How to set up a local Ethereum testnet
Introduction
This guide walks you through the process of instantiating a configurable local Ethereum testnet, deploying a smart contract to it, and using the testnet to run tests against your dApp. This guide is designed for dApp developers who want to develop and test their dApps locally against different network configurations before deploying to a live testnet or the mainnet.
In this guide, you will:
- Instantiate a local Ethereum testnet with the
ethereum-packageusing Kurtosis, - Connect your Hardhat dApp development environment to the local testnet to compile, deploy, and test a dApp, and
- Configure the local testnet, including parameters like number of nodes and specific EL/CL client pairings, to enable development and testing workflows against various network configurations.
What is Kurtosis?
Kurtosis is a composable build system designed for configuring multi-container environments. It specifically enables developers to create reproducible environments that require dynamic setup logic, such as blockchain testnets.
In this guide, the Kurtosis ethereum-package spins up a local Ethereum testnet with support for the geth Execution Layer (EL) client, as well as teku, lighthouse, and lodestar Consensus Layer (CL) clients. This package serves as a configurable and composable alternative to networks in frameworks like Hardhat Network, Ganache, and Anvil. Kurtosis offers developers greater control and flexibility over the testnets they use, which is a major reason why the Ethereum Foundation used Kurtosis to test the Merge and continues to use it for testing network upgrades.
Setting up Kurtosis
Before you proceed, make sure you have:
- Installed and started the Docker engine on your local machine
- Installed the Kurtosis CLI (or upgraded it to the latest release, if you already have the CLI installed)
- Installed Node.js, yarn, and npx (for your dApp environment)
Instantiating a local Ethereum testnet
To spin up a local Ethereum testnet, run:
kurtosis --enclave local-eth-testnet run github.com/kurtosis-tech/ethereum-package
This command names your network: "local-eth-testnet” using the --enclave flag.
Kurtosis will print the steps its taking under the hood as it works to interpret, validate, and then execute the instructions. At the end, you should see an output that resembles the following:
INFO[2023-04-04T18:09:44-04:00] ======================================================
INFO[2023-04-04T18:09:44-04:00] || Created enclave: local-eth-testnet ||
INFO[2023-04-04T18:09:44-04:00] ======================================================
Name: local-eth-testnet
UUID: 39372d756ae8
Status: RUNNING
Creation Time: Tue, 04 Apr 2023 18:09:03 EDT
========================================= Files Artifacts =========================================
UUID Name
d4085a064230 cl-genesis-data
1c62cb792e4c el-genesis-data
bd60489b73a7 genesis-generation-config-cl
b2e593fe5228 genesis-generation-config-el
d552a54acf78 geth-prefunded-keys
5f7e661eb838 prysm-password
054e7338bb59 validator-keystore-0
========================================== User Services ==========================================
UUID Name Ports Status
e20f129ee0c5 cl-client-0-beacon http: 4000/tcp -> <http://127.0.0.1:54261> RUNNING
metrics: 5054/tcp -> <http://127.0.0.1:54262>
tcp-discovery: 9000/tcp -> 127.0.0.1:54263
udp-discovery: 9000/udp -> 127.0.0.1:60470
a8b6c926cdb4 cl-client-0-validator http: 5042/tcp -> 127.0.0.1:54267 RUNNING
metrics: 5064/tcp -> <http://127.0.0.1:54268>
d7b802f623e8 el-client-0 engine-rpc: 8551/tcp -> 127.0.0.1:54253 RUNNING
rpc: 8545/tcp -> 127.0.0.1:54251
tcp-discovery: 30303/tcp -> 127.0.0.1:54254
udp-discovery: 30303/udp -> 127.0.0.1:53834
ws: 8546/tcp -> 127.0.0.1:54252
514a829c0a84 prelaunch-data-generator-1680646157905431468 <none> STOPPED
62bd62d0aa7a prelaunch-data-generator-1680646157915424301 <none> STOPPED
05e9619e0e90 prelaunch-data-generator-1680646157922872635 <none> STOPPED
Congratulations! You used Kurtosis to instantiate a local Ethereum testnet, with a CL (lighthouse) and EL client (geth), over Docker.
Review
In this section, you executed a command that directed Kurtosis to use the ethereum-package hosted remotely on GitHub to spin up a local Ethereum testnet within a Kurtosis Enclave. Inside your enclave, you will find both "file artifacts" and "user services".
