LNCDaemonized

This is a Golang daemon that exposes lnc methods through a REST-like API, serving as a server-side alternative to lnc-web.

Currently, it supports only the lnrpc.Lightning methods and checkPerms. Additional methods can be easily registered in lncd.go.

Lifecycle of LNC connections is managed. Connections are reused whenever possible and are automatically terminated after a period of inactivity.

Configuration options can be specified via environment variables (all are optional):

Environment Variable	Default Value	Description
LNCD_TIMEOUT	5m	Timeout duration for connections.
LNCD_LIMIT_ACTIVE_CONNECTIONS	210	Maximum number of active connections allowed.
LNCD_STATS_INTERVAL	1m	Interval for logging connection pool statistics.
LNCD_DEBUG	false	Flag to enable or disable debug logging.
LNCD_PORT	7167	Port on which the server listens.
LNCD_HOST	0.0.0.0	Host address on which the server listens.
LNCD_TLS_CERT_PATH	""	Path to the TLS certificate file (empty to disable TLS).
LNCD_TLS_KEY_PATH	""	Path to the TLS key file (empty to disable TLS).
LNCD_AUTH_TOKEN	""	Bearer token required to access the server (empty to disable authentication).
LNCD_DEV_UNSAFE_LOG	false	Enable or disable logging of sensitive data.
LNCD_HEALTHCHECK_SERVICE_PORT	7168	Additional healthcheck service port.
LNCD_HEALTHCHECK_SERVICE_HOST	127.0.0.1	Additional healthcheck service host.

If LNCD_HEALTHCHECK_SERVICE_PORT and LNCD_HEALTHCHECK_SERVICE_HOST are set, an additional unauthenticated and unencrypted healthcheck endpoint will be listening on the specified port and host.

Intended scope

This was developed to serve as the backend for stacker.news' LNC receive attachments. It has only been tested with the lnrpc.Lightning.AddInvoice method, so if you plan to use this as a general-purpose LNC connector, ensure you test and review it accurately.

Usage example

You can test the commands below using the web ui at http://localhost:7167/ or by sending POST requests to http://localhost:7167/rpc

POST /rpc
{
    "Connection":{
        "Mailbox": "mailbox.terminal.lightning.today:443",
        "PairingPhrase": "...."        
    },
	"Method": "checkPerms"
	"Payload": "[\"lnrpc.Lightning.AddInvoice\", \"lnrpc.Lightning.SendPaymentSync\"]" 
}

RESPONSE 
{
  "Connection": {
    "Mailbox": "mailbox.terminal.lightning.today:443",
    "PairingPhrase": "...",
    "LocalKey": "...", // put this back into the next request to reuse the same pairing phrase
    "RemoteKey": "...", // put this back into the next request to reuse the same pairing phrase
    "Status": "Connected"
  },
  "Result": "[true,false]"
}

POST /rpc
{
    "Connection":{
        "Mailbox": "mailbox.terminal.lightning.today:443",
        "PairingPhrase": "...."        
    },
	"Method": "lnrpc.Lightning.AddInvoice"
	"Payload": "{\"memo\":\"test\",\"valueMsat\":1000}"
}


RESPONSE
{
  "Connection": {
    "Mailbox": "mailbox.terminal.lightning.today:443",
    "PairingPhrase": "...",
    "LocalKey": "...", // put this back into the next request to reuse the same pairing phrase
    "RemoteKey": "...", // put this back into the next request to reuse the same pairing phrase
    "Status": "Connected"
  },
  "Result": "{\"r_hash\":\"xx\", \"payment_request\":\"xx\", \"add_index\":\"x\", \"payment_addr\":\"xx\"}"
}

Endpoints

• POST http://localhost:7167/rpc : Send a request and get a response from the LNC server.
• GET http://localhost:7167/ : Web UI to test the /rpc endpoint.
• GET http://localhost:7167/health : Health check endpoint.
• GET http://localhost:7168/health : Unauthenticated health check endpoint (if enabled).