Config file support for relays + builder aliases. Defaults for mainnet and hoodi

[metachris]

This pull request migrates the relay URLs and builder addresses configuration from hardcoded Go files to external YAML config files, improving flexibility and maintainability. It introduces a new configuration loading mechanism, updates the CLI to support custom config files, and refactors related variables to be populated from the config at runtime. The changes also add sample config files for mainnet and Hoodi networks.

Configuration management improvements:

• Introduced a new vars/config.go file with a Config struct and LoadConfig function to load relay URLs, builder addresses, and genesis timestamp from a YAML config file. The config is loaded at startup and populates package-level variables for backwards compatibility.
• Refactored vars/relays.go and vars/builder_addresses.go to remove hardcoded relay URLs and builder addresses, making them populated from the loaded config file instead. [1] [2]
• Updated vars/vars.go to set the Genesis variable from the config file rather than an environment variable or hardcoded value.

CLI and usage documentation updates:

• Modified cmd/root.go to add a --config flag and support the CONFIG_FILE environment variable, defaulting to config-mainnet.yaml if unspecified. The config file is loaded before running any command.
• Updated README.md to document the new config file system, including usage examples for specifying custom config files.

New configuration files:

• Added config-mainnet.yaml and config-hoodi.yaml as example configuration files for mainnet and Hoodi networks, respectively. These files define relay URLs, genesis timestamps, and builder addresses in YAML format. [1] [2]

Dependency management:

• Added gopkg.in/yaml.v3 as a direct dependency in go.mod for YAML parsing, and removed it from the indirect dependencies list. [1] [2]

[Copilot]

Pull request overview

This PR introduces configuration file support for relay URLs and builder addresses, migrating them from hardcoded Go variables to YAML files. The changes enable network-specific configurations with default support for mainnet and hoodi testnet.

Key Changes:

• Replaced hardcoded relay URLs and builder addresses with YAML-based configuration
• Added config loader with support for CLI flag and environment variable
• Created default configurations for mainnet and hoodi networks

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
vars/vars.go	Changed Genesis from environment variable to config file value
vars/relays.go	Converted hardcoded relay URLs to config-populated variables
vars/config.go	Added new config loader with YAML parsing and variable population
vars/builder_addresses.go	Converted hardcoded builder addresses to config-populated variable
go.mod	Moved yaml.v3 dependency from indirect to direct
config-mainnet.yaml	Added mainnet configuration with relay URLs and builder addresses
config-hoodi.yaml	Added hoodi testnet configuration
cmd/root.go	Added config file flag and loading in PersistentPreRunE
README.md	Updated documentation to reference config files

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