logging

name	Logging
description	Standards for structured logging and observability in Golang.
metadata	{"labels":["golang","logging","slog","zap","observability"],"triggers":{"files":["go.mod","pkg/logger/**"],"keywords":["logging","slog","structured logging","zap"]}}

Golang Logging Standards

Priority: P1 (STANDARD)

Principles

• Structured Logging: Use JSON or structured text. Readable by machines and humans.
• Leveled Logging: Debug, Info, Warn, Error.
• Contextual: Include correlation IDs (TraceID, RequestID) in logs.
• No log.Fatal: Avoid terminating app inside libraries. Return error instead. Only main should exit.

Libraries

• log/slog (Recommended): Stdlib since Go 1.21. Fast, structured, zero-dep.
• Zap (uber-go/zap): High performance, good if pre-1.21 or extreme throughput needed.
• Zerolog: Zero allocation, fast JSON logger.

Guidelines

• Initialize logger at startup.
• Inject logger or use a global singleton configured at startup (pragmatic choice).
• Use slog.Attr for structured data.

References

• Slog Patterns