IBC Solo Machine

This repository implements IBC solo machine which can be used to interface with other machines & replicated ledgers which speak IBC.

Building

To build solo-machine binary, run: cargo build --package solo-machine.

Usage

Solo machine CLI has following sub-commands:

solo-machine-cli 0.1.0
A command line interface for IBC solo machine

USAGE:
    solo-machine [FLAGS] [OPTIONS] <SUBCOMMAND>

FLAGS:
    -h, --help        Prints help information
        --no-style    Does not print styled/colored statements
    -V, --version     Prints version information

OPTIONS:
        --db-uri <db-uri>         Database connection string [example: `sqlite://solo-machine.db`] [env: SOLO_DB_URI]
        --handler <handler>...    Register an event handler. Multiple event handlers can be registered and they're
                                  executed in order they're provided in CLI. Also, if an event handler returns an error
                                  when handling a message, all the future event handlers will not get executed
        --signer <signer>         Register a signer (path to signer's `*.so` file) [env: SOLO_SIGNER]

SUBCOMMANDS:
    chain             Chain operations (managing chain state and metadata)
    gen-completion    Generate completion scripts for solo-machine-cli
    help              Prints this message or the help of the given subcommand(s)
    ibc               Used to connect, mint tokens and burn tokens on IBC enabled chain
    init              Initializes database for solo machine
    start             Starts gRPC server for solo machine

• chain sub-command is used to manage an IBC enabled chain's state and metadata on solo machine, for example, its gRPC address, fee configuration, etc.
• ibc sub-command is used to broadcast IBC related transactions to cosmos SDK chain. This includes connect, mint (mint tokens on cosmos SDK chain) and burn (burn tokens on cosmos SDK chain).

Other than these three core commands,

• init is used to initialize SQLite database at given location.
• start is used to start a gRPC server which has endpoints for all the above three core functions.
• gen-completion generates autocompletion scripts for different shells.

In addition to these sub-commands, solo machine also has some configuration options which can either be provided using command line options, environment variables or in a .env file.

Connecting to a Cosmos SDK chain

To connect to a cosmos SDK chain, we first need an account on cosmos SDK chain with enough tokens so that it can pay transaction fee for IBC transactions.

1. Create a .env file with SOLO_DB_URI, SOLO_SIGNER and all the values needed by signer provided. For example, MnemonicSigner expects SOLO_MNEMONIC, SOLO_HD_PATH, SOLO_ACCOUNT_PREFIX and SOLO_ADDRESS_ALGO environment variables.
2. Run solo-machine init to initialize SQLite database.
3. Add cosmos SDK chain details using solo-machine chain add. This command takes following options which can either be provided using command line options, environment variables or a .env file. The two most important things are trusted-height and trusted-hash which can be fetched from: curl http://<ip>:<port>/block?height=<trusted-height>.

``` solo-machine-chain-add 0.1.0 Adds metadata for new IBC enabled chain

USAGE: solo-machine chain add [OPTIONS] --trusted-hash --trusted-height

FLAGS: -h, --help Prints help information -V, --version Prints version information

OPTIONS: --diversifier Diversifier used in transactions for chain [env: SOLO_DIVERSIFIER] [default: solo-machine-diversifier] --fee-amount Fee amount [env: SOLO_FEE_AMOUNT] [default: 1000] --fee-denom Fee denom [env: SOLO_FEE_DENOM] [default: stake] --gas-limit Gas limit [env: SOLO_GAS_LIMIT] [default: 300000] --grpc-addr gRPC address of IBC enabled chain [env: SOLO_GRPC_ADDRESS] [default: http://0.0.0.0:9090] --max-clock-drift Maximum clock drift [env: SOLO_MAX_CLOCK_DRIFT] [default: 3 sec] --port-id Port ID used to create connection with chain [env: SOLO_PORT_ID] [default: transfer] --rpc-addr RPC address of IBC enabled chain [env: SOLO_RPC_ADDRESS] [default: http://0.0.0.0:26657] --rpc-timeout RPC timeout duration [env: SOLO_RPC_TIMEOUT] [default: 60 sec] --trust-level Trust level (e.g. 1/3) [env: SOLO_TRUST_LEVEL] [default: 1/3] --trusted-hash Block hash at trusted height of the chain [env: SOLO_TRUSTED_HASH] --trusted-height Trusted height of the chain [env: SOLO_TRUSTED_HEIGHT] --trusting-period Trusting period [env: SOLO_TRUSTING_PERIOD] [default: 14 days] ```

1. Establish IBC connection with the chain using solo-machine ibc connect <chain-id>.
2. Mint tokens on cosmos SDK chain using solo-machine ibc mint <chain-id> <amount> <denom>.
3. Burn some tokens on cosmos SDK chain using solo-machine ibc burn <chain-id> <amount> <denom>. Note that the denom in burn command will be the denom on solo machine and not the IBC denom (ibc/XXX).

Connecting to Ethermint

If you wish to connect to ethermint using solo machine, you'll have to enable ethermint feature when building: cargo build --package solo-machine --features ethermint and also provide SOLO_ADDRESS_ALGO="eth-secp256k1" in .env file if you're using native eth-secp256k1 addresses on ethermint.

Use PostgreSQL instead of SQLite

If you wish to use PostgreSQL instead of SQLite, you'll have to enable postgres feature when building: cargo build --features postgres and provide SOLO_DB_URI in below format:

postgresql://[user[:password]@][host][:port][/dbname]

Signers

Solo machine supports adding a transaction signer at runtime using dynamic libraries (dylib). To create a new signer, the dynamic library should expose a function named register_signer with signature:

fn register_signer(registrar: &mut dyn SignerRegistrar) -> anyhow::Result<()>

The implementation of register_signer can call registrar.register() and pass a Arced object of Signer. A sample signer can be found here and can be used as a template to develop more complex signers.

Note that in Cargo.toml, we have to add following lines to make it a dynamic library.

[lib]
crate-type = ["dylib"]

Once implemented, the library can be compiled to *.so file and supplied to solo machine using --signer CLI option or SOLO_SIGNER environment variable.

For example,

solo-machine --signer="<path-to-dylib-.so-file>" ibc <chain-id> mint 100 gld

Event hooks

Solo machine supports adding event hooks at runtime using dynamic libraries (dylib). To create a new event hook, the dynamic library should expose a function named register_handler with signature:

fn register_handler(registrar: &mut dyn HandlerRegistrar)

The implementation of register_handler can call registrar.register() and pass a Boxed object of EventHandler. A sample event hook can be found here and can be used as a template to develop more complex event hooks.

Note that in Cargo.toml, we have to add following lines to make it a dynamic library.

[lib]
crate-type = ["dylib"]

Once implemented, the library can be compiled to *.so file and supplied to solo machine using --handler CLI option.

For example,

solo-machine --handler="<path-to-dylib-.so-file>" ibc <chain-id> mint 100 gld

All the events that can be generated by solo machine can be found here.

License

Licensed under Apache License, Version 2.0 (LICENSE).

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be licensed as above, without any additional terms or conditions.