Optimism Documentation

The consensus client (also called the rollup node) builds, relays, and verifies the canonical chain of blocks. This guide covers configuration for the most popular consensus client implementations.

Always run your consensus client and execution client in a one-to-one configuration. Don’t run multiple execution client instances behind one consensus client, or vice versa.

Consensus clients

Choose the consensus client that best fits your needs:

op-node
kona-node

op-node configuration

op-node is the reference implementation of the OP Stack consensus client, written in Go.

Minimal configuration

The minimum required flags for running op-node:

op-node \
  --l1=https://ethereum-rpc-endpoint.example.com \
  --l1.beacon=https://ethereum-beacon-endpoint.example.com \
  --l2=http://localhost:8551 \
  --l2.jwt-secret=/path/to/jwt-secret.txt \
  --network=op-mainnet \
  --rpc.addr=0.0.0.0 \
  --rpc.port=9545

Sequencer configuration

If you’re running a sequencer node, use these additional flags:

--rpc.enable-admin \
--sequencer.enabled \
--sequencer.l1-confs=4 \
--p2p.sequencer.key=<your-sequencer-private-key>

Keep your sequencer private key secure and never commit it to version control. Use environment variables or secure key management systems in production.

l2.enginekind

Controls op-node’s engine-API behavior to match the connected execution client. Supported values:

reth — default; for op-reth.
geth — for op-geth (deprecated, see the op-geth deprecation notice).

The default is reth, so op-reth operators do not need to set this flag. Set --l2.enginekind=geth only if you are running op-geth.

Complete reference

For all available configuration options, see the op-node configuration reference.

kona-node configuration

kona-node is an experimental Rust-based implementation of the OP Stack consensus client.

kona-node is experimental and may not be production-ready. Use with caution.

Basic configuration

kona-node follows a similar configuration pattern to op-node:

kona-node \
  --l1-rpc-url=https://ethereum-rpc-endpoint.example.com \
  --l2-rpc-url=http://localhost:8551 \
  --jwt-secret=/path/to/jwt-secret.txt \
  --network=op-mainnet

Additional resources

For more details on kona-node configuration, see:

JWT secret

To communicate with execution client and enable the Engine API, you’ll also need to generate a JWT secret file and enable the consensus client’s authenticated RPC endpoint. To generate the JWT secret file:

openssl rand -hex 32 > jwt-secret.txt

Run a node

Guides

Tutorials

Clients

Reference

Consensus client configuration

Consensus clients

op-node configuration

Minimal configuration

Sequencer configuration

l2.enginekind

Complete reference

kona-node configuration

Basic configuration

Additional resources

JWT secret

​Consensus clients

​op-node configuration

​Minimal configuration

​Sequencer configuration

​l2.enginekind

​Complete reference

​kona-node configuration

​Basic configuration

​Additional resources

​JWT secret

Consensus clients

op-node configuration

Minimal configuration

Sequencer configuration

l2.enginekind

Complete reference

kona-node configuration

Basic configuration

Additional resources

JWT secret