IBC Relayer Setup Guide
Babylon uses IBC (Inter-Blockchain Communication protocol) to enable cross-chain communication. To support this capability it relies on relayers, processes that can be run by anyone which constantly scan for outbound packets on one chain and submits these packets alongside corresponding proofs on the destination chain. This section describes how one can setup a relayer and create new connections between chains.
There are two standard implementations:
- Hermes built in Rust
- Go Relayer built in Go
The following guide explains how to establish IBC connections and relay packets between Celestia Mocha testnet and Babylon testnet networks by using the Hermes relayer.
Hermes
Hermes is an open-source Rust implementation of an IBC relayer released as part of the ibc-relayer-cli crate. It includes a CLI for relaying packets between Cosmos SDK chains, as well as Prometheus metrics and a REST API.
Prerequisites
Please follow the steps at Hermes Quick Start to install Hermes.
Before proceeding, verify that Hermes is installed correctly by running hermes version.
Configuration
Prerequisites
- Funded Celestia Mocha account
- Funded Babylon testnet account
To acquire testnet tokens for Celestia Mocha, use Celestia Testnet Faucet bot. To get testnet tokens for Babylon testnet, use Babylon Genesis Testnet Faucet.
Configure the chains
After installing Hermes, create .hermes folder in your $HOME directory and create a config file.
mkdir $HOME/.hermes
Copy config.toml file from the hermes repository to the .hermes folder.
cp $HOME/hermes/config.toml $HOME/.hermes/config.toml
For this tutorial, we will be using the following chains:
- Celestia's mocha-4 testnet
- Babylon's Phase 2 testnet
Edit the Hermes configuration.
vim $HOME/.hermes/config.toml
[global]
log_level = "info"
[mode.clients]
enabled = true
refresh = true
misbehaviour = true
[mode.connections]
enabled = false
[mode.channels]
enabled = false
[mode.packets]
enabled = true
clear_interval = 100
clear_on_start = true
tx_confirmation = false
auto_register_counterparty_payee = false
[rest]
enabled = false
host = "127.0.0.1"
port = 3000
[telemetry]
enabled = false
host = "127.0.0.1"
port = 3001
[telemetry.buckets.latency_submitted]
start = 500
end = 20000
buckets = 10
[telemetry.buckets.latency_confirmed]
start = 1000
end = 30000
buckets = 10
[[chains]]
id = 'bbn-test-5'
type = "CosmosSdk"
rpc_addr = 'https://babylon-testnet-rpc.nodes.guru'
grpc_addr = 'https://babylon-testnet-grpc.nodes.guru'
rpc_timeout = "10s"
trusted_node = false
account_prefix = "bbn"
key_name = "babylon"
key_store_type = "Test"
store_prefix = "ibc"
default_gas = 100000
max_gas = 4000000
gas_multiplier = 1.1
max_msg_num = 30
max_tx_size = 180000
max_grpc_decoding_size = 33554432
clock_drift = "5s"
max_block_time = "30s"
ccv_consumer_chain = false
memo_prefix = ""
sequential_batch_tx = false
[chains.event_source]
mode = "push"
url = "wss://babylon-testnet-rpc.nodes.guru/websocket"
batch_delay = "500ms"
[chains.trust_threshold]
numerator = "1"
denominator = "3"
[chains.gas_price]
price = 0.01
denom = "ubbn"
[chains.packet_filter]
policy = "allow"
list = [["transfer","channel-20"]]
[chains.packet_filter.min_fees]
[chains.address_type]
derivation = "cosmos"
[[chains]]
id = "mocha-4"
type = "CosmosSdk"
rpc_addr = "https://rpc-celestia-mocha.architectnodes.com"
grpc_addr = "https://grpc.celestia-mocha.com:443"
rpc_timeout = "10s"
trusted_node = false
account_prefix = "celestia"
key_name = "celestia-key"
key_store_type = "Test"
store_prefix = "ibc"
default_gas = 100000
max_gas = 400000
gas_multiplier = 1.5
max_msg_num = 30
max_tx_size = 180000
max_grpc_decoding_size = 33554432
clock_drift = "5s"
max_block_time = "30s"
ccv_consumer_chain = false
memo_prefix = ""
sequential_batch_tx = false
[chains.event_source]
mode = "push"
url = "ws://rpc-mocha.pops.one:26657/websocket"
batch_delay = "500ms"
[chains.trust_threshold]
numerator = "1"
denominator = "3"
[chains.gas_price]
price = 0.1
denom = "utia"
[chains.packet_filter]
policy = "allow"
list = [["transfer", "channel-0"]]
[chains.packet_filter.min_fees]
[chains.address_type]
derivation = "cosmos"
Create/Add relayer wallets
Now that we have successfully configured our relaying chains, we need to import the wallets that will be used for relaying. Please note that both wallets need to be funded with the native tokens of each chain.
