The Ultimate Ethereum Mainnet Deployment Guide
All you need to know to deploy to the Ethereum mainnet
We all love Ethereum, so you've built some great smart contracts. They are tested intensely with unit-tests and on testnets. Now it's finally time to go to mainnet. But this is a tricky business...
1. What exactly is a deployment transaction?
First let's quickly discuss what a contract deployment is on a low level. Any Ethereum transaction itself consists of only a few properties and there are generally three types of transactions:
- Sending Ether
- Deploying a smart contract
- Interacting with a smart contract
Some parts of a transaction are always the same for all three transactions: from, value, gas, gasPrice and nonce. The difference between them comes from the to and data parameter which stand for where the transaction is sent to and which data to send along with it.
- Sending Ether:
to: ETH receiver addressdata: empty (there's no smart contract involved here)- Deploying a smart contract
to: empty (we have no smart contract address yet, since we are only creating it just now)data: the bytecode of the smart contract (the result of compiling your smart contract)- Interacting with a smart contract
to: the smart contract addressdata: the function selector followed by the input data to the function
2. Considerations pre deployment
It should be no surprise by now that smart contract security is extremely important. And while you should follow best practices from the beginning, getting an audit before deploying to mainnet is the last and critical step. You can use https://www.smartcontractaudits.com/ to find a suitable auditor.
Secondly consider the security of your private keys. While for a testnet it's perfectly fine to just have a private key stored on your machine, this is not good enough for mainnet. Assuming you have some kind of access control, addresses with control over very critical aspects should be a multi-sig contract. This is its own smart contract which you can setup yourself. For example a 5 out of 7 multisig would require 5 addresses of a total of 7 to sign a transaction. You can use an app like Gnosis Safe to create one. And the private keys itself would all ideally be from hardware wallets like Ledger and Trezor.
3. How to do the actual deployment
In total what you'll need to deploy a contract is
- Your contract's bytecode – this is generated through compilation.
- A private key to an Ethereum address with enough ETH to pay for gas.
- A deployment tool or script.
- An Ethereum node service like Infura or QuikNode or simply by running your own node
Now there are some tools to help you with and I can tell you, some work better than others for mainnet.
a. Truffle
Truffle is still a very widely used tool especially for deployments. It can do many things from smart contract compilation to automated testing. But now we are interested in its migrations which are used for deployments.
Typical Truffle configuration
On the right you see a very typical truffle config. Here you can see how we solve a lot of the requirements for deploying a contract:
- Compilation: We define our solc version in the
compilerssection. Truffle will automatically compile our contracts before any deployments. - Private key: We use the hdwallet-provider to create a private key from a mnemonic. This is also a good option for mainnet. However, remember to change ownership of contracts after deployment to something more secure. Or use a Trezor or Ledger provider directly with some extra work.
- Infura: We pass our Infura endpoint here with our key. This can be changed to whatever endpoint service you're using or a url to your own node.
Migrations
The migrations are special scripts for you to define how to deploy a smart contract. This is particularly useful if you have multiple contracts to deploy which depend on each other or if you need to call functions on any contracts after the deployment.
Check out the migrations link here for the full documentation on how to use them.
require("dotenv").config();
const HDWalletProvider = require("@truffle/hdwallet-provider");
const { MNEMONIC, INFURA_API_KEY } = process.env;
const kovanUrl = `https://kovan.infura.io/v3/${INFURA_API_KEY}`;
const mainnetUrl = `https://mainnet.infura.io/v3/${INFURA_API_KEY}`;
module.exports = {
networks: {
development: {
host: "127.0.0.1",
port: 7545,
network_id: "*",
},
mainnet: {
provider: () => new HDWalletProvider(MNEMONIC, mainnetUrl),
network_id: 1,
},
kovan: {
provider: () => new HDWalletProvider(MNEMONIC, kovanUrl),
network_id: 42,
},
},
compilers: {
solc: {
version: "0.8.4",
optimizer: { enabled: true, runs: 200 }
},
},
};
var MyContract = artifacts.require("MyContract");
module.exports = deployer => {
deployer.then(async () => {
await deployer.deploy(MyContract, param1, param2);
const myContract = await MyContract.deployed();
await myContract.changeOwnership(multiSigAddress);
});
};Check out the migrations link here for the full documentation on how to use them.
Downsides of using Truffle for mainnet
It's worth mentioning that Truffle itself is far from optimal to deploy to mainnet for several reasons:
- A special migrations contract being deployed increases gas costs. And even though highly requested, it's still not possible to easily remove it.
