LndHub.go

Wrapper for Lightning Network Daemon (lnd). It provides separate accounts with minimum trust for end users.

LndHub compatible API implemented in Go using relational database backends

• Using a relational database (PostgreSQL and SQLite)
• Focussing only on Lightning (no onchain functionality)
• No runtime dependencies (simple Go executable)

Status: WIP

Known Issues

• Currently no fee handling (users are currently not charged for lightning transaction fees)

Configuration

All required configuration is done with environment variables and a .env file can be used. Check the .env_example for an example.

cp .env_example .env
vim .env # edit your config

Available configuration

• DATABASE_URI: The URI for the database. If you want to use SQLite use for example: file:data.db
• JWT_SECRET: We use JWT for access tokens. Configure your secret here
• JWT_EXPIRY: How long the access tokens should be valid (in seconds)
• LND_ADDRESS: LND gRPC address (with port) (e.g. localhost:10009)
• LND_MACAROON_HEX: LND macaroon (hex)
• LND_CERT_HEX: LND certificate (hex)
• LOG_FILE_PATH: (optional) By default all logs are written to STDOUT. If you want to log to a file provide the log file path here
• SENTRY_DSN: (optional) Sentry DSN for exception tracking
• PORT: (default: 3000) Port the app should listen on

Developing

go run main.go

Building

To build an lndhub executable, run the following commands:

make

Database

LndHub.go supports PostgreSQL and SQLite as database backend. But SQLite does not support the same data consistency checks as PostgreSQL.

Ideas

• Using low level database constraints to prevent data inconsistencies
• Follow double-entry bookkeeping ideas (Every transaction is a debit of one account and a credit to another one)
• Support multiple database backends (PostgreSQL for production, SQLite for development and personal/friend setups)

Data model

                                                     ┌─────────────┐                            
                                                     │    User     │                            
                                                     └─────────────┘                            
                                                            │                                   
                                  ┌─────────────────┬───────┴─────────┬─────────────────┐       
                                  ▼                 ▼                 ▼                 ▼       
       Accounts:          ┌──────────────┐  ┌──────────────┐  ┌──────────────┐  ┌──────────────┐
                          │   Incoming   │  │   Current    │  │   Outgoing   │  │     Fees     │
       Every user has     └──────────────┘  └──────────────┘  └──────────────┘  └──────────────┘
       four accounts                                                                            
                                                                                                
                           Every Transaction Entry is associated to one debit account and one   
                                                    credit account                             
                                                                                                
                                                 ┌────────────────────────┐                     
                                                 │Transaction Entry       │                     
                                                 │                        │                     
                                                 │+ user_id               │                     
                   ┌────────────┐                │+ invoice_id            │                     
                   │  Invoice   │────────────────▶+ debit_account_id      │                     
                   └────────────┘                │+ credit_account_id     │                     
                                                 │+ amount                │                     
                  Invoice holds the              │+ ...                   │                     
                  lightning related              │                        │                     
                  data                           └────────────────────────┘