Monitoring Service Health

Health check in microservices refers to a mechanism or process implemented within each service to assess its operational status and readiness to handle requests. It involves regularly querying the service to determine if it is functioning correctly, typically by evaluating its responsiveness and ability to perform essential tasks. Health checks play a critical role in ensuring service availability, detecting failures, preventing cascading issues, and facilitating effective traffic routing in distributed systems.

GoFr by default registers two endpoints which are:

1. Aliveness - /.well-known/alive

It is an endpoint which returns the following response with a 200 status code, when the service is UP.

{
  "data": {
    "status": "UP"
  }
}

It is also used when state of circuit breaker is open.

To override this endpoint, pass the following option while registering HTTP Service:

&service.HealthConfig{
			HealthEndpoint: "breeds",
		}

2. Health-Check - /.well-known/health

It is an endpoint which returns whether the service is UP or DOWN along with stats, host, status about the dependent datasources and services.

Sample response of how it appears when all the services, and connected data sources are UP:

{
  "data": {
    "anotherService": {
      "status": "UP",
      "details": {
        "host": "localhost:9000"
      }
    },
    "redis": {
      "status": "UP",
      "details": {
        "host": "localhost:2002",
        "stats": {
          "active_defrag_hits": "0",
          "active_defrag_key_hits": "0",
          "active_defrag_key_misses": "0",
          "active_defrag_misses": "0",
          "current_active_defrag_time": "0",
          "current_eviction_exceeded_time": "0",
          "dump_payload_sanitizations": "0",
          "evicted_clients": "0",
          "evicted_keys": "0",
          "expire_cycle_cpu_milliseconds": "1",
          "expired_keys": "0",
          "expired_stale_perc": "0.00",
          "expired_time_cap_reached_count": "0",
          "instantaneous_input_kbps": "0.00",
          "instantaneous_input_repl_kbps": "0.00",
          "instantaneous_ops_per_sec": "0",
          "instantaneous_output_kbps": "0.00",
          "instantaneous_output_repl_kbps": "0.00",
          "io_threaded_reads_processed": "0",
          "io_threaded_writes_processed": "0",
          "keyspace_hits": "0",
          "keyspace_misses": "0",
          "latest_fork_usec": "0",
          "migrate_cached_sockets": "0",
          "pubsub_channels": "0",
          "pubsub_patterns": "0",
          "pubsubshard_channels": "0",
          "rejected_connections": "0",
          "reply_buffer_expands": "0",
          "reply_buffer_shrinks": "1",
          "slave_expires_tracked_keys": "0",
          "sync_full": "0",
          "sync_partial_err": "0",
          "sync_partial_ok": "0",
          "total_active_defrag_time": "0",
          "total_commands_processed": "2",
          "total_connections_received": "1",
          "total_error_replies": "2",
          "total_eviction_exceeded_time": "0",
          "total_forks": "0",
          "total_net_input_bytes": "183",
          "total_net_output_bytes": "257",
          "total_net_repl_input_bytes": "0",
          "total_net_repl_output_bytes": "0",
          "total_reads_processed": "5",
          "total_writes_processed": "4",
          "tracking_total_items": "0",
          "tracking_total_keys": "0",
          "tracking_total_prefixes": "0",
          "unexpected_error_replies": "0"
        }
      }
    },
    "sql": {
      "status": "UP",
      "details": {
        "host": "localhost:2001/test",
        "stats": {
          "maxOpenConnections": 0,
          "openConnections": 1,
          "inUse": 0,
          "idle": 1,
          "waitCount": 0,
          "waitDuration": 0,
          "maxIdleClosed": 0,
          "maxIdleTimeClosed": 0,
          "maxLifetimeClosed": 0
        }
      }
    }
  }
}