lndk/docs/cli_commands.md

Interacting with LNDK server

There are two ways you can connect to the server:

• You can use lndk-cli to connect to a running instance of LNDK and pay an offer.
• Write a gRPC client in the language of your choice.

lndk-cli installation

To use the lndk-cli to pay a BOLT 12 offer, follow these instructions:

• To install lndk-cli: cargo install --bin=lndk-cli --path .
• With the above command, lndk-cli will be installed to ~/.cargo/bin. So make sure ~/.cargo/bin is on your PATH so we can properly run lndk-cli.
• Run lndk-cli -h to make sure it's working. You'll see output similar to:

A cli for interacting with lndk

Usage: lndk-cli [OPTIONS] <COMMAND>

Commands:
  decode-offer    Decodes a bech32-encoded offer string into a BOLT 12 offer
  decode-invoice  Decodes a hex-encoded invoice string into a BOLT 12 invoice
  pay-offer       PayOffer pays a BOLT 12 offer, provided as a 'lno'-prefaced offer string
  get-invoice     GetInvoice fetch a BOLT 12 invoice, which will be returned as a hex-encoded string. It fetches the invoice from a BOLT 12 offer, provided as a 'lno'-prefaced offer string
  pay-invoice     PayInvoice pays a hex-encoded BOLT12 invoice
  create-offer    CreateOffer creates a BOLT 12 offer
  help            Print this message or the help of the given subcommand(s)

Options:
  -n, --network <NETWORK>              Global variables [default: regtest]
  -m, --macaroon-path <MACAROON_PATH>  Option for passing a file path to a macaroon file obtained from LND node. Either this option or macaroon_hex must be set, there is no default
      --macaroon-hex <MACAROON_HEX>    A hex-encoded macaroon string to pass in directly to the cli to authenticate with LND node. Either this option or macaroon_path must be set, there is no default
      --cert-pem <CERT_PEM>            This option is for passing a pem-encoded TLS certificate string to establish a connection with the LNDK server. If this isn't set, the cli will look for the TLS file in the default location (~.lndk/data). Only one of cert_pem or cert_path can be set at once
      --cert-path <CERT_PATH>          This option is for passing a file path to a pem-encoded TLS certificate string to establish a connection with the LNDK server. If this isn't set, the cli will look for the TLS file in the default location (~.lndk/data). Only one of cert_pem or cert_path can be set at once
      --grpc-host <GRPC_HOST>          Host of the LNDK server [default: https://127.0.0.1]
      --grpc-port <GRPC_PORT>          Port of the LNDK server [default: 7000]
  -h, --help                           Print help

lndk-cli commands

Once lndk-cli is installed, you can use it to pay an offer.

Since lndk-cli needs to connect to lnd, you'll need to provide an lnd macaroon to the binary.

If your macaroon is not in the default lnd location, you'll need to specify them manually.

If your macaroon is in the default location, paying an offer looks like:

lndk-cli pay-offer <OFFER_STRING> <AMOUNT_MSATS>

If your macaroon is not in the default location, an example command looks like:

lndk-cli --network=mainnet --macaroon-path=/credentials/custom.macaroon pay-offer <OFFER_STRING> <AMOUNT_MSATS>

Or you can pass in the credentials directly with a macaroon string like: lndk-cli --network=mainnet --macaroon-hex=<MACAROON_HEX_STR> pay-offer <OFFER_STRING> <AMOUNT_MSATS>

Creating an offer

To create a BOLT 12 offer with default settings:

lndk-cli create-offer --amount <AMOUNT_MSATS> --description "a nice description"

To create an offer with additional options:

lndk-cli create-offer --amount <AMOUNT_MSATS> --description "a nice description" --issuer "ACME-inc" --expiry 3600 --quantity 5

If your macaroon is not in the default location:

lndk-cli --network=mainnet --macaroon-path=/credentials/custom.macaroon create-offer --amount <AMOUNT_MSATS> --description "cool description"

gRPC client example

Another option for interacting with LNDK is to connect to the LNDK server with a gRPC client, which you can do in most languages.

Again, since LNDK needs to connect to LND, you'll need to pass in your LND macaroon to establish a connection. Note that:

• The client must pass in this data via gRPC metadata. You can find an example of this in the Rust client used to connect lndk-cli to the server.

Baking a custom macaroon

Rather than use the admin.macaroon with unrestricted permission to an LND node, we can bake a macaroon using lncli with much more specific permissions for better security. Note also that the macaroon required for starting up a LNDK instance requires different permissions than when making a payment.

When using pay-offer, you can generate a macaroon which will give LNDK only the specific grpc endpoints it needs to hit:

lncli bakemacaroon --save_to=<FILEPATH>/lndk-pay.macaroon uri:/walletrpc.WalletKit/DeriveKey uri:/signrpc.Signer/SignMessage uri:/lnrpc.Lightning/GetNodeInfo uri:/lnrpc.Lightning/ConnectPeer uri:/lnrpc.Lightning/GetInfo uri:/lnrpc.Lightning/ListPeers uri:/lnrpc.Lightning/GetChanInfo uri:/lnrpc.Lightning/QueryRoutes uri:/routerrpc.Router/SendToRouteV2 uri:/routerrpc.Router/TrackPaymentV2

If you're using just the get-invoice command, you can bake a macaroon with less permissions:

lncli bakemacaroon --save_to=<FILEPATH>/lndk-pay.macaroon uri:/walletrpc.WalletKit/DeriveKey uri:/signrpc.Signer/SignMessage uri:/lnrpc.Lightning/GetNodeInfo uri:/lnrpc.Lightning/ConnectPeer uri:/lnrpc.Lightning/GetInfo uri:/lnrpc.Lightning/ListPeers uri:/lnrpc.Lightning/GetChanInfo

TLS: Running lndk-cli remotely

When LNDK is started up, self-signed TLS credentials are automatically generated and stored in ~/.lndk or your --data-dir <PATH> configured. If you're running lndk-cli locally, it'll know where to find the certificate file it needs to establish a secure connection with the LNDK server.

To run lndk-cli on a remote machine, users need to copy the tls-cert.pem file to the corresponding LNDK data directory on the machine where lndk-cli is being run.