Relay multiplexing

[faheelsattar]

📝 Summary

Introduces a muxing feature to mev-boost that enables different sets of validators to connect to different sets of relays. This addresses a significant operational need for large-scale validator operations.

See also: https://collective.flashbots.net/t/muxing-in-mev-boost-to-handle-diverse-relay-sets/5231/2

Each policy contains:

• name: a unique identifier for the policy
• relayers: a list of relay configurations including:
  • name: relay identifier
  • url: the relay endpoint URL
  • http-header: optional custom http headers

Each mapping contains:

• name: name for the mapping
• policy: references a policy defined in the policies section
• filters: criteria for selecting which validators use this policy:
  • public_keys: list of validator public keys

Example config:

policies:
  - name: "lido-policy"
    relayers:
      - name: "relayer-1"
        url: "0x9000009807ed12c1f08bf4e81c6da3ba8e3fc3d953898ce0102433094e5f22f21102ec057841fcb81978ed1ea0fa8246@relay.relayer1.net"
      - name: "relayer-2"
        url: "0x9000009807ed12c1f08bf4e81c6da3ba8e3fc3d953898ce0102433094e5f22f21102ec057841fcb81978ed1ea0fa8246@relay.relayer2.com"
        http-header:
          X-Custom-Header: "custom-value"
  - name: "rocket-pool-policy"
    relayers:
      - name: "relayer-1"
        url: "0x9000009807ed12c1f08bf4e81c6da3ba8e3fc3d953898ce0102433094e5f22f21102ec057841fcb81978ed1ea0fa8246@relay.relayer1.io"
      - name: "relayer-2"
        url: "0x9000009807ed12c1f08bf4e81c6da3ba8e3fc3d953898ce0102433094e5f22f21102ec057841fcb81978ed1ea0fa8246@relay.relayer2.com"

mappings:
  - name: "lido-validators"
    policy: "lido-policy"
    filters:
      public_keys:
        - "0x8a1d7b8dd64e0aafe7ea7b6c95065c9364cf99d38470c12ee807d55f7de1529ad29ce2c422e0b65e3d5a05c02caca249"
        - "0x8b1d7b8dd64e0aafe7ea7b6c95065c9364cf99d38470c12ee807d55f7de1529ad29ce2c422e0b65e3d5a05c02caca250"
        - "0x8c1d7b8dd64e0aafe7ea7b6c95065c9364cf99d38470c12ee807d55f7de1529ad29ce2c422e0b65e3d5a05c02caca251"
  - name: "rocket-pool-validators"
    policy: "rocket-pool-policy"
    filters:
      public_keys:
        - "0x8d1d7b8dd64e0aafe7ea7b6c95065c9364cf99d38470c12ee807d55f7de1529ad29ce2c422e0b65e3d5a05c02caca252"
        - "0x8e1d7b8dd64e0aafe7ea7b6c95065c9364cf99d38470c12ee807d55f7de1529ad29ce2c422e0b65e3d5a05c02caca253"
        - "0x8f1d7b8dd64e0aafe7ea7b6c95065c9364cf99d38470c12ee807d55f7de1529ad29ce2c422e0b65e3d5a05c02caca254"

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✅ I have run these commands

• make lint
• make test-race
• go mod tidy

[Copilot]

Pull Request Overview

This PR introduces validator-to-relay muxing functionality in mev-boost, allowing different sets of validators to be associated with specific sets of relays rather than sending all validator requests to all relays.

• Adds a new MuxConfig structure to define policies and validator mappings
• Modifies validator registration and header/payload requests to use validator-specific relays
• Adds configuration loading and validation for YAML-based mux configuration files

Reviewed Changes

Copilot reviewed 9 out of 10 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
server/service.go	Adds mux configuration support to BoostService with relay selection logic
server/register_validator.go	Implements validator-specific relay routing for registration requests
server/mux_test.go	Comprehensive test coverage for the muxing functionality
server/get_payload.go	Updates payload requests to use policy-based relay selection
server/get_header.go	Modifies header requests to use validator-specific relays
config/mux_config.go	Core mux configuration structure with YAML loading and validation
cli/main.go	Integrates mux config setup into CLI initialization
cli/flags.go	Adds command-line flag for mux configuration file path
go.mod	Updates yaml.v3 dependency to direct import

Comments suppressed due to low confidence (1)

server/register_validator.go:1

• Silent error handling here swallows potentially important configuration errors. Consider logging the error to help with debugging mux configuration issues.

package server

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