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Overview

After deploying the L1 system contracts for your OP Stack chain, you need to generate two files to run nodes on the L2 network:
  • Genesis file (genesis.json): Initializes the execution client (op-geth)
  • Rollup configuration file (rollup.json): Configures the consensus client (op-node)
This guide shows you how to generate these files from your L1 contract deployment data using op-deployer.

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Prerequisites

Before generating genesis and rollup configuration files, ensure you have:
  1. Deployed the L1 contracts successfully using the op-deployer apply command
  2. Access to your deployment workspace directory (.deployer if you’ve followed the instructions in the L1 deployment contracts guide)

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Generating genesis and rollup files

After your L1 contracts have been deployed, follow these steps to generate the configuration files:

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Step 1: Locate your deployment state file

The op-deployer tool creates a state.json file in your workspace directory that contains all the necessary information about your deployed contracts. Verify that this file exists in your workspace: 
ls -la .deployer/state.json

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Step 2: Generate the L2 genesis file

Use the inspect genesis command to retrieve your L2 genesis file: 
op-deployer inspect genesis --workdir .deployer <L2_CHAIN_ID> > .deployer/genesis.json
Replace <L2_CHAIN_ID> with your L2 network’s chain ID.

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Step 3: Generate the rollup configuration file

Use the inspect rollup command to retrieve your rollup configuration file: 
op-deployer inspect rollup --workdir .deployer <L2_CHAIN_ID> > .deployer/rollup.json

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Step 4: Verify the generated files

Examine the generated files to ensure they contain the expected configuration: 
# View the genesis file structure
jq . .deployer/genesis.json | head -20

# View the rollup configuration
jq . .deployer/rollup.json
The genesis.json file contains the initial state of your L2 blockchain, including:
  • Chain configuration parameters
  • Initial account states
  • Genesis block properties
The rollup.json file contains the rollup protocol parameters, including:
  • L1 contract addresses
  • Sequencing settings
  • Protocol upgrade activation times

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Troubleshooting

If you encounter issues with the generated files:
  • Verify that your L1 contract deployment was successful
  • Check that you’re using the correct L2 chain ID in the generation commands
  • Ensure your state.json file is up-to-date with your latest deployment
Never manually edit the generated genesis or rollup files unless you fully understand the implications. Incorrect configurations can lead to consensus failures or chain security issues.

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Next steps

  • Learn how to initialize op-geth with your genesis.json file
  • Learn how to configure op-node with your rollup.json file
  • Learn more about the off-chain architecture