What is the difference between zonal and regional MIGs?

A zonal MIG creates all instances in a single zone, making it simpler but vulnerable to zone failures. A regional MIG distributes instances across multiple zones in a region (up to 3 zones), providing automatic zone-level redundancy. Regional MIGs are recommended for production workloads. The distribution shape setting (even, balanced, any) controls how instances are spread — 'even' distributes equally, 'balanced' favors zones with capacity, and 'any' picks any available zone.

How do rolling updates work in MIGs?

Rolling updates replace instances with a new instance template incrementally. You control the pace with maxSurge (how many extra instances can exist during the update) and maxUnavailable (how many instances can be offline simultaneously). A canary update lets you apply the new template to a subset of instances first. If the canary fails health checks, you can roll back without affecting the remaining instances.

GCP Managed Instance Group Builder

ComputeGCP

Build MIG configurations with autoscaling policies, update strategies, auto-healing, and distribution settings.

Managed Instance Groups Configuration

Build MIG configurations with autoscaling policies, update strategies, auto-healing, and distribution settings.

Required Fields

nameregioninstanceTemplateautoscaler.autoscalingPolicy.minNumReplicasautoscaler.autoscalingPolicy.maxNumReplicas

{
  "name": "prod-web-mig",
  "region": "us-central1",
  "targetSize": 3,
  "instanceTemplate": "projects/my-project/global/instanceTemplates/web-server-template-v2",
  "versions": [
    {
      "instanceTemplate": "projects/my-project/global/instanceTemplates/web-server-template-v2",
      "name": "primary"
    }
  ],
  "updatePolicy": {
    "type": "PROACTIVE",
    "maxSurge": {
      "fixed": 1
    },
    "maxUnavailable": {
      "fixed": 0
    },
    "minimalAction": "REPLACE",
    "mostDisruptiveAllowedAction": "REPLACE",
    "replacementMethod": "SUBSTITUTE",
    "minReadySec": 60
  },
  "autoHealingPolicies": [
    {
      "healthCheck": "projects/my-project/global/healthChecks/web-health-check",
      "initialDelaySec": 300
    }
  ],
  "autoscaler": {
    "name": "prod-web-autoscaler",
    "autoscalingPolicy": {
      "minNumReplicas": 2,
      "maxNumReplicas": 10,
      "coolDownPeriodSec": 60,
      "cpuUtilization": {
        "utilizationTarget": 0.7
      },
      "scaleInControl": {
        "maxScaledInReplicas": {
          "fixed": 1
        },
        "timeWindowSec": 600
      },
      "mode": "ON"
    }
  },
  "namedPorts": [
    {
      "name": "http",
      "port": 8080
    },
    {
      "name": "grpc",
      "port": 9090
    }
  ],
  "distributionPolicy": {
    "targetShape": "EVEN",
    "zones": [
      {"zone": "us-central1-a"},
      {"zone": "us-central1-b"},
      {"zone": "us-central1-c"}
    ]
  }
}

Generated Output

Output will appear here...

About This Tool

Managed Instance Groups (MIGs) are the primary mechanism for running scalable, self-healing groups of identical Compute Engine VMs. MIGs support autoscaling based on CPU, load balancer utilization, or custom metrics, rolling updates with canary deployments, and automatic recreation of failed instances. This builder helps you configure MIG templates, autoscaling policies, update policies, health checks, and distribution shapes (even, balanced, any), outputting gcloud commands or Terraform resources.

When to Use This Tool

•Configuring a regional MIG with autoscaling based on HTTP load balancer request rate for a stateless web application
•Building a MIG with a rolling update policy that replaces 20% of instances at a time with a 3-minute surge window for zero-downtime deployments
•Setting up a MIG with custom metric autoscaling using a Cloud Monitoring metric like queue depth or processing lag
•Creating a stateful MIG that preserves attached persistent disks and static IP addresses across instance recreations

Frequently Asked Questions

What is the difference between zonal and regional MIGs?: A zonal MIG creates all instances in a single zone, making it simpler but vulnerable to zone failures. A regional MIG distributes instances across multiple zones in a region (up to 3 zones), providing automatic zone-level redundancy. Regional MIGs are recommended for production workloads. The distribution shape setting (even, balanced, any) controls how instances are spread — 'even' distributes equally, 'balanced' favors zones with capacity, and 'any' picks any available zone.
How do rolling updates work in MIGs?: Rolling updates replace instances with a new instance template incrementally. You control the pace with maxSurge (how many extra instances can exist during the update) and maxUnavailable (how many instances can be offline simultaneously). A canary update lets you apply the new template to a subset of instances first. If the canary fails health checks, you can roll back without affecting the remaining instances.

Related Learning Guides

Compute Engine Machine Types22 min read

Disclaimer: This tool runs entirely in your browser. No data is sent to our servers. Always verify outputs before using them in production. AWS, Azure, and GCP are trademarks of their respective owners.

GCP Managed Instance Group Builder

ComputeGCP

Build MIG configurations with autoscaling policies, update strategies, auto-healing, and distribution settings.

Managed Instance Groups Configuration

Build MIG configurations with autoscaling policies, update strategies, auto-healing, and distribution settings.

Required Fields

nameregioninstanceTemplateautoscaler.autoscalingPolicy.minNumReplicasautoscaler.autoscalingPolicy.maxNumReplicas

Generated Output

Output will appear here...

About This Tool

When to Use This Tool

•Configuring a regional MIG with autoscaling based on HTTP load balancer request rate for a stateless web application
•Building a MIG with a rolling update policy that replaces 20% of instances at a time with a 3-minute surge window for zero-downtime deployments
•Setting up a MIG with custom metric autoscaling using a Cloud Monitoring metric like queue depth or processing lag
•Creating a stateful MIG that preserves attached persistent disks and static IP addresses across instance recreations

Frequently Asked Questions

What is the difference between zonal and regional MIGs?: A zonal MIG creates all instances in a single zone, making it simpler but vulnerable to zone failures. A regional MIG distributes instances across multiple zones in a region (up to 3 zones), providing automatic zone-level redundancy. Regional MIGs are recommended for production workloads. The distribution shape setting (even, balanced, any) controls how instances are spread — 'even' distributes equally, 'balanced' favors zones with capacity, and 'any' picks any available zone.
How do rolling updates work in MIGs?: Rolling updates replace instances with a new instance template incrementally. You control the pace with maxSurge (how many extra instances can exist during the update) and maxUnavailable (how many instances can be offline simultaneously). A canary update lets you apply the new template to a subset of instances first. If the canary fails health checks, you can roll back without affecting the remaining instances.

Related Learning Guides

Compute Engine Machine Types22 min read