How to get metrics from instance group - Health checks

[dewble]

I need to monitor health checks from instance group when I use Loadbalancer.

I think there are 2 cases to monitor but It is inefficient and not that accurate

1. Create and Use Logs-based Metrics from filter "jsonPayload.healthCheckProbeResult.healthState="UNHEALTHY"
   PromQL: stackdriver_global_logging_googleapis_com_log_entry_count
   In this case, I could get only count metrics with no label, I didn't tell which LB have health checks problem

2. Use logs router to pub/sub and monitoring Topic's Message Storeage
   PromQL: stackdriver_pubsub_topic_pubsub_googleapis_com_topic_message_sizes_count
   In this case, If there is unhealth message pub/sub get message and I wathced pub/sub Topic's Message Storeage
   It also has no label about LB, so I have to create logs router for each LB

Is there other method to monitor health checks from instance group or google cloud metrics for stackdriver-exporter ?