- Long migrations in Truffle are very, very painful on mainnet.
- Gas prices make mainnet deployments very hard. You can set a gas price in the Truffle config, but this will be one gas price for the whole period of your migrations. So if gas prices are increasing a lot during your deployment, good luck getting them included into a block by miners. If a transaction is not mined in a few minutes, Truffle will just stop your deployment. Your only option is to set a very high gas price and hope everything deploys quickly.
- Your internet connection might cause problems. You better not loose your connection during long deployments or otherwise prepare to start from the beginning again.
At the least Truffle now does dry run simulations before the actual deployments. You can skip those on testnets using --skip-dry-run, but don't do this for mainnet. It will ensure you at least don't get any transaction reverts in the middle having to restart from the beginning.
All in all if you have the money to pay for the increased costs using Truffle go ahead and use it. Otherwise read on for alternatives.
b. Remix
Remix is my favorite tool for quick mainnet deployments. You have full control over what's happening, because you will do each step manually using MetaMask.
Once you have a compiled contract, deploying is as easy as typing the input parameters and clicking deploy. You can get deployable contracts for Remix from Truffle using truffle-flattener or for Hardhat using the built-in flatten command. Since you are using MetaMask, you will
- be automatically connected to Infura
- have the ability to deploy with hardware wallets
- be able to choose an exact gas price for each transaction
- be able to speed up or cancel pending transactions
Downsides of using Remix
It's not all roses and unicorns however. With Remix you have to do every step manually. That means entering every parameter manually. Deploying every contract manually. Calling every function manually. You can see how painful this would be for very long deployment procedures.
c. Hardhat
There's no direct support for deployments in Hardhat. However you can write a script that deploys a contract via ethers.js and call it from the hardhat command. An example on how to do this can be seen in the solidity-template.
You can see the example deploy script on the right. The script can be invoked using:
$ npx hardhat run scripts/deploy.tsAlternatively, you can use the hardhat-deploy plugin which most interestingly adds capability to store finished deployments in files.
import { Contract, ContractFactory } from "ethers";
import { ethers } from "hardhat";
async function main(): Promise<void> {
const Greeter: ContractFactory
= await ethers.getContractFactory("Greeter");
const greeter: Contract
= await Greeter.deploy("Hello, Buidler!");
await greeter.deployed();
console.log("Greeter deployed to: ", greeter.address);
}
main()
.then(() => process.exit(0))
.catch((error: Error) => {
console.error(error);
process.exit(1);
});d. Web3
Of course you can always build your custom deployment logic directly using Web3 (or ethers.js). This is very useful when you are deploying contracts frequently and require custom logic for storing the deployment information. Web3 directly supports deployments using myContract.deploy().
const myContract = new web3.eth.Contract(jsonABI)
myContract.deploy({
data: '0x12345...', // bytecode
arguments: [123, 'My String'] // constructor arguments
}).send({
from: '0x1234567890123456789012345678901234567891',
gas: 1500000,
gasPrice: '30000000000000'
}e. Truffle Teams (Premium)
Remember the issues with deploying to mainnet with Truffle from above? Well there's a solution for them called Truffle Teams. It's free for open-source projects, but otherwise will cost a few dollars per month. But with it you get a project dashboard. This comes with a direct connection to Github and is running your tests as continuous integration. Any successful builds can then be deployed from the dashboard.
This allows you to connect MetaMask for your deployments, meaning full control of gas prices and speeding them up.
See the full documentation for the Truffle Teams deployments here.
4. Considerations post deployment
Right after the deployment to mainnet, you should verify the contract source code on Etherscan and Sourcify. This involves submitting the Solidity code to the service which will compile it and verify that it matches the deployed bytecode. After a successful verification users get more information in Etherscan, can directly interact with it on Etherscan or fetch the code from Sourcify from supporting tools like Remix.
You can verify your contracts manually on the Etherscan website. Alternatively there are plugins for automatic verification using Truffle, Hardhat and a direct Etherscan API.
For how to use Sourcify, check out my previous blog post here.
Solidity Developer
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The big picture of Solidity and Blockchain development in 2020
Overview of the most important technologies, services and tools that you need to know
Now, I do not know about you, but I remember when I first started with Solidity development being very confused by all the tools and services and how they work in connection with one another. If you are like me, this overview will help you understand the big picture of Solidity development. As I...
