key=$ECLAIR_PUBKEY --local_amt=1000000

# Mine to confirm
~/.claude/skills/eclair/scripts/mine.sh 6

# Check channels on both sides
~/.claude/skills/lnd/scripts/lncli.sh listchannels
docker exec eclair eclair-cli -p devpassword channels

Custom Arguments and Profiles

Pass extra arguments to lnd via LND_EXTRA_ARGS:

# Enable REST API on different port
LND_EXTRA_ARGS="--restlisten=0.0.0.0:8081" docker-compose up -d

# Enable debug logging for specific subsystems
LND_EXTRA_ARGS="--debuglevel=HSWC=trace,PEER=debug" docker-compose up -d

# Multiple extra args
LND_EXTRA_ARGS="--protocol.wumbo-channels --maxchansize=500000000" docker-compose up -d

Build Tags

LND supports various build tags for optional features:

| Tag | Description | |-----|-------------| | signrpc | Signing RPC service | | walletrpc | Wallet RPC service | | chainrpc | Chain RPC service | | invoicesrpc | Invoices RPC service | | routerrpc | Router RPC service | | peersrpc | Peers RPC service | | neutrinorpc | Neutrino RPC service | | watchtowerrpc | Watchtower RPC service | | kvdb_sqlite | SQLite database backend | | kvdb_postgres | PostgreSQL database backend | | dev | Development features |

Build with custom tags:

~/.claude/skills/lnd/scripts/docker-build.sh --tags "signrpc walletrpc routerrpc dev"

Helper Scripts

| Script | Description | |--------|-------------| | docker-build.sh | Build lnd image with branch/PR/commit support | | docker-start.sh | Start containers with mode selection | | docker-stop.sh | Stop containers, optionally clean volumes | | lncli.sh | Wrapper for lncli with container and node auto-detection | | bitcoin-cli.sh | Wrapper for bitcoin-cli | | mine.sh | Mine regtest blocks | | regtest-setup.sh | Initialize regtest with funded wallet | | multi-node-setup.sh | Initialize multi-node with funded wallets and channels | | build-pr.sh | Quick PR build convenience wrapper |

Environment Variables

| Variable | Description | Default | |----------|-------------|---------| | LND_SOURCE | Path to lnd source directory | /users/roasbeef/gocode/src/github.com/lightningnetwork/lnd | | LND_IMAGE | Docker image tag | lnd:local | | LND_DEBUG | Log level | debug | | LND_EXTRA_ARGS | Additional lnd arguments | (empty) | | NETWORK | Bitcoin network | regtest | | BACKEND | Backend: bitcoind, btcd, neutrino | bitcoind |

Ports

| Port | Service | Description | |------|---------|-------------| | 9735 | Lightning | Peer-to-peer Lightning protocol | | 10009 | gRPC | LND RPC (for lncli) | | 8080 | REST | REST API | | 18443 | Bitcoin RPC | Bitcoin Core RPC (regtest) | | 28332 | ZMQ | Block notifications | | 28333 | ZMQ | Transaction notifications |

Troubleshooting

"transport: Error while dialing dial tcp: connection refused"

• LND is still starting up. Wait a few seconds and retry.
• Check logs: docker logs lnd

"unable to find a path to destination"

• No route to the destination. Check channel balances.
• Run: lncli.sh listchannels to see local/remote balances

Channel stuck in "pending open"

• Mine blocks to confirm: ~/.claude/skills/lnd/scripts/mine.sh 6

"insufficient funds available"

• Check wallet balance: lncli.sh walletbalance
• Fund wallet using regtest-setup.sh

"rpc error: code = Unknown desc = chain backend is still syncing"

• LND is syncing with the blockchain. Wait for sync to complete.
• Check: lncli.sh getinfo and look at synced_to_chain

Build fails with "go: module requires Go X.Y"

• Update Go version or use --prod flag for production Dockerfile

Further Reading

• API Reference - gRPC and REST API documentation
• LND GitHub - Official repository
• LND Documentation - Official docs
• BOLT Specifications - Lightning Network protocol specs