Error Handling

The router package integrates directly with Go’s standard log/slog ecosystem.

Application errors, startup failures, and recovered panics can be logged using structured logging handlers such as:

• github.com/netlifeguru/logger
• custom slog.Handler
• JSON loggers
• external observability systems

This allows production applications to store structured error logs in machine-readable formats for monitoring and debugging.

Startup Errors

Server startup failures should always be checked.

Example:

if err := r.ListenAndServe(":8000"); err != nil {
	slog.Error("failed to start server", "error", err)
	os.Exit(1)
}

This logs startup errors such as:

• port conflicts
• permission issues
• invalid listener configuration
• TLS failures

Structured JSON Logging

When used together with github.com/netlifeguru/logger, errors are automatically written into rotating JSON log files.

Example logger setup:

closer, err := logger.Init(logger.Config{
	Dir:            "./logs",
	TerminalOutput: true,
})

Example log file:

./logs/2026-05-12-0001.log

Example structured error log:

{
  "time": "2026-05-12T21:43:02+02:00",
  "level": "ERROR",
  "msg": "failed to start server",
  "error": "listen tcp :8000: bind: address already in use"
}

Structured logs make it easier to integrate with:

• Elasticsearch
• Loki
• Datadog
• Grafana
• Splunk
• cloud logging systems

Panic Recovery Logging

Recovered panics are also logged automatically through slog.

Example panic:

panic("database connection lost")

Example log output:

{
  "time": "2026-05-12T21:50:11+02:00",
  "level": "ERROR",
  "msg": "panic recovered",
  "panic": "database connection lost"
}

This allows applications to capture unexpected runtime failures without crashing the server process.

Terminal vs File Logging

When terminal output is enabled:

TerminalOutput: true

errors are shown in the console with colorized formatting.

Example:

2026-05-12 21:43:02 [ERROR] failed to start server error="bind: address already in use"

At the same time, the same event is safely written into structured JSON log files.

Recommended Production Setup

Recommended production configuration:

logger.Init(logger.Config{
	Dir:             "./logs",
	TerminalOutput:  false,
	MinLevel:        slog.LevelInfo,
	ConsoleMinLevel: slog.LevelError,
})

This configuration:

• stores structured logs in files
• reduces terminal noise
• keeps error logs centralized
• enables long-term log retention

Notes

The router itself does not force a logging implementation.

All logging flows through Go’s standard log/slog package, allowing applications to fully control:

• formatting
• storage
• rotation
• transports
• observability integrations
• structured metadata