Allow specifying primary and witness peers for the light clients

[romac]

Summary

We need to be able to somehow configure the primary and witness peers for the light client of a given chain.

Problem Definition

Spawning a light client requires providing both a primary peer and one or more witness peers.
We currently do not track this information, and thus point both the primary and a single witness to the same node.
We need a way of specifying the primary and its witnesses via the command line.

Proposal

Add new subcommands to the light command which will allow us to manage the primary and witness peers for a chain's light client. I propose the following API:

USAGE:
    relayer-cli light peer <OPTIONS>

DESCRIPTION:
    configure the peers of the light client for a given chain

SUBCOMMANDS:
    add       add a peer to the light client configuration
    rm        remove a peer from the light client configuration

USAGE:
    relayer-cli light peer add <OPTIONS>

DESCRIPTION:
    add a peer to the light client of a given chain

POSITIONAL ARGUMENTS:
    chain_id                  identifier of the chain

FLAGS:
    -a, --address ADDRESS     network address of the peer
    -i, --peer-id PEER_ID     identifier of the peer
    -p, --primary             make this peer the primary peer

USAGE:
    relayer-cli light peer rm <OPTIONS>

DESCRIPTION:
    remove a peer from the light client of a given chain

POSITIONAL ARGUMENTS:
    chain_id                  identifier of the chain

FLAGS:
    -i, --peer-id PEER_ID     identifier of the peer to remove

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[romac]

One question I have is where should those be stored?

a) in the light_config.toml file, just like the trust options
b) in the relayer config file

If we go with b), perhaps we should also merge the light_config.toml into the relayer config file?

[ancazamfir]

One question I have is where should those be stored?

a) in the light_config.toml file, just like the trust options
b) in the relayer config file

If we go with b), perhaps we should also merge the light_config.toml into the relayer config file?

I would prefer b) and add any required light client options to the the relayer config file. It includes some today already. Could you please add a link to a full light client config as reference?

[romac]

Could you please add a link to a full light client config as reference?

It's currently just a map from ChainId to TrustOptions: https://github.com/informalsystems/ibc-rs/blob/master/relayer-cli/src/light/config.rs

[ancazamfir]

I was asking about the tendermint-rs light client config.

[romac]

Here is the config file we use for the light node: https://github.com/informalsystems/tendermint-rs/blob/master/light-node/light_node.toml.example

[ancazamfir]

We have a similar issue in #99, should we close that?

[romac]

Let's keep both issues, we'll do the configs merge first and then we can tackle the CLI for editing it.

[romac]

Done in #348