Managed Instance Group is attached to a load balancer

Check ID: compute_instance_group_load_balancer_attached
Provider: GCP
Service: compute
Severity: LOW
Categories: resilience
Resource type: compute.googleapis.com/InstanceGroupManager

What this check verifies

Managed Instance Groups (MIGs) should be attached to load balancers via backend services to enable traffic distribution across instances. Load balancers provide health checking, autoscaling integration, and high availability features that are essential for production workloads.

Risk

Without load balancer attachment, MIGs cannot distribute traffic evenly across instances, which impacts:

Application availability - No automatic failover when instances become unhealthy
Scalability - Autoscaling benefits are limited without proper traffic distribution
Performance - Uneven load distribution can cause hotspots and degraded user experience

Recommendation

Attach Managed Instance Groups to load balancers using backend services to enable traffic distribution, health checking, and seamless autoscaling. This ensures high availability and optimal performance for production workloads.

Remediation

CLI
Terraform
Dashboard steps

gcloud compute backend-services add-backend BACKEND_SERVICE_NAME --instance-group=INSTANCE_GROUP_NAME --instance-group-zone=ZONE --global

resource "google_compute_backend_service" "example" {
  name        = "example-backend-service"
  protocol    = "HTTP"
  port_name   = "http"
  timeout_sec = 30

  # Attach MIG as backend
  backend {
    group = google_compute_instance_group_manager.example.instance_group
  }

  health_checks = [google_compute_health_check.example.id]
}

References

Where this check fires

This check runs on every scheduled scan against your GCP account. Findings appear at Cloud Security → Findings filterable by Check ID = compute_instance_group_load_balancer_attached. To re-evaluate after a fix, hit Run now on the account’s schedule under Cloud Security → Schedules — the next scan re-checks this control and marks the finding fixed or keeps it persistent.

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Managed Instance Group has autohealing with a health check Managed Instance Groups span multiple zones

​What this check verifies

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​Recommendation

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What this check verifies

Risk

Recommendation

Remediation

References

Where this check fires