lightning-utxopsbt.json

{
  "$schema": "../rpc-schema-draft.json",
  "type": "object",
  "rpc": "utxopsbt",
  "title": "Command to populate PSBT inputs from given UTXOs",
  "description": [
    "*utxopsbt* is a low-level RPC command which creates a PSBT using unreserved inputs in the wallet, optionally reserving them as well.",
    "",
    "It deliberately mirrors the parameters and output of lightning-fundpsbt(7) except instead of an optional *minconf* parameter to select unreserved outputs from the wallet, it takes a compulsory list of outputs to use."
  ],
  "request": {
    "required": [
      "satoshi",
      "feerate",
      "startweight",
      "utxos"
    ],
    "additionalProperties": false,
    "properties": {
      "satoshi": {
        "type": "sat_or_all",
        "description": [
          "The minimum satoshi value of the output(s) needed (or the string `all` meaning use all unreserved inputs). If a value, 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*."
        ]
      },
      "feerate": {
        "type": "feerate",
        "description": [
          "Used for the transaction as initial feerate."
        ],
        "default": "*normal*"
      },
      "startweight": {
        "type": "u32",
        "description": [
          "The weight of the transaction before *fundpsbt* has added any inputs."
        ]
      },
      "utxos": {
        "type": "array",
        "description": [
          "An array of `txid:vout`, each of which must be reserved or available."
        ],
        "items": {
          "type": "outpoint"
        }
      },
      "reserve": {
        "type": "u32",
        "description": [
          "If not zero, then *reserveinputs* is called (successfully, with *exclusive* true) on the returned PSBT for this number of blocks."
        ],
        "default": "72 blocks"
      },
      "reservedok": {
        "type": "boolean",
        "description": [
          "If set to true, it will also fail if any of the *utxos* are already reserved."
        ],
        "default": "false"
      },
      "locktime": {
        "type": "u32",
        "description": [
          "If not set, it is set to a recent block height."
        ]
      },
      "min_witness_weight": {
        "type": "u32",
        "description": [
          "Minimum weight to use for a UTXO's witness. If the actual witness weight is greater than the provided minimum, the actual witness weight will be used."
        ]
      },
      "excess_as_change": {
        "type": "boolean",
        "description": [
          "Flag to add a change output for the excess sats."
        ]
      },
      "opening_anchor_channel": {
        "added": "v23.08",
        "type": "boolean",
        "description": [
          "To signel that it needs emergency reserve for anchors so that we can lowball our commitment tx fees, and min-emergency-msat for reserving some sats for closing anchor channels."
        ]
      }
    }
  },
  "response": {
    "required": [
      "psbt",
      "feerate_per_kw",
      "estimated_final_weight",
      "excess_msat"
    ],
    "additionalProperties": false,
    "properties": {
      "psbt": {
        "type": "string",
        "description": [
          "Unsigned PSBT which fulfills the parameters given."
        ]
      },
      "feerate_per_kw": {
        "type": "u32",
        "description": [
          "The feerate used to create the PSBT, in satoshis-per-kiloweight."
        ]
      },
      "estimated_final_weight": {
        "type": "u32",
        "description": [
          "The estimated weight of the transaction once fully signed."
        ]
      },
      "excess_msat": {
        "type": "msat",
        "description": [
          "The amount above *satoshi* which is available. This could be zero, or dust; it will be zero if *change_outnum* is also returned."
        ]
      },
      "change_outnum": {
        "type": "u32",
        "description": [
          "The 0-based output number where change was placed (only if parameter *excess_as_change* was true and there was sufficient funds)."
        ]
      },
      "reservations": {
        "type": "array",
        "description": [
          "If *reserve* was true or a non-zero number, just as per lightning- reserveinputs(7)."
        ],
        "items": {
          "type": "object",
          "required": [
            "txid",
            "vout",
            "was_reserved",
            "reserved",
            "reserved_to_block"
          ],
          "additionalProperties": false,
          "properties": {
            "txid": {
              "type": "txid",
              "description": [
                "The txid of the transaction."
