docs: deviation from cosmos relay (#129)

Co-authored-by: izyak <[email protected]>
Co-authored-by: viveksharmapoudel <[email protected]>

README.md

@@ -13,6 +13,14 @@
 [![codecov](https://codecov.io/gh/icon-project/ibc-relay/branch/main/graph/badge.svg?token=3OSG4KPSPZ)](https://codecov.io/gh/icon-project/ibc-relay)
 </div>
 
+---
+
+This repo is a fork of cosmos [relayer](https://github.com/cosmos/relayer). The goal of this project is to relay packets between ICON and Wasm chains by following the IBC Specs. 
+1. [What is ICON-IBC Integration](https://github.com/icon-project/IBC-Integration)
+2. [Deviations from Cosmos Relayer](./docs/deviations_from_ibc.md)
+---
+
+
 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](https://ibcprotocol.org/) enabled chains.
 The relayer submits these updates in the form of specific message types to the counterparty chain. Clients are then used to 

docs/deviations_from_ibc.md

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+# Deviations from IBC Relay
+
+This relayer was meant to be used for [ICON-IBC Integration](https://github.com/icon-project/IBC-Integration). So, it is made to accomodate all the changes made on IBC Integration such that IBC can be established between ICON and Cosmos based chains.
+
+All the deviations that the ICON-IBC Integrations can be found [here]().
+
+## Changes 
+The major changes in the relayer include: 
+- [ICON Module](#icon-module)
+- [Wasm Module](#wasm-module)
+- [Relayer Internal](#relayer-internal)
+- [Cmd](#cmd)
+- [Config](#config)
+
+## Icon Module
+- Icon Chain Module has been added to support ICON Chain.
+- We use [BTP Blocks](https://icon.community/glossary/btp-blocks/) provided by ICON chain significantly.
+- Icon provides a websocket api which we can use to stream all blocks of mainnet. We do use this websockets instead of polling each height as done on cosmos chain processor.
+- The relayer interfaces with IBC contract deployed on ICON and calls methods of the contract via ICON Provider.
+- To update counterparty light client, we use information obtained BTP Blocks rather than actual main ICON chain.
+- We query if the block is a BTP Block, and if yes, it initiates messages that'll be sent to counterparty contract. So, for each BTP Block produced, light client is updated.
+
+## Wasm Module
+- Wasm Module has been added to support CosmWasm contracts.
+- Like cosmos chain processor, polling is done for each height of the chain.
+- Wasm Provider provides methods to interface with the IBC Wasm contract deployed on respective cosmos chain.
+
+## Relayer Internal
+- Minimal changes has had to be added on the internal logic of the relayer to support for BTP Blocks.
+- Since ICON cannot produce non membership proofs via BTP Blocks, a method called `requestTimeout` was introduced on ICON contract for when packet is to be timed out on wasm contracts. Logic for this has been added on relayer internal.
+- Update client and the message to be sent after, has been sent on different transaction. [Reason for this decision]()
+
+## Cmd
+- Relevant methods for ICON has been added accordingly.
+- When a BTP client is to be created on WASM contract, we need to specify a BTP height for the relayer. By default, it takes the first BTP height for this network. If we are to give a custom height, a flag `btp-block-height` has been added. The height should be a BTP Block for given BTP network type and BTP Network Id.
+    ```sh
+    rly tx clients icon-path-name --client-tp "1000000m"  --btp-block-height 11313986
+    ```
+
+## Config
+- Example Config for ICON-IBC Integration
+    - [Here](../examples/config_IBC_ICON.yaml)
+
+
+
+## Wasm Config
+Other parameters are same as in cosmos chains. The specifications for added fields in config are
+- IBC Handler Address
+    - WASM Contract Address of IBC Handler
+- First Retry Block After:
+    - For first retry transaction, wait for this number of blocks (default set to 3)
+- Start Height:
+    - Custom height to start chain processor from
+- Block Interval:
+    - Block Interval of cosmos chain
+
+## Icon Config
+- keystore and password
+    - Keystore and password is used to generate a wallet for relay
+- Icon Network ID
+    - Network ID for ICON chain (varies for testnet, localnet and mainnet)
+- BTP Network ID, BTP Network Type ID
+    - BTP Specific IDs required 
+- Start Height:
+    - Height to start ICON chain processor from
+- IBC Handler Address:
+    - Address of IBC java contract
+- Block Interval:
+    - Block Interval of ICON chain
+- First Retry Block After:
+    - For first retry transaction, wait for this number of blocks (default set to 8)

examples/config_IBC_ICON.yaml

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+global:
+    api-listen-addr: :5183
+    timeout: 10s
+    memo: ""
+    light-cache-size: 20
+chains:
+    archway:
+        type: wasm
+        value:
+            key-directory: /home/user/.relayer/keys/localnet
+            key: relayWallet
+            chain-id: localnet
+            rpc-addr: http://localhost:26657
+            account-prefix: archway
+            keyring-backend: test
+            gas-adjustment: 1.5
+            gas-prices: 0.025stake
+            min-gas-amount: 1000000
+            debug: true
+            timeout: 20s
+            block-timeout: ""
+            output-format: json
+            sign-mode: direct
+            extra-codecs: []
+            coin-type: 0
+            broadcast-mode: batch
+            ibc-handler-address: archway14hj2tavq8fpesdwxxcu44rty3hh90vhujrvcmstl4zr3txmfvw9sy85n2u
+            first-retry-block-after: 0
+            start-height: 0
+            block-interval: 6000
+    icon:
+        type: icon
+        value:
+            key: ""
+            chain-id: ibc-icon
+            rpc-addr: http://localhost:9082/api/v3/
+            timeout: 30s
+            keystore: /home/user/keystore/godWallet.json
+            password: gochain
+            icon-network-id: 3
+            btp-network-id: 1
+            btp-network-type-id: 1
+            start-height: 0
+            ibc-handler-address: cxa1daa337788364a72644860a5097e3eef7a5d416
+            first-retry-block-after: 0
+            block-interval: 2000
+paths:
+    icon-archway:
+        src:
+            chain-id: ibc-icon
+            client-id: 07-tendermint-0
+            connection-id: connection-0
+        dst:
+            chain-id: localnet
+            client-id: iconclient-0
+            connection-id: connection-0
+        src-channel-filter:
+            rule: ""
+            channel-list: []