You can use Keplr to create a wallet for Celestia Mocha and Babylon testnet. You can get testnet tokens from faucets for bot testnets via Discord: Celestia: https://discord.gg/celestiacommunity Cosmos Hub: https://discord.gg/cosmosnetwork
Add your seed phrase to a .mnemonic file and upload it to the server. Do not use wallets for anything else but relaying to avoid running into account sequence errors.
Follow the steps at Adding Keys to Hermes to add keys for each chain:
hermes keys add --chain bbn-test-5 --mnemonic-file <PATH_TO_MNEMONIC_FILE>
hermes keys add --chain mocha-4 --mnemonic-file <PATH_TO_MNEMONIC_FILE>
Verify configuration files
After editing config.toml and adding wallet keys, run the health check:
hermes health-check
hermes config validate
If everything was set up correctly, you should see output like:
SUCCESS performed health check for all chains in the config
SUCCESS "configuration is valid"
Create clients
First, verify that the chains do not have existing clients:
hermes query clients --host-chain mocha-4 --reference-chain bbn-test-5
To create a new client, use the create-client command:
hermes create client --host-chain mocha-4 --reference-chain bbn-test-5
You should see output like:
SUCCESS CreateClient(
CreateClient(
Attributes {
client_id: ClientId(
"07-tendermint-27",
),
client_type: Tendermint,
consensus_height: Height {
revision: 4,
height: 5730919,
},
},
),
)
Make sure that accounts on both chains are funded with the native tokens of each chain. Otherwise, you will get an error:
ERROR foreign client error: error raised while creating client for chain mocha-4
Create a second client:
hermes create client --host-chain bbn-test-5 --reference-chain mocha-4
Create a connection
To create a connection between the two clients run:
hermes create connection --host-chain mocha-4 --reference-chain bbn-test-5
You should see output like:
SUCCESS Connection {
delay_period: 0ns,
a_side: ConnectionSide {
chain: BaseChainHandle {
chain_id: ChainId {
id: "mocha-4",
version: 4,
},
runtime_sender: Sender { .. },
},
client_id: ClientId(
"07-tendermint-595",
),
connection_id: Some(
ConnectionId(
"connection-654",
),
),
},
b_side: ConnectionSide {
chain: BaseChainHandle {
chain_id: ChainId {
id: "bbn-test-5",
version: 5,
},
runtime_sender: Sender { .. },
},
client_id: ClientId(
"07-tendermint-29",
),
connection_id: Some(
ConnectionId(
"connection-27",
),
),
},
}
Now that the connection has been established over the clients, we need to create a new channel using an existing connection:
hermes create channel --a-chain mocha-4 --a-connection connection-654 --a-port transfer --b-port transfer
You should see output like:
SUCCESS Channel {
ordering: Unordered,
a_side: ChannelSide {
chain: BaseChainHandle {
chain_id: ChainId {
id: "mocha-4",
version: 4,
},
runtime_sender: Sender { .. },
},
client_id: ClientId(
"07-tendermint-595",
),
connection_id: ConnectionId(
"connection-654",
),
port_id: PortId(
"transfer",
),
channel_id: Some(
ChannelId(
"channel-389",
),
),
version: None,
},
b_side: ChannelSide {
chain: BaseChainHandle {
chain_id: ChainId {
id: "bbn-test-5",
version: 5,
},
runtime_sender: Sender { .. },
},
client_id: ClientId(
"07-tendermint-29",
),
connection_id: ConnectionId(
"connection-27",
),
port_id: PortId(
"transfer",
),
channel_id: Some(
ChannelId(
"channel-20",
),
),
version: None,
},
connection_delay: 0ns,
Configure channels in Hermes
Now that we have created new connections and opened channels, we need to edit config.toml again and add the newly created channels, or use the already existing ones.
For mocha-4 add:
[chains.packet_filter]
policy = "allow"
list = [["transfer", "channel-389"]]
For bbn-test-5 add:
[chains.packet_filter]
policy = "allow"
list = [["transfer","channel-20"]]
Start the relayer
Start the relayer via hermes start
hermes start