# Start Your Engine API for Merge™

**Published by:** [detoo](https://paragraph.com/@detoo-2/)
**Published on:** 2022-09-04
**URL:** https://paragraph.com/@detoo-2/start-your-engine-api-for-merge

## Content

--authrpc.port=8551Merge™ is coming. Most of us have probably already heard of the renaming and the introduction of Execution Client (ex. Geth) and the Consensus Client (ex. Lighthouse Beacon Node). It also introduced a new interface called Engine API. As a pre-merge validator, what exactly has changed? How do I upgrade it and verify if it is ready for merge?Below assumes we have existing (pre-merge) nodes running and will focus only on the changes.Execution ClientThere are multiple options for running an Execution Client. I’ll focus on geth here. The current merge-ready geth version is v1.10.23 as of writing. Upgrading from a pre-merge geth version you need to add the following arguments:--authrpc.addr=localhost --authrpc.port=8551 Note if you are running Beacon nodes or Validator nodes in a container, you might want to add the extra arguments so that incoming requests from virtual hosts are accepted:--authrpc.vhosts="*" Restart geth, if everything runs properly you will see:WARN Chain pre-merge, sync via PoW (ensure beacon client is ready) ... WARN Engine API enabled protocol=eth WARN Engine API started but chain not configured for merge yet ... INFO Generated JWT secret path=/home/you/.ethereum/geth/jwtsecret ... INFO WebSocket enabled url=ws://127.0.0.1:8551 INFO HTTP server started endpoint=127.0.0.1:8551 auth=true prefix= cors=localhost vhosts=* Note the pre-merge status and the generated JWT secret location in the logs.Consensus Client (Beacon Node)Again there are multiple options for running a Beacon Node, here I will use Lighthouse. As of writing, the current merge-ready Lighthouse version is v3.1.0. Add the following merge-related arguments:--execution-endpoints http://localhost:8551 --execution-jwt="/home/you/.ethereum/geth/jwtsecret" Note the port 8551 is different from the legacy RPC port (8545) because it is an exclusive interface for the Beacon Node only. Also note the --execution-jwt location should match the location shown in geth logs above. Restart the Beacon Node. It will take a few minutes to migrate the database from the previous version. Once it is connected and synced with the Execution Client we’ll see:INFO Ready for the merge current_difficulty: 57833190587477479896205, terminal_total_difficulty: 58750000000000000000000, service: slot_notifier That means both clients are ready! The Engine API has started, the TTD (Terminal Total Difficulty) is nominal, we are ready for Merge™One More ThingGo to bordel.wtf and check out the estimated Merge time if you want to see it happen live!

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