Skip to content

Set up block builders / MEV

Nimbus supports outsourcing block production to an external block builder, thus presenting the opportunity to capture Maximal Extractable Value (MEV).

When external block building is enabled, the beacon node connects to a service using the builder API with the execution client acting as a fallback.

Setting up external block building typically involves running an additional service on your server which is configured to choose the best block from one or more relays and having the beacon node connect to this service.

Warning

External block builders introduce additional risk to the block building process which may cause loss of rewards.

In particular, once Nimbus has signed the block header proposed by the external builder, the execution client can no longer be used as fallback and the external builder is trusted to complete the building process.

Note

By default, priority and maximum gas fees determine transaction inclusion in blocks.

External block builders may use other strategies for transaction selection, including regulatory constraints and extracted value. For further information, check the documentation of the block builder.

Command line

External block building is must be enabled on both beacon node and validator client using the --payload-builder=true flag.

Additionally, the URL of the service exposing the builder API must be provided to the beacon node:

./run-mainnet-beacon-node.sh --payload-builder=true --payload-builder-url=https://${HOST}:${PORT}/
./run-prater-beacon-node.sh --payload-builder=true --payload-builder-url=https://${HOST}:${PORT}/
build/nimbus_validator_client --payload-builder=true

Useful resources