Bot Plutus Interface

NOTE: This library has been deprecated and is no longer being actively developed by MLabs.

This is a custom implementation of the PAB as the official one is not ready yet. This PAB is not feature complete, and not fully tested with all use cases, so please use it with care!

Disclaimer: this project is still a work in progress, with a few missing features. We don't take any responsibility for any losses, only use it at your own risk!

Supported features:

• query utxos at an address (utxosAt)
• evaluate Contract (not all features implemented, see the rest of this list for details)
• pre balance tx (adding minimum amount of tx inputs based on fee and tx output value, balancing non ada outputs)
• mint tokens, and send them to arbitrary address(es)
• redeem utxos from validator scripts, using the correct datum and redeemer (scripts, datums and redeemers are persisted in files for now)
• use validity time ranges
• waiting for slots

Unsupported/In development

• wallet integration
• handling on-chain events (utxo set change, etc.)

How to use this?

Wiring up your own contract is pretty much the same as with the official PAB:

1. Define your endpoints for the PAB

data MyContracts
  = Send SendParams
  | Collect CollectParams
  deriving stock
    (Show, Generic)
  deriving anyclass
    (FromJSON, ToJSON)

2. Define a HasDefinitions instance for the endpoints

import BotPlutusInterface.Types (HasDefinitions (..), SomeBuiltin (..), endpointsToSchemas)
import Playground.Types (FunctionSchema)
import Schema (FormSchema)

instance HasDefinitions MyContracts where
  getDefinitions :: [MyContract]
  getDefinitions = []

  getSchema :: MyContracts -> [FunctionSchema FormSchema]
  getSchema = \case
    Send _ -> endpointsToSchemas @MyContractSchema
    Collect _ -> endpointsToSchemas @MyContractSchema

  getContract :: (MyContracts -> SomeBuiltin)
  getContract = \case
    Send params ->
      SomeBuiltin $
        MyContract.contract params
    Collect params ->
      SomeBuiltin $
        MyContract.contract params

3. Write your main entrypoint for the application and the configuration file

import Prelude

main :: IO ()
main = do
  pabConf <-
    either error id
      <$> BotPlutusInterface.loadPABConfig "./pabConfig.value"
  BotPlutusInterface.runPAB @MyContracts pabConf

Configuration format (example: <examples/plutus-game/pabConfig.value>):

$ cabal repl --disable-optimisation --repl-options -Wwarn
...
BotPlutusInterface> :m Prelude
...
Prelude> :l BotPlutusInterface.Config
...
Prelude BotPlutusInterface.Config> putStrLn docPABConfig
Top-level configuration file fields:
    cliLocation: `local` or destination text
        calling the cli through ssh when set to destination (default:
        local)
    chainIndexUrl: url text
         (default: "http://localhost:9083")
    networkId: case insensitive `mainnet` atom or 32-bit unsigned integral number
         (default: 42)
    scriptFileDir: path text
        Directory name of the script and data files (default:
        "./result-scripts")
    signingKeyFileDir: path text
        Directory name of the signing key files (default: "./signing-keys")
    txFileDir: path text
        Directory name of the transaction files (default: "./txs")
    metadataDir: path text
        Directory name of metadata files (default: "/metadata")
    protocolParamsFile: filepath text
        Protocol params file location relative to the cardano-cli working
        directory (needed for the cli) in JSON format.  (default:
        "./protocol.json")
    dryRun: `true` or `false`
        Dry run mode will build the tx, but skip the submit step (default:
        true)
    logLevel: `error` or `warn` or `notice` or `info` or `debug`
         (default: info)
    ownPubKeyHash: PubKeyHash text
         (default: "")
    ownStakePubKeyHash: case insensitive `nothing` atom or StakePubKeyHash text
         (default: nothing)
    tipPollingInterval: non-negative integral number
         (default: 10000000)
    port: port non-negative integral number
         (default: 9080)
    enableTxEndpoint: `true` or `false`
         (default: false)
    collectStats: `true` or `false`
        Save some stats during contract run (only transactions execution
        budgets supported atm) (default: false)
    collectLogs: `true` or `false`
        Save logs from contract execution: pab request logs and contract
        logs (default: false)
    budgetMultiplier: rational multiplier in form `1` or `1 % 2`
         (default: 1)

To run the fake PAB, you need to prepare a few more things:

4. Save the protocol params file to the root folder of your project using the cardano-cli

cardano-cli query protocol-parameters --testnet-magic 42 --out-file protocol.json

5. Create a signing-keys folder under your projects root with the necessary signig key file(s). The files should be named in the following format: signing-key-PUBKEYHASHHEX.skey and verification-key-PUBKEYHASHHEX.vkey

Use the cardano-cli to find out the pub key hash for your key:

cardano-cli address key-hash --verification-key-file VERIFICATION_KEY.vkey

How does this work and how it is structured?

The fake PAB consists of the following modules:

• BotPlutusInterface main entry point
• BotPlutusInterface.Server Servant server, handling http endpoint calls and websockets
• BotPlutusInterface.Config load/save PAB configuration file
• BotPlutusInterface.Contract handling contract effects by creating the necessary files and calling cardano-cli commands (a few effects are mocked)
• BotPlutusInterface.Balance doing some preparations so the cli can process the rest (non-ada asset balancing, addig tx inputs, adding minimum lovelaces, add signatories)
• BotPlutusInterface.CardanoCLI wrappers for cardano-cli commands
• For development purposes, I created an ssh wrapper, so I can call relay these commands through an ssh connection. This is not nice, unsafe, and pretty slow, avoid using it if you can.
• BotPlutusInterface.UtxoParser parse the output of the cardano-cli query utxo command
• BotPlutusInterface.Files functions for handling script, datum and redeemer files
• BotPlutusInterface.Types configuration for the fake pab
• BotPlutusInterface.Balance prepare a transaction before sending to the cli for balancing. This includes:
  • adding tx inputs to cover fees and outputs
  • adding collaterals,
  • modifying tx outs to contain the minimum amount of lovelaces
  • balancing non ada outputs

Collateral handling

Current version handles collateral under the hood.

Before contract being executed, single transaction submitted to create collateral UTxO at "own" address. Default amount for collateral UTxO is 10 Ada. It also can be set via config.

BPI identifies collateral UTxO by its value. If "own" address already has UTxO with amount set in config, this UTxO will be used as collateral. UTxO that was picked as collateral is stored in memory, so each time BPI will use same UTxO for collateral. Also, collateral is not returned among other UTxOs inside Contract monad, e.g. from eDSL functions like utxosAt. So it is safe to use such functions without the risk of consuming collateral by accident.