Setting up Boltz-client on your LND Lightning Node

Automagically receive Lightning transactions on your node from a Bitcoin On-chain payment

We want to run boltz-client using a LND Lightning node running on Voltage. Of course you can use a different installation. What you need is the macaroon and the tls.cert . You can get them from Voltage if you are using such a facility. In this example LND is running on Voltage and we are working on a Debian VPS where we are going to install the Boltz client.

Install the client

Create a directory let’s say boltz-client and put the following docker-compose.yml file

version: "3"
  
services:
    boltzd:
        container_name: boltz-client
        hostname: boltzd-client
        image: boltz/boltz-client:latest
        restart: on-failure
        volumes:
          - ${PWD}/.boltz:/root/.boltz
          - ${PWD}/.lnd:/root/.lnd

get the prebuilt image

docker pull boltz/boltz-client:latest

now create the dirs

mkdir .boltz
mkdir .lnd

Create the file .boltz/boltz.toml with the following content:

# Path to the log file
logfile = ""

# possible values: fatal, error, warn, info, debug, silly
loglevel = "info"

# possible values: "mainnet", "testnet" or "regtest"
network = "mainnet"

# you will have to set this to "cln" or "lnd" if you have configuration values for both
node = "lnd"

[BOLTZ]
# By default the daemon automatically connects to the official Boltz Backend for the network your node is on
# This value is used to overwrite that
 url = "https://api.boltz.exchange"

[DATABASE]
# Path to the SQLite database file
# path = "~/test.db"

[LND]
# Host of the gRPC interface of LND
# host = "127.0.0.1"
host = "yournode.m.voltageapp.io"


# Port of the gRPC interface of LND
 port = 10009

# Path to the data directory of LND
 datadir = "~/.lnd"

# Path to a macaroon file of LND.
# The daemon needs to have permission to read various endpoints, generate addresses and pay invoices
# Not required if datadir is specified
 macaroon = "~/.lnd/data/chain/bitcoin/mainnet/admin.macaroon"

# Path to the TLS certificate of LND
# Not required if datadir is specified
 certificate = "~/.lnd/tls.cert"

[CLN]
# Host of the gRPC interface of CLN
# host = "127.0.0.1"

# Port of the gRPC interface of CLN
# port = 9736

# Path to the data directory of CLN
# datadir = "~/.lightning"

# Paths to TLS certificates and keys of CLN. Not required if datadir is specified
# rootcert = "~/.lightning/bitcoin/ca.pem"
# privatekey = "~/.lightning/bitcoin/client-key.pem"
# certchain =  "~/.lightning/bitcoin/client.pem"

[RPC]
# Host of the gRPC interface
host = "127.0.0.1"

# Port of the gRPC interface
port = 9002

# Whether the REST proxy for the gRPC interface should be disabled
restDisabled = false

# Host of the REST proxy
restHost = "127.0.0.1"

# Port of the REST proxy
restPort = 9003

# Path to the TLS cert for the gRPC and REST interface
tlsCert = ""

# Path to the TLS private key for the gRPC and REST interface
tlsKey = ""

# Whether the macaroon authentication for the gRPC and REST interface should be disabled
noMacaroons = false

# Path to the admin macaroon for the gRPC and REST interface
adminMacaroonPath = ""

# Path to the read-only macaroon for the gRPC and REST interface
readOnlyMacaroonPath = ""

The .lnd/ must contain macaroon and tls.cert coming from your node.

Now you can start your container by running:

docker-compose up -d

Create a Onchain to Lightning Swap

Now you can create a new swap from Onchain to Lightning. In this case the swap will receive an onchain transaction and simultaneously issue a corresponding Lightning invoice of the same amount less fees.

dev@lnbits00:~/boltz-client$ docker exec -ti boltz-client boltzcli createswap --any-amount btc
The fees for this service are:
  - Boltz fee: 0.1%
  - Network fee: 453 satoshis

? Do you want to continue? Yes
Please deposit between 25000 and 25000000 satoshis into bc1pwk4w6xxx in the next ~24.0 hours (block height 879106)

Swap ID: zoZXkKI2b2cy
Status: swap.created

Now you should send the amount you want to swap to the above displayed address from Boltz. When you do that you will get

Status: transaction.mempool
Transaction ID: 34b9fa3adb36d391d987c1e29655aa3e32f7617883d225adxxxx
Amount: 350778sat

Status: invoice.set
Invoice: lnbc3499750n1pncgzz3pp5y2gt9jgjul5463cku7trmrf6tcurw6y7asj8ugmhmchufdjxnshqdp92d6kymtpwf5kuefq2dmkzupqveex7mfqgf2yxcqzzsxqyz57csp5hmde9aylmmwknvvafls8rvy9uefejx46kk0nq99pemencjeru3nq9p4gqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqpqysgqremn6xuur8dmq5j2akygxd2v488lv525sjjm0r76f94cyvywjee88sq03l6qputm5apymnad2z6hmxmw64d8s69galsplqqqxxxxxxxxx

Status: transaction.confirmed

Status: invoice.pending

Status: invoice.paid

Status: transaction.claim.pending

Status: transaction.claimed
Paid 453 sat onchain fee and 350 sat boltz fee

Checking the swap will result:

dev@lnbits00:~/boltz-client$ docker exec -ti boltz-client boltzcli listswaps
Type       ID            From  To   State       Status               Send Amount  Boltz Fee  Network Fee  Created At            
SUBMARINE  zoZXkKI2b2cy  BTC   BTC  SUCCESSFUL  transaction.claimed  350778       350        453          2025-01-12T18:21:29Z 

Automagically, when the transaction gets confirmed on the timechain, you will get the incoming payment

💵 Received 0.00349975 for “Submarine Swap from BTC” via WCC-BOUNCER

directly on your node! The magic happened:

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