IBC Relayer

For IBC protocol overview, refer to

Overview

Relayers are permissionless off-chain processes that ferry data packets from one chain to another. Relayer (opens in a new tab)s scan chain states, build transactions based on these states, and submit the transactions to the chains involved in the network. Relayers play a crucial role in IBC because chains do not directly send messages to each other over networking infrastructure. Instead, they create and store the data to be retrieved and used by a relayer to build IBC packets.

Get an in-depth walkthrough of the IBC components and packet flow on the developer documentation. (opens in a new tab)

There are several relayer implementations in different languages:

Golang relayer (opens in a new tab)
Rust hermes (opens in a new tab)

Running relayer with Sei

Installation

We will be using hermes as example relayer. Please note, that Sei requires hermes of version 1.3.0 .

To install hermes simply head to the GitHub Releases (opens in a new tab) page and download Hermes binary matching your platform:

macOS: hermes-v1.3.0-x86_64-apple-darwin.tar.gz (or .zip),
Linux: hermes-v1.3.0-x86_64-unknown-linux-gnu.tar.gz (or .zip).

The step-by-step instruction below should carry you through the whole process:

Make the directory where we'll place the binary:


mkdir -p $HOME/.hermes/bin

Extract the binary archive:


tar -C $HOME/.hermes/bin/ -vxzf $ARCHIVE_NAME

Update your path, by adding this line in your .bashrc or .zshrc shell configuration file:


export PATH="$HOME/.hermes/bin:$PATH"

The Source code archive (opens in a new tab) also contains hermes documentation that you can follow in guide/book folder.

Configuration

$HOME/.hermes/config.toml file should look like below. Please note that this example assumes local chains, so all RPC urls have to be substituted for real chain ones.

[global]
log_level = 'info'
 
[mode]
 
[mode.clients]
enabled = true
refresh = true
misbehaviour = true
 
[mode.connections]
enabled = true
 
[mode.channels]
enabled = true
 
[mode.packets]
enabled = true
clear_interval = 100
clear_on_start = true
tx_confirmation = true
 
[telemetry]
enabled = true
host = '127.0.0.1'
port = 3001
 
[[chains]]
id = 'ibc-0'
rpc_addr = 'http://localhost:27030'
grpc_addr = 'http://localhost:27032'
rpc_timeout = '15s'
account_prefix = 'cosmos'
key_name = 'wallet'
store_prefix = 'ibc'
gas_price = { price = 0.01, denom = 'stake' }
max_gas = 10000000
gas_multiplier = 1.5
clock_drift = '5s'
trusting_period = '14days'
trust_threshold = { numerator = '1', denominator = '3' }
event_source = { mode = 'push', url = 'ws://127.0.0.1:27030/websocket', batch_delay = '500ms' }
 
[[chains]]
id = 'sei-chain'
rpc_addr = 'http://localhost:26657'
grpc_addr = 'http://localhost:9090'
rpc_timeout = '15s'
account_prefix = 'sei'
key_name = 'wallet'
store_prefix = 'ibc'
gas_price = { price = 0.025, denom = 'usei' }
max_gas = 10000000
gas_multiplier = 2
clock_drift = '5s'
trusting_period = '14days'
trust_threshold = { numerator = '1', denominator = '3' }
event_source = { mode = 'push', url = 'ws://127.0.0.1:26657/websocket', batch_delay = '500ms' }

Next we need to add the account keys to hermes.

 
$ hermes keys add --key-name wallet --chain sei-chain --mnemonic-file ~/misc/mm_file_sei
$ hermes keys add --key-name wallet --chain ibc-0 --mnemonic-file ~/misc/mm_file_ibc_0

The contents of ~/misc/mm_file_* file is just a seed phrase of the chain account that will be associated with the chain.

Finally we need to create clients, connections and channel. There are separate commands for that, but there is a simpler shortcut command:

$ hermes create channel --a-chain sei-chain --b-chain ibc-0 --a-port transfer --b-port transfer --new-client-connection

The output of this command should return created channel details.

Finally start relaying:

$ hermes start

Please note, that this tutorial is a simplified version. Running relayer in production would require different level of effort, configuration and monitoring.

For more information on hermes, please refer to the official 1.3 version documentation (opens in a new tab) that can be found in the guide/book folder of the source code archive.

Proposals Differences from Ethereum