How to determine that microservices are functioning correctly?

Several key approaches are used to determine the correct operation of microservices:

• Health checks — endpoints that return the service status (e.g., HTTP 200 OK), allowing quick understanding that the service is available and functioning.
• Logging — collecting and analyzing logs helps identify errors and anomalies in service operation.
• Metrics — gathering indicators (latency, request count, errors) using monitoring systems (Prometheus, Grafana) to track performance and stability.
• Tracing — distributed tracing systems (Jaeger, Zipkin) help understand how requests pass through different services, identify bottlenecks and failures.
• Monitoring and alerting — setting up notifications for deviations from norms (e.g., increased errors or decreased performance).

Example of a simple health check in PHP:

// health.php
header('Content-Type: application/json');
// checks for database connection, external services, etc. can be added
echo json_encode(['status' => 'ok']);

Thus, the combination of these tools and practices allows timely detection and resolution of problems in a microservice architecture.