              ]
            },
            "vout": {
              "type": "u32",
              "description": [
                "The 0-based output number."
              ]
            },
            "was_reserved": {
              "type": "boolean",
              "description": [
                "Whether this output was previously reserved."
              ]
            },
            "reserved": {
              "type": "boolean",
              "enum": [
                true
              ],
              "description": [
                "Whether this output is now reserved."
              ]
            },
            "reserved_to_block": {
              "type": "u32",
              "description": [
                "The blockheight the reservation will expire."
              ]
            }
          }
        }
      }
    },
    "post_return_value_notes": [
      "On success, returns the *psbt* it created, containing the inputs, *feerate_per_kw* showing the exact numeric feerate it used, *estimated_final_weight* for the estimated weight of the transaction once fully signed, and *excess_msat* containing the amount above *satoshi* which is available. This could be zero, or dust. If *satoshi* was `all`, then *excess_msat* is the entire amount once fees are subtracted for the weights of the inputs and *startweight*.",
      "",
      "If *reserve* was *true* or a non-zero number, then a *reservations* array is returned, exactly like *reserveinputs*.",
      "",
      "If *excess_as_change* is true and the excess is enough to cover an additional output above the `dust_limit`, then an output is added to the PSBT for the excess amount. The *excess_msat* will be zero. A *change_outnum* will be returned with the index of the change output."
    ]
  },
  "errors": [
    "On error the returned object will contain `code` and `message` properties, with `code` being one of the following:",
    "",
    "- -32602: If the given parameters are wrong.",
    "- -1: Catchall nonspecific error.",
    "- 301: Insufficient UTXOs to meet *satoshi* value."
  ],
  "author": [
    "Rusty Russell <<rusty@rustcorp.com.au>> is mainly responsible."
  ],
  "see_also": [
    "lightning-fundpsbt(7)"
  ],
  "resources": [
    "Main web site: <https://github.com/ElementsProject/lightning>"
  ],
  "examples": [
    {
      "request": {
        "id": "example:utxopsbt#1",
        "method": "utxopsbt",
        "params": [
          1000000,
          "15000perkw",
          214,
          [
            "utxo010101010101010101010101010101010101010101010101010101010101:1"
          ],
          null,
          true,
          null,
          null,
          true
        ]
      },
      "response": {
        "psbt": "cHNidP8BAgQCAAAAAQMEbwAAAAEEAQpsbt510000510000510000510000510000510000510000510000510000510000510000510000510000510000510000510000510000510000510000510000510000510000510000510000510000510000510000510000510000510000510000510000510000510000510000510000510000510000510000510000",
        "feerate_per_kw": 15000,
        "estimated_final_weight": 657,
        "excess_msat": 0,
        "change_outnum": 0,
        "reservations": [
          {
            "txid": "utxo010101010101010101010101010101010101010101010101010101010101",
            "vout": 1,
            "was_reserved": true,
            "reserved": true,
            "reserved_to_block": 2240
          }
        ]
      }
    },
    {
      "request": {
        "id": "example:utxopsbt#2",
        "method": "utxopsbt",
        "params": {
          "satoshi": 2000000,
          "feerate": "18750perkw",
          "startweight": 214,
          "utxos": [
            "utxo010101010101010101010101010101010101010101010101010101010101:1"
          ],
          "reservedok": true,
          "excess_as_change": true
        }
      },
      "response": {
        "psbt": "cHNidP8BAgQCAAAAAQMEbwAAAAEEAQpsbt520000520000520000520000520000520000520000520000520000520000520000520000520000520000520000520000520000520000520000520000520000520000520000520000520000520000520000520000520000520000520000520000520000520000520000520000520000520000520000520000",
        "feerate_per_kw": 18750,
        "estimated_final_weight": 657,
        "excess_msat": 0,
        "change_outnum": 0,
        "reservations": [
          {
            "txid": "utxo010101010101010101010101010101010101010101010101010101010101",
            "vout": 1,
            "was_reserved": true,
            "reserved": true,
            "reserved_to_block": 2312
          }
        ]
      }
    }
  ]
}