IBC Relayer in TypeScript

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Typescript implementation of an IBC Relayer.
To get a good overview of what it can do, please check our feature matrix
You can also read our specification page, which explains how the relayer works, but the Quick Start probably gives a better intro.
This repo is mainly used as a node binary to perform IBC relaying. However, all logic is available in the library, which can be run equally well in the browser or in Node. You can see an example of embedding the relayer in a webapp below.


Important Note

Versions until v0.1.6 support Cosmos SDK v0.41.1+. From v0.2.0 on we require Tendermint v0.34.9+ (which is used in SDK v0.42.4+). If you are connecting to a v0.41 chain, please use the v0.1.x relayer.
With v0.2.0 we add support for relaying packets in BeginBlock and EndBlock. However, this requires an extra rpc endpoint in Tendermint that is not available in v0.41.1. We therefore increase the minimum compatible version of the SDK.



Install the latest release.
npm i -g @confio/relayer

Alternatively, install from the main branch.
npm i -g @confio/relayer@main

NOTE: We do a manual release after completing a predefined milestone or when it feels right. No release schedule is in place yet. To utilize the latest changes, use the main tag during the installation.


After installation, ibc-setup and ibc-relayer executables are available.


Collection of commands to quickly setup a relayer and query IBC/chain data.


Reads the configuration and starts relaying packets.

Quick start

Configure and start the relayer

  1. Init the configuration
ibc-setup init --src malaga --dest uni

- creates relayer's home directory at `~/.ibc-setup`
- creates `app.yaml` inside relayer's home with `src`, `dest` and newly generated `mnemonic`
- pulls default `registry.yaml` to relayer's home
- funds addresses on `malaga` so relayer can pay the fee while relaying packets

> **NOTE:** Both testnets are running in the public. You do not need to start any blockchain locally to complete the quick start guide.

> **NOTE:** Run `ibc-setup balances` to see the amount of tokens on each address.
  1. Get testnet tokens for uni
- Find your relayer address on uni via: `ibc-setup keys list | grep uni`
- Join Juno discord with [this invite link](https://discord.gg/NbB8zCPX)
- Go to the `faucet` channel
- Request tokens at this address in the above channel: `$request iaa1fxmqew9dgg44jdf3l34zwa8rx7tcf42wz8ehjk`
- Check you have tokens on malaga and uni via `ibc-setup balances`

See [original instructions](https://docs.junonetwork.io/validators/joining-the-testnets#get-some-testnet-tokens)
  1. Create ics20 channel
ibc-setup ics20 -v

- creates a new connection on source and desination chains
- saves connection ids to `app.yaml` file
- creates a new channel
  1. Start the relayer in the verbose mode and 10s frequency polling
ibc-relayer start -v --poll 15

Send tokens between chains

  1. Make sure wasmd binary is installed on your system
- you must be running Linux or OSX on amd64 (not arm64/Mac M1)
- [install Go 1.17+](https://golang.org/doc/install) and ensure that `$PATH` includes Go binaries (you may need to restart your terminal session)
- clone and install `wasmd`:
  git clone https://github.com/CosmWasm/wasmd.git
  cd wasmd
  git checkout v0.27.0
  make install
  1. Make sure juno binary is installed on your system
- you must be running Linux or OSX on amd64
- [install Go 1.17+](https://golang.org/doc/install) and ensure that `$PATH` includes Go binaries (you may need to restart your terminal session)
- clone and install `juno`:
  git clone https://github.com/CosmosContracts/juno
  cd juno
  git checkout v6.0.0
  make install
  1. Create a new account and fund it
wasmd keys add sender
JSON=$(jq -n --arg addr $(wasmd keys show -a sender) '{"denom":"usponge","address":$addr}')
curl -X POST --header "Content-Type: application/json" --data "$JSON" https://faucet.malaga.cosmwasm.com/credit
  1. Create a valid IRISnet address to send tokens to
junod keys add receiver

[Get testnet tokens](https://docs.junonetwork.io/validators/joining-the-testnets#get-some-testnet-tokens) if you want to send tokens to `malaga`.
  1. Send tokens
wasmd tx ibc-transfer transfer transfer <channel-id> $(junod keys show -a receiver) 200usponge --from $(wasmd keys show -a sender) --node http://rpc.malaga.cosmwasm.com:80 --chain-id malaga-1 --fees 2000usponge --packet-timeout-height 0-0
- replace `<channel-id>` with the channel id obtained while configuring the relayer (2nd point)
- if you cleared out the terminal, query the channel
  ibc-setup channels --chain malaga
  1. Observe the relayer output

