Skip to main content
op-conductor is the OP Stack’s high-availability sequencer coordination service: it manages a cluster of sequencers so that exactly one leads the chain at a time and block production survives single-node failures.

​
Overview

op-conductor runs alongside each sequencer in a multi-node cluster, typically three nodes spread across regions or availability zones. It participates in a Raft consensus layer to elect the leader and to store the latest unsafe block, monitors its sequencer’s health, starts or stops sequencing based on leadership and health, and serves admin RPCs for manual recovery scenarios. The design provides three guarantees: no unsafe reorgs, no unsafe head stall during a network partition, and continued uptime with no more than one node failure in a standard three-node setup. For how this works in detail, see the OP Conductor explainer. It exists because a single sequencer is a single point of failure: without coordination, a crashed sequencer halts block production, and a naive failover can produce two active sequencers or reorg unsafe blocks. op-conductor is not Byzantine fault tolerant: it assumes all participating nodes are honest, performs no authentication or authorization of RPC requests, and is intended to run inside a private network. Who runs it: chain operators running a high-availability sequencer setup, with one conductor instance per sequencer node. The rollup node’s sequencer mode integrates with it on both op-node (--conductor.enabled and --conductor.rpc) and kona-node (--conductor.rpc). Chains running a single sequencer do not need it.

​
Get started

  • Setup: add op-conductor to an existing multi-sequencer OP Stack network without downtime.

​
How-tos

​
Configuration & flags reference

  • Configuration and RPCs: every CLI flag and environment variable, with flag tables generated from the op-conductor release named on the page, plus the conductor namespace RPC methods for cluster management.

​
Releases

  • Source: op-conductor/ in the Optimism monorepo; its README documents the architecture, the conductor state transitions, and walkthroughs of each failure scenario.
  • op-conductor is operational tooling and has no section of its own in the OP Stack specifications; the sequencing role it coordinates is specified in the rollup node specification.