Relayer

The relayer package contains some basic relayer implementations that are meant to be used by users wishing to relay packets between IBC enabled chains. It is also well documented and intended as a place where users who are interested in building their own relayer can come for working examples.

Demoing the Relayer

While the relayer is under active development, it is meant primarily as a learning tool to better understand the Inter-Blockchain Communication (IBC) protocol. In that vein, the following demo demonstrates the core functionality which will remain even after the changes:

# ensure go is installed and GOPATH, GOBIN are set appropriately and GOBIN is in your PATH
# Documentation: https://golang.org/doc/install

# two-chainz creates two gaia-based chains with data directories in this 
$ ./two-chainz

# First initialize your configuration for the relayer
$ rly config init

# NOTE: you may want to look at the config between these steps to see
# what is added in each step. The config is located at ~/.relayer/config/config.yaml
$ cat ~/.relayer/config/config.yaml

# Then add the chains and paths that you will need to work with the 
# gaia chains spun up by the two-chains script
$ rly chains add -f demo/ibc0.json
$ rly chains add -f demo/ibc1.json

$ cat ~/.relayer/config/config.yaml

# To finalize your config, add a path between the two chains
$ rly paths add ibc0 ibc1 demo-path -f demo/path.json

# Now, add the key seeds from each chain to the relayer to give it funds to work with
$ rly keys restore ibc0 testkey "$(jq -r '.secret' data/ibc0/n0/gaiacli/key_seed.json)" -a
$ rly keys restore ibc1 testkey "$(jq -r '.secret' data/ibc1/n0/gaiacli/key_seed.json)" -a

# Then its time to initialize the relayer's lite clients for each chain
# All data moving forward is validated by these lite clients.
$ rly lite init ibc0 -f
$ rly lite init ibc1 -f

# At this point the relayer --home directory is ready for normal operations between 
# ibc0 and ibc1. Looking at the folder structure of the relayer at this point is helpful
$ tree ~/.relayer

# Now you can connect the two chains with one command:
$ rly tx full-path ibc0 ibc1

# Check the token balances on both chains
$ rly q balance ibc0
$ rly q balance ibc1

# Then send some tokens between the chains
$ rly tx transfer ibc0 ibc1 10000n0token true $(relayer keys show ibc1 testkey -a)

# See that the transfer has completed
$ rly q balance ibc0
$ rly q balance ibc1

# Send the tokens back to the account on ibc0
$ rly tx transfer ibc1 ibc0 10000n0token false $(relayer keys show ibc0 testkey -a)

# See that the return trip has completed
$ rly q balance ibc0
$ rly q balance ibc1

# NOTE: you will see the stake balances decreasing on each chain. This is to pay for fees
# You can change the amount of fees you are paying on each chain in the configuration.

NOTE: The relayer relies on cosmos/cosmos-sdk@ibc-alpha and tendermint/tendermint@v0.33.0-dev2. If you run into problems building it likely related to those dependancies. Also the two-chainz script requires that the cosmos/gaia and iqlusion/relayer repos be present locally and buildable. Read the script and change the paths as needed.

Next items

• Setup Versioning
• Split the xfer command into xfer-send and xfer-recv
• Wire up packet ack and timeout
• get naive relay strategy working properly

Setting up Developer Environment

Working with the relayer can frequently involve working with local developement branches of gaia, cosmos-sdk and the relayer. To setup your environment to point at the local versions of the code and reduce the amount of time in your read-eval-print loops try the following:

1. Set replace github.com/cosmos/cosmos-sdk => /path/to/local/github.com/comsos/cosmos-sdk at the end of the go.mod files for the relayer and gaia. This will force building from the local version of the cosmos-sdk when running the ./dev-env script.
2. After ./dev-env has run, you can use go run main.go for any relayer commands you are working on. This allows you make changes and immediately test them as long as there are no server side changes.
3. If you make changes in cosmos-sdk that need to be reflected server-side, be sure to re-run ./two-chainz.
4. If you need to work off of a gaia branch other than ibc-alpha, change the branch name at the top of the ./two-chainz script.