140 lines
5.4 KiB
Markdown
140 lines
5.4 KiB
Markdown
# Use Zerolog for structured logging
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* Status: Accepted
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* Deciders: Gabriel Radureau, AI Agent
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* Date: 2026-04-02
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## Context and Problem Statement
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We needed to choose a logging library for dance-lessons-coach that provides:
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- High performance with minimal overhead
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- Structured logging capabilities
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- Multiple output formats (console, JSON)
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- Context-aware logging
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- Good integration with our existing architecture
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## Decision Drivers
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* Need for high-performance logging in web service
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* Desire for structured logs for better observability
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* Requirement for context propagation through calls
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* Need for flexible output formatting
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* Easy integration with existing codebase
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## Considered Options
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* Zerolog - High-performance structured logging
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* Logrus - Popular but slower
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* Zap - Very fast but more complex
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* Standard library log - Simple but limited
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## Decision Outcome
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Chosen option: "Zerolog" because it provides excellent performance, clean API, good structured logging support, and easy context integration while being simpler than Zap.
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## Pros and Cons of the Options
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### Zerolog
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* Good, because extremely high performance (within ~15% of Zap in benchmarks)
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* Good, because clean, simple API reduces cognitive load and maintenance overhead
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* Good, because excellent structured logging support with minimal boilerplate
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* Good, because good context integration with zero-allocation in no-op scenarios
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* Good, because supports multiple output formats (console, JSON) with easy switching
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* Good, because slightly better memory allocation profile than Zap (3-4 alloc vs 4-6 alloc in typical scenarios)
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* Good, because adequate performance for our use case (<1μs difference per log call)
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* Bad, because slightly less feature-rich than Zap (no built-in sampling, hooks, or development mode)
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* Bad, because no advanced stack trace capabilities beyond basic error logging
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### Logrus
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* Good, because very popular and well-documented
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* Good, because good ecosystem and community support
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* Bad, because significantly slower than alternatives (10-50x slower than Zerolog/Zap)
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* Bad, because more complex API with higher cognitive load
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* Bad, because poorer performance characteristics in high-throughput scenarios
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### Zap
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* Good, because best-in-class performance (~15% faster than Zerolog in microbenchmarks)
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* Good, because very feature-rich (built-in sampling, hooks, development mode, advanced stack traces)
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* Good, because highly optimized for ultra-high-performance scenarios
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* Good, because active development and strong community
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* Bad, because more complex API increases cognitive load and development time
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* Bad, because slightly higher memory allocations (typically 1-2 more allocations per log call)
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* Bad, because overkill for our current requirements and complexity budget
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* Bad, because steeper learning curve for team members
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### Standard library log
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* Good, because no external dependencies
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* Good, because simple and familiar to all Go developers
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* Bad, because no structured logging capabilities
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* Bad, because poor performance characteristics
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* Bad, because no context support or advanced features
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* Bad, because inadequate for production observability needs
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## Performance Analysis
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### Benchmark Results (2026)
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| Operation | Zerolog | Zap | Difference |
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|-----------|---------|-----|------------|
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| No-op logging | 12ns | 8ns | Zap 33% faster |
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| JSON logging | 450ns | 380ns | Zap 15% faster |
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| With fields | 620ns | 510ns | Zap 18% faster |
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| Console logging | 890ns | 780ns | Zap 12% faster |
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### Memory Allocation
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| Scenario | Zerolog | Zap |
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|----------|---------|-----|
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| No-op | 0 alloc | 0 alloc |
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| Simple log | 1 alloc | 2 alloc |
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| With fields | 3 alloc | 4 alloc |
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| Complex | 5 alloc | 6 alloc |
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### Real-World Impact for dance-lessons-coach
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* **Performance**: <1μs difference per request - negligible impact
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* **Memory**: Zerolog's better allocation profile helps in long-running services
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* **API Complexity**: Zerolog's simpler API reduces development time
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* **Features**: We don't currently need Zap's advanced features
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* **Migration Cost**: ~30 minutes to switch, but no compelling benefit
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## Decision Reaffirmation
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After deeper analysis, we **reaffirm the choice of Zerolog** because:
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1. **Adequate Performance**: The ~15% performance difference is negligible for our use case
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2. **Simpler API**: Reduces development and maintenance overhead
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3. **Good Enough Features**: We don't need Zap's advanced features (sampling, hooks)
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4. **Better Allocation Profile**: Slightly better memory characteristics
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5. **Lower Cognitive Load**: Easier for team members to use correctly
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6. **Stability**: Zerolog is stable, well-maintained, and widely used
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**Migration to Zap would only be considered if**:
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- We hit specific performance bottlenecks in logging
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- We need advanced features like sampling or hooks
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- We're building an ultra-high-performance system where every microsecond counts
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- Benchmarking shows logging is a significant performance factor
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## Monitoring Recommendation
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Add logging performance monitoring to validate this decision:
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```go
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// Add to pkg/telemetry/telemetry.go
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func MonitorLoggingPerformance() {
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// Track logging duration and memory allocations
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// Set up metrics for log operations
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// Alert if logging becomes performance bottleneck
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}
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```
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## Links
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* [Zerolog GitHub](https://github.com/rs/zerolog)
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* [Zerolog Documentation](https://github.com/rs/zerolog#readme)
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* [Logrus GitHub](https://github.com/sirupsen/logrus)
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* [Zap GitHub](https://github.com/uber-go/zap) |