How does OCI instance pool autoscaling work?

Autoscaling policies monitor metrics (CPU utilization, memory, custom metrics) and automatically adjust the pool size between configured minimum and maximum instance counts. Threshold-based policies scale out when a metric exceeds an upper threshold and scale in when it drops below a lower threshold. Scheduled policies adjust pool size at specific times (e.g., scale to 10 instances at 8 AM, scale to 3 at 8 PM). Cooldown periods prevent rapid scaling oscillation.

What happens when an instance in the pool becomes unhealthy?

Instance pools automatically detect and replace unhealthy instances. When an instance is terminated, crashes, or fails a health check from the attached load balancer, the pool launches a replacement instance using the same instance configuration. The new instance is placed in the same availability domain and is automatically registered with any attached load balancer backend sets. This self-healing behavior maintains your desired capacity without manual intervention.

OCI Instance Pool Config Builder

ComputeOCI

Build instance pool and placement configurations with availability domain distribution.

OCI Compute Instance Pools Configuration

Build instance pool and placement configurations with availability domain distribution.

Required Fields

compartmentIddisplayNameinstanceConfigurationIdsizeplacementConfigurations

{
  "compartmentId": "ocid1.compartment.oc1..aaaaaaaexample",
  "displayName": "web-tier-instance-pool",
  "instanceConfigurationId": "ocid1.instanceconfiguration.oc1.iad.aaaaaaaexample",
  "size": 3,
  "placementConfigurations": [
    {
      "availabilityDomain": "Uocm:US-ASHBURN-AD-1",
      "primarySubnetId": "ocid1.subnet.oc1.iad.aaaaaaasubnet1",
      "faultDomains": ["FAULT-DOMAIN-1", "FAULT-DOMAIN-2"],
      "primaryVnicSubnets": {
        "subnetId": "ocid1.subnet.oc1.iad.aaaaaaasubnet1",
        "isAssignIpv6Ip": false
      },
      "secondaryVnicSubnets": []
    },
    {
      "availabilityDomain": "Uocm:US-ASHBURN-AD-2",
      "primarySubnetId": "ocid1.subnet.oc1.iad.aaaaaaasubnet2",
      "faultDomains": ["FAULT-DOMAIN-1", "FAULT-DOMAIN-3"],
      "primaryVnicSubnets": {
        "subnetId": "ocid1.subnet.oc1.iad.aaaaaaasubnet2",
        "isAssignIpv6Ip": false
      },
      "secondaryVnicSubnets": []
    }
  ],
  "loadBalancers": [
    {
      "loadBalancerId": "ocid1.loadbalancer.oc1.iad.aaaaaaaexample",
      "backendSetName": "web-backend-set",
      "port": 443,
      "vnicSelection": "PrimaryVnic"
    }
  ],
  "instanceConfiguration": {
    "shape": "VM.Standard.E4.Flex",
    "shapeConfig": {
      "ocpus": 2,
      "memoryInGBs": 16
    },
    "sourceDetails": {
      "sourceType": "image",
      "imageId": "ocid1.image.oc1.iad.aaaaaaaexample",
      "bootVolumeSizeInGBs": 100
    }
  },
  "freeformTags": {
    "tier": "web",
    "environment": "production"
  }
}

Generated Output

Output will appear here...

About This Tool

OCI Instance Pools let you create and manage groups of identical Compute instances as a single entity, with support for autoscaling, automatic instance replacement, and integration with load balancers. Instance pools use instance configurations (templates) to define the shape, image, networking, and metadata for instances. This builder helps you configure instance pools with placement constraints, fault domain distribution, autoscaling policies, and load balancer backend set attachments.

When to Use This Tool

•Creating an instance pool with autoscaling based on CPU utilization for a web application tier behind an OCI Load Balancer
•Configuring a pool that distributes instances evenly across fault domains within an availability domain for high availability
•Building an instance pool with scheduled scaling policies that increase capacity during business hours and reduce it overnight
•Setting up an instance pool with custom metric-based autoscaling using OCI Monitoring metrics from your application

Frequently Asked Questions

How does OCI instance pool autoscaling work?: Autoscaling policies monitor metrics (CPU utilization, memory, custom metrics) and automatically adjust the pool size between configured minimum and maximum instance counts. Threshold-based policies scale out when a metric exceeds an upper threshold and scale in when it drops below a lower threshold. Scheduled policies adjust pool size at specific times (e.g., scale to 10 instances at 8 AM, scale to 3 at 8 PM). Cooldown periods prevent rapid scaling oscillation.
What happens when an instance in the pool becomes unhealthy?: Instance pools automatically detect and replace unhealthy instances. When an instance is terminated, crashes, or fails a health check from the attached load balancer, the pool launches a replacement instance using the same instance configuration. The new instance is placed in the same availability domain and is automatically registered with any attached load balancer backend sets. This self-healing behavior maintains your desired capacity without manual intervention.

Related Learning Guides

OCI Compute Shapes & Instances18 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.

OCI Instance Pool Config Builder

ComputeOCI

Build instance pool and placement configurations with availability domain distribution.

OCI Compute Instance Pools Configuration

Build instance pool and placement configurations with availability domain distribution.

Required Fields

compartmentIddisplayNameinstanceConfigurationIdsizeplacementConfigurations

Generated Output

Output will appear here...

About This Tool

When to Use This Tool

•Creating an instance pool with autoscaling based on CPU utilization for a web application tier behind an OCI Load Balancer
•Configuring a pool that distributes instances evenly across fault domains within an availability domain for high availability
•Building an instance pool with scheduled scaling policies that increase capacity during business hours and reduce it overnight
•Setting up an instance pool with custom metric-based autoscaling using OCI Monitoring metrics from your application

Frequently Asked Questions

How does OCI instance pool autoscaling work?: Autoscaling policies monitor metrics (CPU utilization, memory, custom metrics) and automatically adjust the pool size between configured minimum and maximum instance counts. Threshold-based policies scale out when a metric exceeds an upper threshold and scale in when it drops below a lower threshold. Scheduled policies adjust pool size at specific times (e.g., scale to 10 instances at 8 AM, scale to 3 at 8 PM). Cooldown periods prevent rapid scaling oscillation.
What happens when an instance in the pool becomes unhealthy?: Instance pools automatically detect and replace unhealthy instances. When an instance is terminated, crashes, or fails a health check from the attached load balancer, the pool launches a replacement instance using the same instance configuration. The new instance is placed in the same availability domain and is automatically registered with any attached load balancer backend sets. This self-healing behavior maintains your desired capacity without manual intervention.

Related Learning Guides

OCI Compute Shapes & Instances18 min read