Design Pattern Solidity: Free up unused storage
Why you should clean up after yourself
You may or may not be used to a garbage collectors in your previous programming language. There is no such thing in Solidity and even if there was a similar concept, you would still be better off managing state data yourself. Only you as a programmer can know exactly which data will not be used...
How to setup Solidity Developer Environment on Windows
What you need to know about developing on Windows
Using Windows for development, especially for Solidity development, can be a pain sometimes, but it does not have to be. Once you have configured your environment properly, it can actually be extremely efficient and Windows is a very, very stable OS, so your overall experience can be amazing. The...
Avoiding out of gas for Truffle tests
How you do not have to worry about gas in tests anymore
You have probably seen this error message a lot of times: Error: VM Exception while processing transaction: out of gas Disclaimer : Unfortunately, this does not always actually mean what it is saying when using Truffle , especially for older versions. It can occur for various reasons and might be...
Design Pattern Solidity: Stages
How you can design stages in your contract
Closely related to the concept of finite-state machines, this pattern will help you restrict functions in your contract. You will find a lot of situations where it might be useful. Any time a contract should allow function calls only in certain stages. Let's look at an example: contract Pool {...
Web3 1.2.5: Revert reason strings
How to use the new feature
A new Web3 version was just released and it comes with a new feature that should make your life easier. With the latest version 1.2.5, you can now see the the revert reason if you use the new handleRevert option. You can activate it easily by using web3.eth.handleRevert = true . Now when you use...
Gaining back control of the internet
How Ocelot is decentralizing cloud computing
I recently came across an ambitious company that will completely redefine the way we are using the internet. Or rather, the way we are using its underlying infrastructure which ultimately is the internet. While looking at their offering, I also learned how to get anonymous cloud machines, you...
Devcon 5 - Review
Impressions from the conference
I had a lot to catch up on after Devcon. Also things didn't go quite as planned, so please excuse my delayed review! This year's Devcon was certainly stormy with a big typhoon warning already on day 1. Luckily (for us, not the people in Tokyo), it went right past Osaka. Nevertheless, a lot of...
Devcon 5 - Information, Events, Links, Telegram
What you need to know
Devcon 5 is coming up soon and there are already lots of events available, information about Osaka and more. Here is a short overview: Events Events Calendar Events Google Docs Events Kickback Most events are in all three, but if you really want to see all, you will have to look at all three...
Design Pattern Solidity: Off-chain beats on-chain
Why you should do as much as possible off-chain
As you might have realized, Ethereum transactions are anything but cheap. In particular, if you are computing complex things or storing a lot of data. That means sometimes we cannot put all logic inside Solidity. Instead, we can utilize off-chain computations to help us. A very simple example...
Design Pattern Solidity: Initialize Contract after Deployment
How to use the Initializable pattern
There are a few reasons why you might want to initialize a contract after deployment and not directly by passing constructor arguments. But first let's look at an example: contract MyCrowdsale { uint256 rate; function initialize(uint256 _rate) public { rate = _rate; } } What's the advantage over...
Consensys Blockchain Jobs Report
What the current blockchain job market looks like
Consensys published their blockchain jobs report which you can checkout in their Blockchain Developer Job Kit. The most interesting aspects are Blockchain developer jobs have been growing at a rate of 33x of the previous year according to LinkedIns jobs report Typical salary is about...
Provable — Randomness Oracle
How the Oraclize random number generator works
One particularly interesting approach by Provable is the usage of a hardware security device, namely the Ledger Nano S. It uses a trusted execution environment to generate random numbers and provides a Provable Connector Contract as interface. How to use the Provable Randomness Oracle? Use the...
Solidity Design Patterns: Multiply before Dividing
Why the correct order matters!
There has been a lot of progress since the beginning of Ethereum about best practices in Solidity. Unfortunately, I have the feeling that most of the knowledge is within the circle of experienced people and there aren’t that many online resources about it. That is why I would like to start this...
Devcon 5 Applications closing in one week
Devcon 5 Applications closing
Watch out for the Devcon 5 applications. You only have one week left to apply either as Buidler Student Scholarship Press Devcon is by far the biggest and most impressive Ethereum conference in the world. And it's full of developers! I am especially excited about the cool location this year in...
Randomness and the Blockchain
How to achieve secure randomness for Solidity smart contracts?
When we talk about randomness and blockchain, these are really two problems: 1. How to generate randomness in smart contracts? 2. How to produce randomness for proof-of-stake (POS) systems? Or more generally, how to produce trusted randomness in public distributed systems? There is some overlap...