Systems

The systems lens covers Caddy's architectural building blocks — the parts of the core that do not ship as user-facing apps but that hold everything together. These live mostly in the top-level caddy package.

Pages

• Module system — caddy.RegisterModule, namespaces, LoadModule, lifecycle interfaces
• Admin API — localhost:2019, /load, /config, AdminRouter
• Replacer — placeholder substitution ({http.request.uri}, {env.HOME}, …)
• Listeners — caddy.Listen, listener wrappers, graceful reload
• Context — caddy.Context, app/module lookup, scoped loggers
• Storage — certmagic.Storage integration, default file storage
• Logging system — zap logger tree, encoders and writers

These topics often overlap. The Context is how modules reach the module system; the module system is what the admin API and Caddyfile both ultimately drive; the replacer is how almost every config field becomes runtime-aware. Read them in any order.