The File Artifacts in your enclave include all the data generated and utilized to bootstrap the EL and CL clients. The data was created using the prelaunch-data-generator service built from this Docker image
User services display all the containerized services operating in your enclave. You will notice that a single node, featuring both an EL client and a CL client, has been created.
Connect your dApp development environment to the local Ethereum testnet
Setup the dApp development environment
Now that you have a running local testnet, you can connect your dApp development environment to use your local testnet. The Hardhat framework will be used in this guide to deploy a blackjack dApp to your local testnet.
To set up your dApp development environment, clone the repository that contains our sample dApp and install its dependencies, run:
git clone https://github.com/kurtosis-tech/awesome-kurtosis.git && cd awesome-kurtosis/smart-contract-example && yarn
The smart-contract-example folder used here contains the typical setup for a dApp developer using the Hardhat framework:
contracts/contains a few simple smart contracts for a Blackjack dAppscripts/contains a script to deploy a token contract to your local Ethereum networktest/contains a simple .js test for your token contract to confirm each player in our Blackjack dApp has 1000 minted for themhardhat.config.tsconfigures your Hardhat setup
Configure Hardhat to use the local testnet
With your dApp development environment set up, you will now connect Hardhat to use the local Ethereum testnet generated using Kurtosis. To accomplish this, replace <$YOUR_PORT> in the localnet struct in your hardhat.config.ts config file with the port of the rpc uri output from any el-client-<num> service. In this sample case, the port would be 64248. Your port will be different.
Example in hardhat.config.ts:
localnet: {
url: 'http://127.0.0.1:<$YOUR_PORT>',// TODO: REPLACE $YOUR_PORT WITH THE PORT OF A NODE URI PRODUCED BY THE ETH NETWORK KURTOSIS PACKAGE
// These are private keys associated with prefunded test accounts created by the ethereum-package
// <https://github.com/kurtosis-tech/ethereum-package/blob/main/src/prelaunch_data_generator/genesis_constants/genesis_constants.star>
accounts: [
"ef5177cd0b6b21c87db5a0bf35d4084a8a57a9d6a064f86d51ac85f2b873a4e2",
"48fcc39ae27a0e8bf0274021ae6ebd8fe4a0e12623d61464c498900b28feb567",
"7988b3a148716ff800414935b305436493e1f25237a2a03e5eebc343735e2f31",
"b3c409b6b0b3aa5e65ab2dc1930534608239a478106acf6f3d9178e9f9b00b35",
"df9bb6de5d3dc59595bcaa676397d837ff49441d211878c024eabda2cd067c9f",
"7da08f856b5956d40a72968f93396f6acff17193f013e8053f6fbb6c08c194d6",
],
},
Once you save your file, your Hardhat dApp development environment is now connected to your local Ethereum testnet! You can verify that your testnet is working by running:
npx hardhat balances --network localnet
The output should look something like this:
0x878705ba3f8Bc32FCf7F4CAa1A35E72AF65CF766 has balance 10000000000000000000000000
0x4E9A3d9D1cd2A2b2371b8b3F489aE72259886f1A has balance 10000000000000000000000000
0xdF8466f277964Bb7a0FFD819403302C34DCD530A has balance 10000000000000000000000000
0x5c613e39Fc0Ad91AfDA24587e6f52192d75FBA50 has balance 10000000000000000000000000
0x375ae6107f8cC4cF34842B71C6F746a362Ad8EAc has balance 10000000000000000000000000
0x1F6298457C5d76270325B724Da5d1953923a6B88 has balance 10000000000000000000000000
This confirms that Hardhat is using your local testnet and detects the pre-funded accounts created by the ethereum-package.
Deploy and test your dApp locally
With the dApp development environment fully connected to the local Ethereum testnet, you can now run development and testing workflows against your dApp using the local testnet.
To compile and deploy the ChipToken.sol smart contract for local prototyping and development, run:
npx hardhat compile
npx hardhat run scripts/deploy.ts --network localnet
The output should look something like:
ChipToken deployed to: 0xAb2A01BC351770D09611Ac80f1DE076D56E0487d
Now try running the simple.js test against your local dApp to confirm each player in our Blackjack dApp has 1000 minted for them:
The output should look something like this:
npx hardhat test --network localnet
The output should look something like this:
ChipToken
mint
✔ should mint 1000 chips for PLAYER ONE
1 passing (654ms)
Review
At this point, you’ve now set up a dApp development environment, connected it to a local Ethereum network created by Kurtosis, and have compiled, deployed, and ran a simple test against your dApp.
