Spring Boot & Resilience4j - Mastering circuit breakers with Prometheus and Grafana
A comprehensive guide to implementing resilient microservices: from basic circuit breaker patterns to advanced monitoring with Prometheus and Grafana
Introduction
Imagine you’re building a microservice—based application where many services depend on each other. What happens when one service strt failing? Without proper error handling, failures can cascade through your system. They could bring down the entire application. This is where circuit breaker pattern comes in.
Understanding the circuit breaker pattern
Michael Nygard popularized the circuit breaker pattern in “Release It!”. It prevents cascading failures and provide a fallback when integrations fail. It works like an electrical circuit breaker—when it detects a problem, it stops the flow to protect the system.
The pattern has three states:
Closed — In this state, all calls go through without interruption. If the number of failures exceeds a threshold, the circuit move to the open state.
Open — When in this state, calls are not made to the failing service. Instead, a fallback mechanism is used. After a timeout period, the circuit moves to half-open state.
Half—open — the system allows. limited number of test call through to check if the service has recovered. If these calls succeed, the circuit moves back to closed state. If they fail, it returns to open state.