lightningd – Daemon for running a Lightning Network node¶
lightningd [--conf=<config-file>] [OPTIONS]…
lightningd starts the C-Lightning daemon, which implements a standards-compliant Lightning Network node.
–conf=FILE Specify configuration file. If not an absolute path, will be relative from the lightning-dir location. Defaults to config.
–lightning-dir=DIR Set the directory for the C-Lightning daemon. Defaults to $HOME/.lightning.
Command line options are mirrored as configuration options in the configuration file, so foo in the configuration file simply becomes –foo on the command line, and foo=bar becomes –foo=bar.
See lightningd-config(5) for a comprehensive list of all available options.
LOGGING AND COMMANDING C-LIGHTNING¶
By default, C-Lightning will log to the standard output. To log to a specific file, use –log-file=PATH. Sending SIGHUP will cause C-Lightning to reopen this file, for example to do log rotation.
C-Lightning will set up a Unix domain socket for receiving commands. By default this will be the file lightning-rpc in your specified lightning-dir. You can use lightning-cli(1) to send commands to C-Lightning once lightningd has started; you need to match the –lightning-dir and –rpc-file options between them.
Commands for C-Lightning are described in various manpages in section 7, with the common prefix lightning-.
First, decide on and create a directory for lightning-dir, or just use the default $HOME/.lightning. Then create a config file in this directory containing your configuration.
Your other main preparation would be to set up a mainnet Bitcoin fullnode, i.e. run a bitcoind(1) instance. The rest of this quick start guide will assume you are reckless and want to spend real funds on Lightning. Indicate network=bitcoin in your config file explicitly.
C-Lightning needs to communicate with the Bitcoin Core RPC. You can set this up using bitcoin-datadir, bitcoin-rpcconnect, bitcoin-rpcport, bitcoin-rpcuser, and bitcoin-rpcpassword options in your config file.
Finally, just to keep yourself sane, decide on a log file name and indicate it using log-file=lightningd.log in your config file. You might be interested in viewing it periodically as you follow along on this guide.
Once the bitcoind instance is running, start lightningd(8):
$ lightningd --lightning-dir=$HOME/.lightning --daemon
This starts lightningd in the background due to the –daemon option.
Check if things are working:
$ lightning-cli --lightning-dir=%HOME/.lightning help $ lightning-cli --lightning-dir=%HOME/.lightning getinfo
The getinfo command in particular will return a blockheight field, which indicates the block height to which lightningd has been synchronized to (this is separate from the block height that your bitcoind has been synchronized to, and will always lag behind bitcoind). You will have to wait until the blockheight has reached the actual blockheight of the Bitcoin network.
Before you can get funds offchain, you need to have some funds onchain owned by lightningd (which has a separate wallet from the bitcoind it connects to). Get an address for lightningd via lightning-newaddr(7) command as below (–lightning-dir option has been elided, specify it if you selected your own lightning-dir):
$ lightning-cli newaddr
This will provide a native SegWit bech32 address. In case all your money is in services that do not support native SegWit and have to use P2SH-wrapped addresses, instead use:
$ lightning-cli newaddr p2sh-segwit
Transfer a small amount of onchain funds to the given address. Check the status of all your funds (onchain and on-Lightning) via lightning-listfunds(7):
$ lightning-cli listfunds
Now you need to look for an arbitrary Lightning node to connect to, which you can do by using dig(1) and querying lseed.bitcoinstats.com:
$ dig lseed.bitcoinstats.com A
This will give 25 IPv4 addresses, you can select any one of those. You will also need to learn the corresponding public key, which you can determine by searching the IP addrss on https://1ml.com/ . The public key is a long hex string, like so: 024772ee4fa461febcef09d5869e1238f932861f57be7a6633048514e3f56644a1. (this example public key is not used as of this writing)
After determining a public key, use lightning-connect(7) to connect to that public key:
$ lightning-cli connect $PUBLICKEY
Then open a channel to that node using lightning-fundchannel(7):
$ lightning-cli fundchannel $PUBLICKEY $SATOSHI
This will require that the funding transaction be confirmed before you can send funds over Lightning. To track this, use lightning-listpeers(7) and look at the state of the channel:
$ lightning-cli listpeers $PUBLICKEY
The channel will initially start with a state of CHANNELD_AWAITING_LOCKIN. You need to wait for the channel state to become CHANNELD_NORMAL, meaning the funding transaction has been confirmed deeply.
Once the channel state is CHANNELD_NORMAL, you can start paying merchants over Lightning. Acquire a Lightning invoice from your favorite merchant, and use lightning-pay(7) to pay it:
$ lightning-cli pay $INVOICE
You should report bugs on our github issues page, and maybe submit a fix to gain our eternal gratitude!
lightning-listconfigs(7), lightning-config(5), lightning-cli(1), lightning-newaddr(7), lightning-listfunds(7), lightning-connect(7), lightning-fundchannel(7), lightning-listpeers(7), lightning-pay(7)
Note: the modules in the ccan/ directory have their own licenses, but the rest of the code is covered by the BSD-style MIT license.