Virtual Machine Scale Sets

This page describes how Virtual Machine Scale Sets maps to services in the environment where the application runs. Some profiles adapt origin API calls; others translate infrastructure or document target-native behavior.

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Supported environments

API means the profile adapts origin API behavior. Infrastructure means the profile changes provisioned resources or documents a target-native alternative without promising an origin API endpoint. Check the operation and capability tables for the behavior your application depends on.

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How the targets compare

Each row compares a capability of Virtual Machine Scale Sets with its adaptation on each target. A dash means this profile does not state the capability for that target.

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Cloud Adapter

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On AWS

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EC2 Auto Scaling

A scale set becomes an EC2 launch template and Auto Scaling group. The template defines the instance size, image, disks, network interface and identity. Metric rules become scaling policies, and the target provides overprovisioning and load-balancer health checks.

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Capacity changes and update state

The adapter applies the source scale-set configuration to the target group and its launch template. Desired count controls capacity; template settings describe how a new instance boots. An updated template does not establish that existing members have changed, so inspect the group’s rolling-update state before completing the deployment.

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Readiness and replacement

Scaling policies change capacity, while health checks decide when a failed member should be replaced. Check readiness time, batch size, and remaining capacity during updates. A replacement can have a new identity and empty local state; keep durable application data outside disposable fleet members.

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Compatibility differences

Rolling upgrades use instance refresh, which replaces instances instead of reimaging them in place. Publishing a newer image does not automatically update running instances. The build requires acknowledgement if the scale set depends on automatic image upgrades.

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On Google Cloud

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Managed Instance Group

A scale set becomes a Compute Engine instance template and managed instance group. The template defines the VM size, image, disks, network interface and identity.

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Capacity changes and update state

The adapter applies the source scale-set configuration to the target group and its instance template. Desired count controls capacity; template settings describe how a new instance boots. An updated template does not establish that existing members have changed, so inspect the group’s rolling-update state before completing the deployment.

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Readiness and replacement

Scaling policies change capacity, while health checks decide when a failed member should be replaced. Check readiness time, batch size, and remaining capacity during updates. A replacement can have a new identity and empty local state; keep durable application data outside disposable fleet members.

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Compatibility differences

Metric rules become an autoscaler, the health extension becomes an autohealing policy, and rolling upgrades use managed instance group rolling updates. New image versions reach running instances through that update process.

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Existing data and credentials

Selecting a backend does not copy existing data, credentials or access policies. Plan and verify migration separately before changing an application’s endpoint. Do not assume an identifier, credential or encrypted value from the origin service works unchanged on the target.

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Configure, tune and debug

Start with setup and configuration. Use tuning to understand supported request tags, debugging to investigate a request, and High Fidelity Cloud Emulators to validate a bounded reproduction.