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Service-Level “Circuit Breaker” (Simple)

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                  class CircuitBreaker
  def initialize(name, redis: Redis.current)
    @name = name
    @redis = redis
  end

  def allow?
    @redis.get(open_key).nil?
  end

  def record_failure!(cooldown: 30)
    @redis.set(open_key, '1', ex: cooldown)
  end

  private

  def open_key
    "cb:open:#{@name}"
  end
end

                    breaker = CircuitBreaker.new('shipping_api')
  raise 'Dependency temporarily unavailable' unless breaker.allow?

  ShippingProvider.new.quote(...)
rescue Faraday::Error
  breaker.record_failure!(cooldown: 60)
  raise

When a dependency is failing, you don’t want to keep hammering it. A simple circuit breaker trips after N failures and short-circuits for a cooldown window. It protects your app and your vendor.

Sarah Chen

More from Sarah Chen

Service-Level “Circuit Breaker” (Simple)

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More from Sarah Chen