lightning-fundchannel – Command for establishing a lightning channel

SYNOPSIS

fundchannel id amount [feerate] [announce] [minconf] [utxos] [push_msat] [close_to]

DESCRIPTION

The fundchannel RPC command opens a payment channel with a peer by committing a funding transaction to the blockchain as defined in BOLT #2. If not already connected, fundchannel will automatically attempt to connect if C-lightning knows a way to contact the node (either from normal gossip, or from a previous connect call). This auto-connection can fail if C-lightning does not know how to contact the target node; see lightning-connect(7). Once the transaction is confirmed, normal channel operations may begin. Readiness is indicated by listpeers reporting a state of CHANNELD_NORMAL for the channel.

id is the peer id obtained from connect.

amount is the amount in satoshis taken from the internal wallet to fund the channel. The string all can be used to specify all available funds (or 16777215 satoshi if more is available and large channels were not negotiated with the peer). Otherwise, it is in satoshi precision; it can be a whole number, a whole number ending in sat, a whole number ending in 000msat, or a number with 1 to 8 decimal places ending in btc. The value cannot be less than the dust limit, currently set to 546, nor more than 16777215 satoshi (unless large channels were negotiated with the peer).

feerate is an optional feerate used for the opening transaction and as initial feerate for commitment and HTLC transactions. It can be one of the strings urgent (aim for next block), normal (next 4 blocks or so) or slow (next 100 blocks or so) to use lightningd’s internal estimates: normal is the default.

Otherwise, feerate is a number, with an optional suffix: perkw means the number is interpreted as satoshi-per-kilosipa (weight), and perkb means it is interpreted bitcoind-style as satoshi-per-kilobyte. Omitting the suffix is equivalent to perkb.

announce is an optional flag that triggers whether to announce this channel or not. Defaults to true. An unannounced channel is considered private.

minconf specifies the minimum number of confirmations that used outputs should have. Default is 1.

utxos specifies the utxos to be used to fund the channel, as an array of “txid:vout”.

push_msat is the amount of millisatoshis to push to the channel peer at open. Note that this is a gift to the peer – these satoshis are added to the initial balance of the peer at channel start and are largely unrecoverable once pushed.

close_to is a Bitcoin address to which the channel funds should be sent to on close. Only valid if both peers have negotiated option_upfront_shutdown_script. Returns close_to set to closing script iff is negotiated.

RETURN VALUE

On success, the tx and txid of the transaction is returned, as well as the outnum indicating the output index which creates the channel, as well as the channel_id of the newly created channel. On failure, an error is reported and the channel is not funded.

If a close_to address was provided, will close to this address iff the close_to script is returned in the response. Otherwise, the peer does not support option_upfront_shutdownscript.

The following error codes may occur:

  • -1: Catchall nonspecific error.

  • 300: The maximum allowed funding amount is exceeded.

  • 301: There are not enough funds in the internal wallet (including fees) to create the transaction.

  • 302: The output amount is too small, and would be considered dust.

  • 303: Broadcasting of the funding transaction failed, the internal call to bitcoin-cli returned with an error.

Failure may also occur if lightningd and the peer cannot agree on channel parameters (funding limits, channel reserves, fees, etc.).

SEE ALSO

lightning-connect(7), lightning-listfunds(), lightning-listpeers(7), lightning-feerates(7), lightning-multifundchannel(7)

RESOURCES

Main web site: https://github.com/ElementsProject/lightning