Setup Production zkNode

Polygon zkEVM is now available on the Mainnet Beta for developers to launch smart contracts, execute transactions, and experiment with the network. This tutorial extends the exploration by allowing developers to launch their own node on the zkEVM Public Testnet.

Before we begin, this document is fairly technical and requires prior exposure to Docker and CLI. Post spinning up your zkNode instance, you will be able to run the Synchronizer and utilize the JSON-RPC interface.

info

Sequencer and Prover functionalities are not covered in this document as they are still undergoing development and rigorous testing.

Syncing zkNode currently takes anywhere between 1-2 days depending on various factors. The team is working on snapshots to improve the syncing time.

Prerequisites

This tutorial assumes that you have docker-compose already installed. If you need any help with the installation, please check the official docker-compose installation guide.

It is highly recommended that you create a separate folder for installing and working around the zkNode. We won't be cloning any repository (unlike local zkNode setup) so it's better to create a folder before starting the zkNode setup: mkdir -p /$HOME/zkevm-node.

Minimum System Requirements

caution

zkProver does not work on ARM-based Macs yet, and using WSL/WSL2 on Windows is not advisable. Currently, zkProver optimizations require CPUs that support the AVX2 instruction, which means some non-M1 computers, such as AMD, won't work with the software regardless of the OS.

• 16GB RAM
• 4-core CPU
• 20GB Storage (This will increase over time)

About Batch Rate

Batches are closed every 10s, or whenever they are full (which can happen when there are high network loads). Also, how frequent batches are closed is subject to change as it depends on the prevailing configurations. The batch rate will always need to be updated accordingly.

Network Components

Here is a list of crucial network components that are required before you can run the zkNode:

• Ethereum Node - Use geth or any service providing a JSON RPC interface for accessing the L1 network
• zkEVM-Node (or zkNode) - L2 Network
  • Synchronizer - Responsible for synchronizing data between L1 and L2
  • JSON RPC Server - Interface to L2 network

Let's set up each of the above components!

Ethereum Node Setup

The Ethereum Node will be the first component we will set up. It is the first because synchronizing the Ethereum network will take a long time, so we will keep it synchronized while we set up the other components to take advantage of this required time.

There are numerous ways to set up an Ethereum L1 environment; we will use Geth for this. We recommend Geth, but any Goerli node should do. Follow the instructions provided in this guide to setup and install Geth.

If you plan to have more than one zkNode in your infrastructure, we advise using a machine that is specifically dedicated to this component.

zkNode Setup

Once the L1 installation is complete, we can start the zkNode setup. This is the most straightforward way to run a zkEVM node and it's fine for most use cases. However, if you want to provide service to a large number of users, you should modify the default configuration.

Furthermore, this method is purely subjective and feel free to run this software in a different manner. For example, Docker is not required, you could simply use the Go binaries directly.

Let's start setting up our zkNode:

1. Launch your command line/terminal and set the variables using below commands:

   # define the network("mainnet" or "testnet")
   ZKEVM_NET=testnet
   
   # define installation path
   ZKEVM_DIR=./path_to_install
   
   # define your config directory
   ZKEVM_CONFIG_DIR=./path_to_config

2. Download and extract the artifacts. Note that you may need to install unzip before running this command.

   curl -L https://github.com/0xPolygonHermez/zkevm-node/releases/latest/download/$ZKEVM_NET.zip > $ZKEVM_NET.zip && unzip -o $ZKEVM_NET.zip -d $ZKEVM_DIR && rm $ZKEVM_NET.zip

3. Copy the example.env file with the environment parameters: cp $ZKEVM_DIR/$ZKEVM_NET/example.env $ZKEVM_CONFIG_DIR/.env

4. The example.env file must be modified according to your configurations. Edit the .env file with your favourite editor (we'll use nano in this guide): nano $ZKEVM_CONFIG_DIR/.env

   # URL of a JSON RPC for Goerli
   ZKEVM_NODE_ETHERMAN_URL = "http://your.L1node.url"
   
   # PATH WHERE THE STATEDB POSTGRES CONTAINER WILL STORE PERSISTENT DATA
   ZKEVM_NODE_STATEDB_DATA_DIR = "/path/to/persistent/data/stetedb"
   
   # PATH WHERE THE POOLDB POSTGRES CONTAINER WILL STORE PERSISTENT DATA
   ZKEVM_NODE_POOLDB_DATA_DIR = "/path/to/persistent/data/pooldb"

5. To run the zkNode instance, run the following command:

   sudo docker compose --env-file $ZKEVM_CONFIG_DIR/.env -f $ZKEVM_DIR/$ZKEVM_NET/docker-compose.yml up -d

6. Run this command to check if everything went well and all the components are running properly:

   docker compose --env-file $ZKEVM_CONFIG_DIR/.env -f $ZKEVM_DIR/$ZKEVM_NET/docker-compose.yml ps

   You will see a list of the following containers:

   • zkevm-rpc
   • zkevm-sync
   • zkevm-state-db
   • zkevm-pool-db
   • zkevm-prover

7. You should now be able to run queries to the JSON-RPC endpoint at http://localhost:8545.

Testing

Run the following query to get the most recently synchronized L2 block; if you call it every few seconds, you should see the number grow:

curl -H "Content-Type: application/json" -X POST --data '{"jsonrpc":"2.0","method":"eth_blockNumber","params":[],"id":83}' http://localhost:8545

Stopping the zkNode

Use the below command to stop the zkNode instance:

sudo docker compose --env-file $ZKEVM_CONFIG_DIR/.env -f $ZKEVM_DIR/$ZKEVM_NET/docker-compose.yml down

Updating the zkNode

To update the zkNode software, repeat the setup steps, being careful not to overwrite the configuration files that you have modified.

In other words, instead of running cp $ZKEVM_DIR/testnet/example.env $ZKEVM_CONFIG_DIR/.env, check if the variables of $ZKEVM_DIR/testnet/example.env have been renamed or there are new ones, and update $ZKEVM_CONFIG_DIR/.env accordingly.

Troubleshooting

• It's possible that the machine you're using already uses some of the necessary ports. In this case you can change them directly in $ZKEVM_DIR/testnet/docker-compose.yml.

• If one or more containers are crashing, please check the logs using the below command:

  docker compose --env-file $ZKEVM_CONFIG_DIR/.env -f $ZKEVM_DIR/$ZKEVM_NET/docker-compose.yml logs <cointainer_name>