Request Log

Documentation Index

Fetch the complete documentation index at: https://docs.go-mizu.dev/llms.txt

Use this file to discover all available pages before exploring further.

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Overview

• Structured request logs
• Detailed debugging info
• Log aggregation integration

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Installation

import "github.com/go-mizu/mizu/middlewares/requestlog"

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Quick Start

app := mizu.New()

app.Use(requestlog.New())

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Configuration

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Options

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Examples

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Default Logging

app.Use(requestlog.New())

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With slog

logger := slog.New(slog.NewJSONHandler(os.Stdout, nil))

app.Use(requestlog.WithLogger(logger))

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Custom Fields

app.Use(requestlog.WithOptions(requestlog.Options{
    Fields: []string{
        "method",
        "path",
        "status",
        "latency",
        "ip",
        "user_agent",
    },
}))

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Skip Health Checks

app.Use(requestlog.WithOptions(requestlog.Options{
    Skip: func(c *mizu.Ctx) bool {
        return c.Request().URL.Path == "/health"
    },
}))

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Error Level for Errors

app.Use(requestlog.WithOptions(requestlog.Options{
    LevelFunc: func(status int) slog.Level {
        if status >= 500 {
            return slog.LevelError
        }
        if status >= 400 {
            return slog.LevelWarn
        }
        return slog.LevelInfo
    },
}))

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Log Output

{
    "time": "2024-01-15T10:30:00Z",
    "level": "INFO",
    "msg": "request",
    "method": "GET",
    "path": "/api/users",
    "status": 200,
    "latency": "1.234ms",
    "ip": "192.168.1.1",
    "user_agent": "Mozilla/5.0..."
}

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API Reference

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Functions

// New creates request log middleware
func New() mizu.Middleware

// WithLogger creates with custom logger
func WithLogger(logger *slog.Logger) mizu.Middleware

// WithOptions creates with configuration
func WithOptions(opts Options) mizu.Middleware

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Technical Details

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Implementation

• Timing: Uses time.Now() and time.Since() to measure request duration with nanosecond precision
• Skip Logic: Pre-computes skip paths and methods into maps for O(1) lookup performance
• Body Preservation: Reads request body using io.LimitReader and restores it with io.NopCloser(bytes.NewReader(body)) to allow downstream handlers to access it
• Header Redaction: Maintains a map of sensitive header names for constant-time redaction checks
• Default Values: Automatically sets default logger (text handler to stdout), max body size (4KB), and sensitive headers (Authorization, Cookie, X-API-Key)

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Logged Fields

• method: HTTP method (GET, POST, etc.)
• path: Request URL path
• remote_addr: Client remote address
• query: Raw query string (only if present)
• headers: Request headers (only if LogHeaders: true)
• body: Request body up to MaxBodySize (only if LogBody: true)
• duration: Request processing duration
• error: Error message (only if request returns an error)

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Error Handling

• The error is logged at ERROR level with all request attributes
• The error is propagated to the next middleware (not swallowed)
• Request duration is still calculated and logged

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Security Considerations

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Sensitive Data Protection

• Default sensitive headers: Authorization, Cookie, X-API-Key
• Custom sensitive headers can be configured via SensitiveHeaders option
• Redacted headers show [REDACTED] in logs

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Body Logging Risks

• Request bodies may contain passwords, tokens, or PII
• Body size is limited by MaxBodySize (default 4KB) to prevent memory exhaustion
• Consider using skip logic for authentication endpoints
• Review compliance requirements (GDPR, HIPAA, etc.) before enabling

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Best Practices

• Use structured logging for aggregation
• Skip noisy endpoints
• Include request IDs for correlation
• Set appropriate log levels
• Be cautious with LogBody on production systems
• Configure SensitiveHeaders for your application’s needs
• Use SkipPaths for health checks and metrics endpoints
• Set reasonable MaxBodySize limits to prevent memory issues

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Testing

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Related Middlewares

• logger - Simple logging
• audit - Audit logging
• requestid - Request IDs