Client

Table of Contents

• Create Client
• Update Client

Create Client

Use the create client command to create a new client on a destination chain, tracking the state of the source chain.

DESCRIPTION:
Create a new IBC client

USAGE:
    hermes create client [OPTIONS] --host-chain <HOST_CHAIN_ID> --reference-chain <REFERENCE_CHAIN_ID>

OPTIONS:
        --clock-drift <CLOCK_DRIFT>
            The maximum allowed clock drift for this client.
            
            The clock drift is a correction parameter. It helps deal with clocks that are only
            approximately synchronized between the source and destination chains of this client. The
            destination chain for this client uses the clock drift parameter when deciding to accept
            or reject a new header (originating from the source chain) for this client. If this
            option is not specified, a suitable clock drift value is derived from the chain
            configurations.

    -h, --help
            Print help information

        --trust-threshold <TRUST_THRESHOLD>
            Override the trust threshold specified in the configuration.
            
            The trust threshold defines what fraction of the total voting power of a known and
            trusted validator set is sufficient for a commit to be accepted going forward.

        --trusting-period <TRUSTING_PERIOD>
            Override the trusting period specified in the config.
            
            The trusting period specifies how long a validator set is trusted for (must be shorter
            than the chain's unbonding period).

REQUIRED:
        --host-chain <HOST_CHAIN_ID>
            Identifier of the chain that hosts the client

        --reference-chain <REFERENCE_CHAIN_ID>
            Identifier of the chain targeted by the client

Example

Create a new client on ibc-0 which tracks ibc-1:

hermes create client --host-chain ibc-0 --reference-chain ibc-1

    CreateClient(
        Attributes {
            height: Height {
                revision: 0,
                height: 286,
            },
            client_id: ClientId(
                "07-tendermint-0",
            ),
            client_type: Tendermint,
            consensus_height: Height {
                revision: 1,
                height: 274,
            },
        },
    ),
)

A new client is created with identifier 07-tendermint-1

Update Client

Use the update client command to update an existing client with a new consensus state. Specific update and trusted heights can be specified.

DESCRIPTION:
Update an IBC client

USAGE:
    hermes update client [OPTIONS] --host-chain <HOST_CHAIN_ID> --client <CLIENT_ID>

OPTIONS:
        --archive-address <ARCHIVE_ADDRESS>
            The RPC address of the archive node to use to fetch headers from before the restart.
            Requires --restart-height if used. [aliases: archive-addr]

    -h, --help
            Print help information

        --height <REFERENCE_HEIGHT>
            The target height of the client update. Leave unspecified for latest height.

        --restart-height <RESTART_HEIGHT>
            The height that the chain underwent a genesis restart at. Requires --archive-address if
            used.

        --trusted-height <REFERENCE_TRUSTED_HEIGHT>
            The trusted height of the client update. Leave unspecified for latest height.

REQUIRED:
        --client <CLIENT_ID>            Identifier of the client to update
        --host-chain <HOST_CHAIN_ID>    Identifier of the chain that hosts the client

Update client with latest header

the client on ibc-0 with the latest header of ibc-1:

hermes update client --host-chain ibc-0 --client 07-tendermint-9

Success: UpdateClient(
    UpdateClient {
        common: Attributes {
            height: Height { revision: 0, height: 303 },
            client_id: ClientId(
                "07-tendermint-1",
            ),
            client_type: Tendermint,
            consensus_height: Height { revision: 1, height: 293 },
        },
        header: Some(
            Tendermint(
                 Header {...},
            ),
        ),
    },
)

The client with identifier 07-tendermint-1 has been updated with the consensus state at height 1-293.

Update a client to a specific target height

hermes update client --height 320 --trusted-height 293 --host-chain ibc-0 --client 07-tendermint-1

Success: UpdateClient(
    UpdateClient {
        common: Attributes {
            height: Height { revision: 0, height: 555 },
            client_id: ClientId(
                "07-tendermint-1",
            ),
            client_type: Tendermint,
            consensus_height: Height { revision: 1, height: 320 },
        },
        header: Some(
            Tendermint(
                 Header {...},
            ),
        ),
    },
)

The client with identifier 07-tendermint-1 has been updated with the consensus state at height 1-320, as specified.