Now let’s explore how you can configure the underlying network for testing our dApps under varying network configurations.
Configuring the local Ethereum testnet
Changing the client configurations and number of nodes
Your local Ethereum testnet can be configured to use different EL and CL client pairs, as well as a varying number of nodes, depending on the scenario and specific network configuration you want to develop or test. This means that, once set up, you can spin up a customized local testnet and use it to run the same workflows (deployment, tests, etc.) under various network configurations to ensure everything works as expected. To learn more about the other parameters you can modify, visit this link.
Give it a try! You can pass various configuration options to the ethereum-package via a YAML/JSON file. This network params YAML/JSON file provides the specific configurations that Kurtosis will use to set up the local Ethereum network.
Take the default configuration file and edit it to spin up two nodes with different EL/CL pairs:
- Node 1 with
geth/lighthouse - Node 2 with
geth/lodestar - Node 3 with
geth/teku
This configuration creates a heterogeneous network of Ethereum node implementations for testing your dApp. Your configuration file should now look like:
{
"participants":[{
"el_client_type": "geth",
"el_client_image": "",
"el_client_log_level": "",
"cl_client_type": "lighthouse",
"cl_client_image": "",
"cl_client_log_level": "",
"beacon_extra_params": [],
"el_extra_params": [],
"validator_extra_params": [],
"builder_network_params": null
},
{
"el_client_type": "geth",
"el_client_image": "",
"el_client_log_level": "",
"cl_client_type": "lodestar",
"cl_client_image": "",
"cl_client_log_level": "",
"beacon_extra_params": [],
"el_extra_params": [],
"validator_extra_params": [],
"builder_network_params": null
},
{
"el_client_type": "geth",
"el_client_image": "",
"el_client_log_level": "",
"cl_client_type": "teku",
"cl_client_image": "",
"cl_client_log_level": "",
"beacon_extra_params": [],
"el_extra_params": [],
"validator_extra_params": [],
"builder_network_params": null
}],
"network_params":{
"preregistered_validator_keys_mnemonic": "giant issue aisle success illegal bike spike question tent bar rely arctic volcano long crawl hungry vocal artwork sniff fantasy very lucky have athlete",
"num_validator_keys_per_node": 64,
"network_id": "3151908",
"deposit_contract_address": "0x4242424242424242424242424242424242424242",
"seconds_per_slot": 12,
"genesis_delay": 120,
"capella_fork_epoch": 5
}
}
Each participants struct maps to a node in the network, so 3 participants structs will tell Kurtosis to spin up 3 nodes in your network. Each participants struct will allow you to specify the EL and CL pair used for that specific node.
The network_params struct configures the network settings that are used to create the genesis files for each node as well as other settings like the seconds per slot of the network.
Save your edited params file in any directory you wish (in the example below, it is saved to the desktop) and then use it to run your Kurtosis package by running:
kurtosis clean -a && kurtosis run --enclave local-eth-testnet github.com/kurtosis-tech/ethereum-package --args-file ~/eth-network-params.yaml
:::TIP
Note that the kurtosis clean -a command is used here to instruct Kurtosis to destroy the old testnet and its contents before starting a new one up.
:::
Again, Kurtosis will work for a bit and print out the individual steps that are taking place. Eventually, the output should look something like:
Starlark code successfully run. No output was returned.
