# Builder Modifications (15 minutes)

In this document, we provide both a general overview of the small changes needed to a Geth instance to enable Primev. We will go through a standard fork of the Flashbots builder, and walk through the changes that need to be made. We also provide a general overview if your Geth instance has significant changes from the Flashbots builder.

> Please reach out to us if you need any assistance

### Overview

Builder-boost sits as a sidecar to your execution client. Builder will consistently spin up lightweight go-routines to POST new templates.

# Quickstart (5 mins)

If you want to use the off the shelf instance of our Builder Reference Implementation, you can do the following 2 steps.

1. Clone the repository from https://github.com/primevprotocol/builder-reference-primev
2. Build the instance and add with the flag `--builder.remote_primev_endpoint <your-builder-boost-url> --builder.primev_token <your-selected-private-token>`

# (Advanced) Optional Instructions

## General Overview of Changes Needed

The idea behind what we’re doing is to enable a new relay to publish our blocks to, in a very similar fashion to how blocks are committed to a flashbots relay.

Below is a more detailed perspective of the standard flow in the Flashbots builder. If you observe, we add a command of `go SubmitBlockPrimev(&blockData)` in the SubmitBlock section.

Most geth instances will have some concept of a IRelay, you simply need to add a `SubmitBlockPrimev` to such a relay that is in use, and configure any of the necessary configurations via modifications similar to this commit: https://github.com/primevprotocol/builder-reference-primev/commit/9f160e8934fef1aadd21e095c432db41538b93af

## Step by Step Walkthrough

## Step 1. Registering the Builder Boost environment variables

#### Step 1a. Primev Endpoint

You can view the entire commit for this section below.

[https://github.com/primevprotocol/builder-reference-primev/commit/9f160e8934fef1aadd21e095c432db41538b93af](https://github.com/primevprotocol/builder-reference-primev/commit/9f160e8934fef1aadd21e095c432db41538b93af)

By the end of this, you can build geth and you will see the following output:

**WARN [timestamp] Remote Primev Endpoint is not Set, payloads will not be sent to Primev Network**

If you set the correct environment variable `BUILDER_REMOTE_PRIMEV_ENDPOINT` or pass in the flag `builder.remote_primev_endpoint` while running geth, you’ll see the following successful message:

**INFO [timestamp] Remote Primev Endpoint is Set, payloads will be sent to Primev Network endpoint=<Your builder boost URL>**

#### Step 1b. Primev Token
The **primev token** is used to *authorize* and *authenticate* the buidler instance. This is to ensure only your builders can post payloads to Boost.

The following link showcases the necessary modifications to setup the Primev Token:

https://github.com/primevprotocol/primev-builder/commit/d9b8addd1fdeea8c841a43ff7653e7c9345e7e0d

We will describe below in Step 3, how to submit the request, ensure you make the modification to add the `X-BUILDER-TOKEN: <primev-token>` header to the POST reqest that is made to Boost.

## Step 2. Updating the Relay Interface to support Block Submission to Primev/Builder Boost

In this commit we simply add in all the required function details to support updating the Relay interface to publish to Builder Boost.

[https://github.com/primevprotocol/builder-reference-primev/commit/6d8ae9aae17a1b966ac0f682ba9843bd8746dc4f](https://github.com/primevprotocol/builder-reference-primev/commit/6d8ae9aae17a1b966ac0f682ba9843bd8746dc4f)

## Step 2a. Update interface needs for Unit Tests

Follow the commit to add a stub for the `testRelay` to ensure it adheres to the new interface

[https://github.com/primevprotocol/builder-reference-primev/commit/122e82ee6072ff2cda94ed8e75fdd861befccd19](https://github.com/primevprotocol/builder-reference-primev/commit/122e82ee6072ff2cda94ed8e75fdd861befccd19)

## Step 3. Start Submitting blocks to Builder Boost

Finally in the following commit we submit the block details via a go-routine to ensure we don’t block for the response.

[https://github.com/primevprotocol/builder-reference-primev/commit/04d81efdf499ada3cee303316665edf0d5945a27](https://github.com/primevprotocol/builder-reference-primev/commit/04d81efdf499ada3cee303316665edf0d5945a27)