Optimism Documentation

This guide shows how to run kona-node in sequencer mode from the command line. For how sequencer mode works internally and how to configure it programmatically through the Node SDK, see the sequencer mode design page.

Sequencer mode is an advanced configuration primarily used by rollup operators. Most users will run nodes in the default validator mode.

Basic Sequencer Setup

To run a Kona node in sequencer mode:

kona-node node \
  --mode=Sequencer \
  --l1-eth-rpc=http://l1-node:8545 \
  --l1-beacon=http://l1-beacon:5052 \
  --l2-engine-rpc=http://l2-execution:8551 \
  --l2.jwt-secret=./jwt.hex \
  --chain=123456

Required Arguments

Required ConfigurationSequencer mode requires all standard node arguments plus the --mode=Sequencer flag. Missing any required argument will prevent the node from starting.

Argument	Flag	Environment Variable	Description
Mode	`--mode`	`KONA_NODE_MODE`	Must be set to `Sequencer`
L1 RPC	`--l1-eth-rpc`	`KONA_NODE_L1_ETH_RPC`	L1 execution client RPC URL
L1 Beacon	`--l1-beacon`	`KONA_NODE_L1_BEACON`	L1 beacon API URL
L2 Engine	`--l2-engine-rpc`	`KONA_NODE_L2_ENGINE_RPC`	L2 engine API endpoint
JWT Secret	`--l2.jwt-secret`	`KONA_NODE_L2_ENGINE_AUTH`	Path to JWT secret file
Chain ID	`--chain`	`KONA_NODE_L2_CHAIN_ID`	L2 chain identifier

Sequencer-Specific Flags

Flag	Environment Variable	Default	Description
`--sequencer.stopped`	`KONA_NODE_SEQUENCER_STOPPED`	`false`	Start sequencer in stopped state
`--sequencer.max-safe-lag`	`KONA_NODE_SEQUENCER_MAX_SAFE_LAG`	`0`	Max L2 blocks between safe and unsafe heads
`--sequencer.l1-confs`	`KONA_NODE_SEQUENCER_L1_CONFS`	`4`	L1 confirmations for origin selection
`--sequencer.recover`	`KONA_NODE_SEQUENCER_RECOVER`	`false`	Force recovery mode operation
`--conductor.rpc`	`KONA_NODE_CONDUCTOR_RPC`	-	Conductor service RPC endpoint
`--conductor.rpc.timeout`	`KONA_NODE_CONDUCTOR_RPC_TIMEOUT`	`1`	Conductor RPC timeout (seconds)

The full flag catalogue, including the standard node arguments shared with validator mode, lives in the Kona node CLI reference.

Example Configurations

Basic Sequencer

kona-node node \
  --mode=Sequencer \
  --l1-eth-rpc=http://localhost:8545 \
  --l1-beacon=http://localhost:5052 \
  --l2-engine-rpc=http://localhost:8551 \
  --chain=42161

Sequencer with Conductor

kona-node node \
  --mode=Sequencer \
  --conductor.rpc=http://conductor:8080 \
  --conductor.rpc.timeout=5 \
  --sequencer.l1-confs=6 \
  --l1-eth-rpc=http://l1-node:8545 \
  --l1-beacon=http://l1-beacon:5052 \
  --l2-engine-rpc=http://l2-execution:8551 \
  --chain=123456

Recovery Mode Sequencer

kona-node node \
  --mode=Sequencer \
  --sequencer.recover=true \
  --sequencer.max-safe-lag=100 \
  --l1-eth-rpc=http://localhost:8545 \
  --l1-beacon=http://localhost:5052 \
  --l2-engine-rpc=http://localhost:8551 \
  --chain=42161

Key Considerations

Sequencer Operation

L1 Confirmations: The --sequencer.l1-confs setting determines how many L1 blocks the sequencer waits before using an L1 block as an origin. Higher values provide more safety but increase latency.
Recovery Mode: Use --sequencer.recover=true when the sequencer needs to catch up after being offline.
Conductor Integration: For multi-sequencer deployments, configure the conductor service for proper leader election.

Running a sequencer in production requires careful consideration of infrastructure, monitoring, and failover procedures. Ensure proper JWT secret management and secure network configuration.

​Basic Sequencer Setup

​Required Arguments

​Sequencer-Specific Flags

​Example Configurations

​Basic Sequencer

​Sequencer with Conductor

​Recovery Mode Sequencer

​Key Considerations

Basic Sequencer Setup

Required Arguments

Sequencer-Specific Flags

Example Configurations

Basic Sequencer

Sequencer with Conductor

Recovery Mode Sequencer

Key Considerations