Configuration overview

The relayer configuration is stored under relayer's home directory. By default, it's located at $HOME/.ibc-setup, however, can be customized with home option, e.g.:
# initialize the configuration at /home/user/relayer_custom_home
ibc-setup init --home /home/user/relayer_custom_home

# read the configuration from /home/user/relayer_custom_home
ibc-relayer start --home /home/user/relayer_custom_home

There are 3 files that live in the relayer's home.
  • registry.yaml (required)

Contains a list of available chains with corresponding information. The chains from the registry can be referenced by ibc-setup binary or within the app.yaml file. View an example of registry.yaml file.
  • app.yaml (optional)

Holds the relayer-specific options such as source or destination chains. These options can be overridden with CLI flags or environment variables.
  • last-queried-heights.json (optional)

Stores last queried heights for better performance on relayer startup. It's constantly overwritten with new heights when relayer is running. Simply delete this file to scan the events since forever.
Learn more about configuration.


The relayer collects various metrics that a Prometheus instance can consume.
To enable metrics collection, pass the --enable-metrics flag when starting the relayer:
ibc-relayer start --enable-metrics

NOTE: Metrics can also be enabled via an environment variable RELAYER_ENABLE_METRICS=true, or with an enableMetrics: true entry in the app.yaml file, as explained in the config specification.

The GET /metrics endpoint will be exposed by default on port 8080, which you can override with --metrics-port flag, RELAYER_METRICS_PORT env variable, or metricsPort entry in app.yaml.

Local setup


  1. Start the relayer with metrics enabled
  2. Spin up the Prometheus instance:
docker run -it -v $(pwd):/prometheus -p9090:9090 prom/prometheus --config.file=demo/prometheus.yaml
> **NOTE:** Ensure that `the --config.file=<path>` flag points at the existing configuration file. If you wish to use [the example config](demo/prometheus.yaml), just run the command above in the root of this repository. Otherwise, you must adjust the volume (`-v`) and config file path to your setup.
  1. Open the Prometheus dashboard in a browser at http://localhost:9090


  1. Spin up the Grafana instance:
docker run -d --name=grafana -p 3000:3000 grafana/grafana
  1. Navigate to http://localhost:3000 and log in (admin/admin)
  2. Create a Prometheus data source
> **NOTE:** Use `http://host.docker.internal:9090` as the server URL and `Server` as the Access method.
  1. Create a new graph and query data
> **NOTE:** Useful guides:
- https://grafana.com/docs/grafana/latest/getting-started/getting-started/#step-3-create-a-dashboard
- https://prometheus.io/docs/visualization/grafana/#creating-a-prometheus-graph


Refer to the development page.

Integration Tests

ts-relayer can be used as a library as well as a binary. This allows us to make powerful node scripts, or to easily test CosmWasm contract IBC flows in CI code. You can look at the following two examples on how to do so:

Chain Requirements

The blockchain must be based on Cosmos SDK v0.42.4+. In particular it must have PR 8458 and PR 9081 merged (if you are using a fork) in order for the relayer to work properly. ibc-setup should work on v0.40.0+
The chain must have a large value for staking.params.historical_entries (often set in genesis). The default is "10000" and this should work with "1000", but no relayer will work if it is set to 0.

Full Node Requirements

Ideally you are in control of the node that the relayer connects to. If not, it should be run by a known and trusted party, whom you can check the configuration with. Note that a malicious node could cause the relayer to send invalid packets and waste tokens on gas (but not create invalid state).
The indexer should be enabled (tx_index.indexer = "kv" in config.toml), and all events should be indexed (index-events = [] in app.toml).
The node must support historical queries. --pruning=nothing will definitely work, but will use an enormous amount of disk space. You can also trim it to 3 weeks of data with --pruning=custom --pruning-keep-recent=362880 --pruning-keep-every=0 --pruning-interval=100, which has been tested. It is likely you could reduce pruning-keep-recent to as low as, say, 3600, but that would need testing.

Web App

This repo can also be imported as a library and used in a web app. @clockworkgr has been so nice to share a sample Vue.js app using the relayer. This includes some nice code samples to send a IbcTransfer message with CosmJS as well as setting up and running the relayer.
The key import is import { IbcClient, Link } from "@confio/relayer/build";