---
tags: Demi
---
# 4/3 Mainnet forking
## Agenda
1. Mainnet forking
2. Full node vs Full archive node
3. 範例
## Mainnet forking
在本地的開發網路中模擬跟主網相同的狀態
讓開發者能夠在本地端與部屬中的合約做複雜的測試互動

## Full Node vs Archive Node
1. 歸檔節點 Archive nodes - Has data since genesis block.
2. 全節點 Full nodes - Receive copies of transactions. Has the current state of the blockchain.
3. Light nodes- Doesn’t have the entirety of the current blockchain state and depends on a full node, useful for low memory and computational devices.
4. Miner nodes - Miner nodes verify transactions and add them to the blocks. They then mine those blocks and secure the blockchain with proof of work.

Hardware requirements to run a full node with fast sync:

A fast Cpu with 4+ cores.
16 GB+ of RAM.
A fast SSD drive with at least **500GB+** of space.
25 MBit/s+ bandwidth.

Hardware requirements to run a full archive node:

A fast Cpu with 4+ cores.
16 GB+ of RAM.
A fast SSD drive with at least **6TB+** of space.
25 MBit/s+ bandwidth.
### Provider
1. QuickNode https://www.quicknode.com/
2. **Alchemy** https://www.alchemy.com/
3. **Moralis** https://moralis.io/

## Let's start
### 安裝hardhat
https://hardhat.org/getting-started/#installation
https://www.youtube.com/watch?v=S0DFNvJu4TQ

### Environment setup

$ mkdir hardhat_fork
$ cd hardhat_fork

$ yarn init # 沒有想更動的部分，就按 Enter 鍵帶過即可
...
$ yarn add dotenv@16.0.0
$ yarn add hardhat@2.8.4
$ yarn add @nomiclabs/hardhat-waffle@2.0.2
$ yarn add @nomiclabs/hardhat-web3@2.0.0
$ yarn add @nomiclabs/hardhat-ethers@2.0.5
$ yarn add web3@1.7.0
$ yarn add ethers@5.5.4

$ yarn hardhat
▸ Create an empty hardhat.config.js # 請選擇這個選項，並按 Enter

### 調整 config
1. 輸入 Alchemy_key
hardhat_fork/.env

Mainnet = "https://eth-mainnet.alchemyapi.io/v2/<your_Alchemy_key>"

2.
hardhat_fork/hardhat.config.js

require("@nomiclabs/hardhat-waffle");
require("@nomiclabs/hardhat-web3");
require("@nomiclabs/hardhat-ethers");
require('dotenv').config();

task("height", "Print the current block height")
  .setAction(async (taskArgs) => {
    const block_height = await web3.eth.getBlockNumber();
    console.log(`The current block height is ${block_height}`);
  });

module.exports = {
  networks: {
    hardhat: {
      forking: {
        url: process.env.Mainnet,
        blockNumber: 14297759
      }
    }
  }
};
// 高度 14297759 發生在 2022-03-01 00:00:18 (UTC+0)，選擇此數字方便後續解說

### 使用自定義的 Hardhat task
1. 列出所有可用的 Hardhat task

$ yarn hardhat --network "hardhat" help
yarn run v1.22.17
Hardhat version 2.8.4

Usage: hardhat [GLOBAL OPTIONS] <TASK> [TASK OPTIONS]

GLOBAL OPTIONS:
  --config              A Hardhat config file.
  --emoji               Use emoji in messages.
  --help                Shows this message, or a task's help if its name is provided
  --max-memory          The maximum amount of memory that Hardhat can use.
  --network             The network to connect to.
  --show-stack-traces   Show stack traces.
  --tsconfig            A TypeScript config file.
  --verbose             Enables Hardhat verbose logging
  --version             Shows hardhat's version.

AVAILABLE TASKS:
  check         Check whatever you need
  clean         Clears the cache and deletes all artifacts
  compile       Compiles the entire project, building all artifacts
  console       Opens a hardhat console
  flatten       Flattens and prints contracts and their dependencies
  height        Print the current block height
  help          Prints this message
  node          Starts a JSON-RPC server on top of Hardhat Network
  run           Runs a user-defined script after compiling the project
  test          Runs mocha tests

2. 運行 height 指令

$ yarn hardhat --network "hardhat" height
yarn run v1.22.17
The current block height is 14297759

3. 利用 node 指令，開始運作 Hardhat Network 節點

$ yarn hardhat --network "hardhat" node

## 範例一：與 WETH9 合約互動
https://gist.github.com/a2468834/6101244f5000e467ec8904ac5f0ec41d

WETH9 合約
https://etherscan.io/address/0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2#code
將合約 ABI 儲存到 hardhat_fork/scripts/contract-abi.json

### 範例二：抓取 public 變數的歷史數據
https://gist.github.com/a2468834/71c59d580c1da21337350cdfc47e515b

## 參考資料來源:
1. Chuan-Chun Wang - Hardhat mainnet forking：主網分叉 (1) https://lundao.tech/blog/hardhat-forking-1/
2. Chuan-Chun Wang Hardhat mainnet forking：主網分叉 (2) https://lundao.tech/blog/hardhat-forking-2
3. Hardhat - Mainnet forking
https://hardhat.org/hardhat-network/guides/mainnet-forking.html
3. Moralis - Connect to BSC Node https://docs.moralis.io/speedy-nodes/connecting-to-rpc-nodes/connect-to-bsc-node
4. QuickNode - Ethereum full node vs archive node https://www.quicknode.com/guides/infrastructure/ethereum-full-node-vs-archive-node
## 清交區塊鏈 DAO
https://discord.gg/Uh9QyZCcuv
Blockchain and DeFi Study Group
built with Demi-Chubbytank, Demi-Rabbit, CCWang and other NTHU/NCTU students

## 無情業配
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