Relayer Operator Guide

Relayer

In IBC, blockchains do not directly pass messages to each other over the network. This is where relayer comes in. A relayer process monitors for updates on opens paths between sets of IBC enabled chains. The relayer submits these updates in the form of specific message types to the counterparty chain. Clients are then used to track and verify the consensus state. In addition to relaying packets, this relayer can open paths across chains, thus creating clients, connections and channels. Additional information on how IBC works can be found here.

Table Of Contents

• Basic Usage - Relaying Across Chains

• Create Path Across Chains

• Advanced Usage

• Troubleshooting

• Features

• Relayer Terminology

• Recommended Pruning Settings

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Basic Usage - Relaying Packets Across Chains

The -h (help) flag tailing any rly command will be your best friend. USE THIS IN YOUR RELAYING JOURNEY.

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1. Clone, checkout and install the latest release (releases page). Go needs to be installed and a proper Go environment needs to be configured

   $ git clone https://github.com/ConsiderItDone/relayer.git
   $ cd relayer && git checkout main
   $ make install

2. Initialize the relayer's configuration directory/file.

   $ rly config init

   Default config file location: ~/.relayer/config/config.yaml By default, transactions will be relayed with a memo of rly(VERSION) e.g. rly(v2.5.2). To customize the memo for all relaying, use the --memo flag when initializing the configuration.

   $ rly config init --memo "My custom memo"

   Custom memos will have rly(VERSION) appended. For example, a memo of My custom memo running on relayer version v2.5.2 would result in a transaction memo of My custom memo | rly(v2.5.2). The --memo flag is also available for other rly commands also that involve sending transactions such as rly tx link and rly start. It can be passed there to override the config.yaml value if desired. To omit the memo entirely, including the default value of rly(VERSION), use - for the memo.

3. Configure the chains you want to relay between. In our example, we will configure the relayer to operate on the canonical path between the Cosmos Hub and Osmosis. The rly chains add command fetches chain meta-data from the chain-registry and adds it to your config file.

   $ rly chains add cosmoshub slide

   Adding chains from the chain-registry randomly selects an RPC address from the registry entry. If you are running your own node, manually go into the config and adjust the rpc-addr setting.

   NOTE: rly chains add will check the liveliness of the available RPC endpoints for that chain in the chain-registry. It is possible that the command will fail if none of these RPC endpoints are available. In this case, you will want to manually add the chain config. To add the chain config files manually, example config files have been included here

   $ rly chains add --url https://raw.githubusercontent.com/cosmos/relayer/main/docs/example-configs/cosmoshub-4.json cosmoshub

   Slide config example

   global:
    api-listen-addr: :5183
    timeout: 10s
    memo: ""
    light-cache-size: 20
    log-level: ""
    ics20-memo-limit: 0
    max-receiver-size: 0
   chains:
    slide:
        type: avalanche
        value:
            rpc-addr: http://127.0.0.1:9650/ext/bc/2qdf414xEdWsmjSK1Q59Gautq6fERXbXm4jJnJkZ6MfFBB6PaH/rpc
            base-rpc-addr: http://127.0.0.1:9650
            subnet-id: 2c1CbR7FGYdeFPB4WaeWphHZrChLH7TQ92FRW6U4mCWTnaxVsB
            blockchain-id: 2qdf414xEdWsmjSK1Q59Gautq6fERXbXm4jJnJkZ6MfFBB6PaH
            chain-id: "slide"
            network-id: 1337
            timeout: 10s
            contract-address: 0x0300000000000000000000000000000000000002
            transferrer-address: 0x17aB05351fC94a1a67Bf3f56DdbB941aE6c63E25
            key-directory: ~.relayer/keys/avalanche-slide
            key: testkey
            keyring-backend: test
            extra-codecs: []
            min-loop-duration: 0s
   ibcgo:
        type: cosmos
        value:
            key-directory: ~/.relayer/keys/ibcgo
            key: testkey
            chain-id: ibcgo
            rpc-addr: http://localhost:26657
            account-prefix: cosmos
            keyring-backend: test
            dynamic-gas-price: false
            gas-adjustment: 1.5
            gas-prices: 0.025stake
            min-gas-amount: 0
            max-gas-amount: 0
            debug: true
            timeout: 10s
            block-timeout: ""
            output-format: json
            sign-mode: direct
            extra-codecs: []
            coin-type: null
            signing-algorithm: ""
            broadcast-mode: batch
            min-loop-duration: 0s
            extension-options: []
            feegrants: null
   paths:
    demo:
        src:
            chain-id: slide
        dst:
            chain-id: ibcgo
        src-channel-filter:
            rule: ""
            channel-list: []
    demo2:
        src:
            chain-id: ibcgo
        dst:
            chain-id: slide
        src-channel-filter:
            rule: ""
            channel-list: []