INFO[2023-04-07T11:43:16-04:00] ==========================================================
INFO[2023-04-07T11:43:16-04:00] || Created enclave: local-eth-testnet ||
INFO[2023-04-07T11:43:16-04:00] ==========================================================
Name: local-eth-testnet
UUID: bef8c192008e
Status: RUNNING
Creation Time: Fri, 07 Apr 2023 11:41:58 EDT
========================================= Files Artifacts =========================================
UUID Name
cc495a8e364a cl-genesis-data
7033fcdb5471 el-genesis-data
a3aef43fc738 genesis-generation-config-cl
8e968005fc9d genesis-generation-config-el
3182cca9d3cd geth-prefunded-keys
8421166e234f prysm-password
d9e6e8d44d99 validator-keystore-0
23f5ba517394 validator-keystore-1
4d28dea40b5c validator-keystore-2
========================================== User Services ==========================================
UUID Name Ports Status
485e6fde55ae cl-client-0-beacon http: 4000/tcp -> http://127.0.0.1:65010 RUNNING
metrics: 5054/tcp -> http://127.0.0.1:65011
tcp-discovery: 9000/tcp -> 127.0.0.1:65012
udp-discovery: 9000/udp -> 127.0.0.1:54455
73739bd158b2 cl-client-0-validator http: 5042/tcp -> 127.0.0.1:65016 RUNNING
metrics: 5064/tcp -> http://127.0.0.1:65017
1b0a233cd011 cl-client-1-beacon http: 4000/tcp -> 127.0.0.1:65021 RUNNING
metrics: 8008/tcp -> 127.0.0.1:65023
tcp-discovery: 9000/tcp -> 127.0.0.1:65024
udp-discovery: 9000/udp -> 127.0.0.1:56031
validator-metrics: 5064/tcp -> 127.0.0.1:65022
949b8220cd53 cl-client-1-validator http: 4000/tcp -> 127.0.0.1:65028 RUNNING
metrics: 8008/tcp -> 127.0.0.1:65030
tcp-discovery: 9000/tcp -> 127.0.0.1:65031
udp-discovery: 9000/udp -> 127.0.0.1:60784
validator-metrics: 5064/tcp -> 127.0.0.1:65029
c34417bea5fa cl-client-2 http: 4000/tcp -> 127.0.0.1:65037 RUNNING
metrics: 8008/tcp -> 127.0.0.1:65035
tcp-discovery: 9000/tcp -> 127.0.0.1:65036
udp-discovery: 9000/udp -> 127.0.0.1:63581
e19738e6329d el-client-0 engine-rpc: 8551/tcp -> 127.0.0.1:64986 RUNNING
rpc: 8545/tcp -> 127.0.0.1:64988
tcp-discovery: 30303/tcp -> 127.0.0.1:64987
udp-discovery: 30303/udp -> 127.0.0.1:55706
ws: 8546/tcp -> 127.0.0.1:64989
e904687449d9 el-client-1 engine-rpc: 8551/tcp -> 127.0.0.1:64993 RUNNING
rpc: 8545/tcp -> 127.0.0.1:64995
tcp-discovery: 30303/tcp -> 127.0.0.1:64994
udp-discovery: 30303/udp -> 127.0.0.1:58096
ws: 8546/tcp -> 127.0.0.1:64996
ad6f401126fa el-client-2 engine-rpc: 8551/tcp -> 127.0.0.1:65003 RUNNING
rpc: 8545/tcp -> 127.0.0.1:65001
tcp-discovery: 30303/tcp -> 127.0.0.1:65000
udp-discovery: 30303/udp -> 127.0.0.1:57269
ws: 8546/tcp -> 127.0.0.1:65002
12d04a9dbb69 prelaunch-data-generator-1680882122181135513 <none> STOPPED
5b45f9c0504b prelaunch-data-generator-1680882122192182847 <none> STOPPED
3d4aaa75e218 prelaunch-data-generator-1680882122201668972 <none> STOPPED
Congratulations! You’ve successfully configured your local testnet to have 3 nodes instead of 1. To run the same workflows you did before against your dApp (deploy & test), perform the same operations we did before by replacing the <$YOUR_PORT> in the localnet struct in your hardhat.config.ts config file with the port of the rpc uri output from any el-client-<num> service in your new, 3-node local testnet.
Conclusion
And that's it! To recap this short guide, you:
- Created a local Ethereum testnet over Docker using Kurtosis
- Connected your local dApp development environment to the local Ethereum network
- Deployed a dApp and ran a simple test against it on the local Ethereum network
- Configured the underlying Ethereum network to have 3 nodes
We’d love to hear from you on what went well for you, what could be improved, or to answer any of your questions. Don’t hesitate to reach out via a post in our discussions forum on Github or in our Discord Server.
Other examples and guides
We encourage you to check out our quickstart (where you’ll build a Postgres database and API on top) and our other examples in our awesome-kurtosis repository where you’ll find some great examples.