Middleware guides

Middleware - Logger

Detailed guide to Kern.Logger middleware with config options and production logging examples for Go API servers.

Kern.Logger

kern.Logger logs request method, path, status, duration, and response size.

Signature

func Logger(configs ...LoggerConfig) MiddlewareFunc

Common config options

Format: text or json
Output: custom writer destination
SLogger: structured logger backend (*slog.Logger)
Fields: static fields to attach to all request logs

Example

app := kern.New()
app.Use(kern.Logger(kern.LoggerConfig{
    Format: "json",
    Fields: map[string]interface{}{
        "service": "users-api",
        "env": "prod",
    },
}))

Best practices

Place logger early in global middleware chain.
Add request IDs before logger if you want correlation IDs in logs.

Architecture Flow

Understand the end-to-end request and response flow in Kern, including net/http entry, middleware order, route matching, context reuse, handler execution, and response writes.

Middleware - Recovery

Detailed guide to Kern.Recovery middleware for panic-safe request handling in production Go services.

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Kern.Logger Signature Common config options Example Best practices