4. Import OR create new keys for the relayer to use when signing and relaying transactions.

   key-name is an identifier of your choosing. If you need to generate a new private key you can use the add subcommand.

   $ rly keys add ibcgo [key-name]
   $ rly keys add slide [key-name]

   If you already have a private key and want to restore it from your mnemonic you can use the restore subcommand.

   $ rly keys restore ibcgo [key-name] "mnemonic words here"
   $ rly keys restore slide [key-name] "mnemonic words here"

5. Use the key-name created above.

   This step is necessary if you chose a key-name other than "default"

   $ rly keys use ibcgo [key-name]
   $ rly keys use slide [key-name]

6. Ensure the keys associated with the configured chains are funded.

   Your configured addresses will need to contain some of the respective native tokens for paying relayer fees.

   You can query the balance of each configured key by running:

   $ rly q balance ibcgo
   $ rly q balance slide

7. Configure path meta-data in config file. We have the chain meta-data configured, now we need path meta-data. For more info on path terminology visit here.

   NOTE: Thinking of chains in the config as "source" and "destination" can be confusing. Be aware that most path are bi-directional.

   rly paths fetch will check for IBC path meta data from the chain-registry and add these paths to your config file.

   $ rly paths fetch

   NOTE: Don't see the path metadata for paths you want to relay on? Please open a PR to add this metadata to the GitHub repo!

8. Configure the channel filter.

   By default, the relayer will relay packets over all channels on a given connection. Each path has a src-channel-filter which you can utilize to specify which channels you would like to relay on. The rule can be one of three values:

   • allowlist which tells the relayer to relay on ONLY the channels in channel-list

   • denylist which tells the relayer to relay on all channels BESIDES the channels in channel-list

   • empty value, which is the default setting, and tells the relayer to relay on all channels

   Since we are only worried about the canonical channel between the Cosmos Hub and Landslide our filter settings would look like the following. Example:

   hubslide:
      src:
          chain-id: ibcgo
          client-id: 07-tendermint-259
          connection-id: connection-257
      dst:
          chain-id: slide
          client-id: 14-avalanche-1
          connection-id: connection-1
      src-channel-filter:
              rule: allowlist
              channel-list: [channel-141]

   Because two channels between chains are tightly coupled, there is no need to specify the dst channels. If you only know the "dst" channel-ID you can query the "src" channel-ID by running: rly q channel <dst_chain_name> <dst_channel_id> <port> | jq '.channel.counterparty.channel_id'

9. Finally, we start the relayer on the desired path. The relayer will periodically update the clients and listen for IBC messages to relay.

   $ rly paths list
   $ rly start [path]
   # Optionally you can omit the `path` argument to start all configured paths
   $ rly start

   When running multiple instances of rly start, you will need to use the --debug-addr flag and provide an address:port. You can also pass an empty string '' to turn off this feature or pass localhost:0 to randomly select a port.

   [TROUBLESHOOTING]

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Create Path Across Chains -->