A Circuit Breaker in Go: Build One in 100 Lines, Then Reach for gobreaker

Short summary

A circuit breaker protects distributed systems from cascading failures by quickly rejecting calls to failing dependencies instead of waiting for timeouts that drain connection pools and crash upstream services. This post builds a working implementation in ~100 lines of Go, explaining the three-state machine (Closed for normal operation, Open to reject calls, Half-Open to test recovery). The author then demonstrates why you'd reach for the mature gobreaker library in production.

• •Build a working circuit breaker in ~100 lines of Go with mutex-guarded state management
• •Pattern transitions through three states: Closed (normal) → Open (reject all) → Half-Open (test recovery)
• •Shows how one slow dependency causes cascading timeouts; recommends gobreaker library for production

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