ln-payments

Full-stack application that enables Lightning Network invoice payments.

1. overall architecture
2. deployment
   1. polar configuration
   2. services connfiguration
   3. launch services
3. development
4. applications documentation

overall architecture

flowchart LR
  subgraph polar
  receiver
  sender
  end

  api <-->|lnd connection| polar
  api <-->|pg pool| postgres
  frontend <-->|http| api
  postgres[(postgres)] --> adminer

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• Polar - One-click Bitcoin Lightning networks for local app development & testing.
• api - RESTful API to connect to Lightning nodes.
• frontend - React + Vite UI to interact with LN payments.
• postgres - Relational database to persist LN transactions.
• adminer - Database management.

deployment

polar configuration

Polar is a one-click Bitcoin Lightning networks for local app development & testing. In order to get up and running, follow the above steps:

1. Download and install Polar in the official site. For Unix-like machines that can execute AppImages, download and execute:

chmod u+x /path/to/polar-linux-x86_64-v4.0.0.AppImag
./path/to/polar-linux-x86_64-v4.0.0.AppImag

2. Create a network with 2 LND and 1 Bitcoin Core.

3. Start the network. Can take several minutes to pull Docker images and run them.

4. Create a channel between node Bob and Alice.

5. Perform a quick mine to verify the network.

6. Edit apps/api/.env.example to fit connection data for each node (HEX encoded).

services configuration

Each service has its own .env.example environment file. This examples will work as provided just renaming to .env in the following paths:

• .env.example - Postgres creation variables.

Name	Description	Default
POSTGRES_USER	Postgres user name	postgres
POSTGRES_PASSWORD	Postgres user password	postgres-password
POSTGRES_DB	Postgres databse name	ln-payments

• apps/api/.env.example - Please refer to api README.

Name	Description	Default
RECEIVER_SOCKET	Receiver URL	polar-n1-bob:10009
RECEIVER_CERT	Receiver HEX encoded TLS cert	Some TLS cert
RECEIVER_MACAROON	Receiver HEX encoded admin macaroon	Some admin macaroon
RECEIVER_PUBLIC_KEY	Receiver public key	Some public key
SENDER_SOCKET	Sender URL	polar-n1-alice:10009
SENDER_CERT	Sender HEX encoded TLS cert	Some TLS cert
SENDER_MACAROON	Sender HEX encoded admin macaroon	Some admin macaroon
SENDER_PUBLIC_KEY	Sender public key	Some public key
POSTGRES_HOST	Postgre host to connect with	postgres
UI_PORT	UI listen port to enable socket.io CORS	4000

Note: above hostnames are resolved internally to the attached Docker network. If yoy have any other Polar network running minor changes will be required to fit RECEIVER_SOCKET, SENDER_SOCKET and network at compose.yaml assigning the correct id to polar-n<id>-bob, polar-n<id>-alice and polar-network-<id>_default respectively. Check can be done executing docker ps and looking for polar sevices.

• apps/frontend/.env.example - Please refer to frontend README.

Name	Description	Default
VITE_API_URL	api service URL	http://api:3000
VITE_EMITTER_SOCKET	invoice emitter URL	polar-n1-bob:10009
VITE_EMITTER_CERT	invoice emitter HEX TLS cert	some hex string
VITE_EMITTER_MACAROON	invoice emitter HEX admin macaroon	some hex string
VITE_PAYER_SOCKET	invoice payer URL	polar-n1-alice:10009
VITE_PAYER_CERT	invoice payer HEX TLS cert	some hex string
VITE_PAYER_MACAROON	invoice payer HEX admin macaroon	some hex string

Please, modify to fit your needs.

launch services

To launch services launch compose file:

cp .env.example .env
cp apps/api/.env.example apps/api/.env
cp apps/frontend/.env.example apps/frontend/.env

docker compose up -d --build

The access to the frontend using a web browser.

development

Even not necessary for Dockerized deployments, some dependencies are needed for development purpose:

• Node.js and npm.
• Nx.

Applications can be deployed for development purposes as follows:

npm i

# serve api
nx serve api

# serve frontend
nx serve frontend

applications documentation

Please refer to api and frontend README files.