Choose an Azure compute service

Azure provides many ways to host your application code. The term compute refers to the hosting model for the resources that your application runs on. This article helps you choose a compute service for your application.

Architecture

Use the following flowchart to select a candidate compute service.

Download a Visio file of this architecture.

The previous diagram refers to two migration strategies:

• Lift and shift: A strategy for migrating a workload to the cloud without redesigning the application or making code changes. It's also known as rehosting. For more information, see Azure cloud migration and modernization center.

• Cloud optimized: A strategy for migrating to the cloud by refactoring an application to take advantage of cloud-native features and capabilities.

The output from this flowchart is your starting point. Next, evaluate the service to see if it meets your needs.

This article includes several tables that can help you choose a service. The initial candidate from the flowchart might be unsuitable for your application or workload. In that case, expand your analysis to include other compute services.

If your application consists of multiple workloads, evaluate each workload separately. A complete solution can incorporate two or more compute services.

Understand the basic features

If you're not familiar with the Azure service that you select in the previous section, see the following overview documentation:

• Azure App Service is a managed service for hosting web apps, mobile app back ends, RESTful APIs, or automated business processes.

• Azure Batch is a managed service for running large-scale parallel and high-performance computing (HPC) applications.

• Azure Container Apps is a managed service built on Kubernetes, which simplifies the deployment of containerized applications in a serverless environment.

• Azure Container Instances is a service for running a single container or group of containers in Azure. Container Instances doesn't provide full container orchestration, but you can implement containers without having to provision virtual machines (VMs) or adopt a higher-level service.

• Azure Functions is a service that provides managed functions that run based on a variety of trigger types for event-driven applications.

• Azure Kubernetes Service (AKS) is a managed Kubernetes service for running containerized applications.

• Azure Red Hat OpenShift is a fully managed OpenShift cluster for running containers in production with Kubernetes.

• Azure Service Fabric is a distributed systems platform that can run in many environments, including Azure or on-premises.

• Azure VMware Solution is a managed service for running VMware workloads natively on Azure.

• Azure Virtual Machines is a service where you deploy and manage VMs inside an Azure virtual network.

Understand the hosting models

For hosting models, cloud services fall into three categories:

• Infrastructure as a service (IaaS) lets you provision VMs along with the associated networking and storage components. Then you can deploy any software and applications on those VMs. This model is the closest to a traditional on-premises environment. Microsoft manages the infrastructure, and you manage the VMs.

• Platform as a service (PaaS) provides a managed hosting environment where you can deploy your application without needing to manage VMs or networking resources. App Service and Container Apps are PaaS services.

• Functions as a service (FaaS) lets you deploy your code to the service, which automatically runs it. Azure Functions is a FaaS service.

  Note

  Azure Functions is an Azure serverless compute offering. To see how this service compares with other Azure serverless offerings, such as Azure Logic Apps for serverless workflows, see Choose the right integration and automation services in Azure.

There's a spectrum from IaaS to fully managed PaaS. For example, Azure VMs can automatically scale by using virtual machine scale sets. This capability isn't strictly PaaS, but it resembles the management features in PaaS.

There's a trade-off between control and ease of management. IaaS provides the most control, flexibility, and portability. However, you have to provision, configure, and manage the VMs and network components that you create. FaaS services automatically manage nearly all aspects of running an application. PaaS provides partial management while requiring some user configuration.

Notes:

¹ For Azure Functions, the Consumption plan is serverless. For an App Service plan, functions run on the VMs allocated for that plan. Choose the correct service plan for Azure Functions.

² Higher service-level agreement (SLA) that has two or more instances.

³ Recommended for production environments.

⁴ Can scale down to zero after the job completes.

⁵ Three primary nodes and three worker nodes.

⁶ When you use durable functions.

⁷ See Hosts.

Networking

Notes:

¹ Requires App Service Environment or a dedicated compute pricing tier.

² Use App Service Hybrid Connections.

³ Requires an App Service plan or Azure Functions Premium plan.

DevOps

Note:

¹ Options include IIS Express for ASP.NET or node.js (iisnode), PHP web server, Azure Toolkit for IntelliJ, and Azure Toolkit for Eclipse. App Service also supports remote debugging of deployed web apps.

Scalability

Notes:

¹ See Autoscale pods.

² See Automatically scale a cluster to meet application demands on AKS.

³ See Azure subscription and service limits, quotas, and constraints

⁴ See Set scaling rules in Container Apps

⁵ See Scale Azure VMware Solution

⁶ See VMware NSX

Availability

For guided learning on service guarantees, see Azure architecture and service guarantees.

Security

Review and understand the available security controls and visibility for each of the following services:

• AKS
• App Service
• Azure Functions
• Virtual Machines for Linux
• Azure VMware Solution
• Virtual Machines for Windows
• Batch
• Container Apps
• Container Instances
• Service Fabric

Other criteria

Consider limits and cost

Along with the previous comparison tables, do a more detailed evaluation of the following aspects of the candidate service:

• Cost
• Regional availability
• Service limits
• SLAs

Contributors

Microsoft maintains this article. The following contributors wrote this article.

• Ayobami Ayodeji | Senior Program Manager
• Jelle Druyts | Principal Service Engineer
• Martin Gjoshevski | Senior Service Engineer
• Phil Huang | Senior Cloud Solution Architect
• Julie Ng | Senior Service Engineer
• Paolo Salvatori | Principal Service Engineer

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Next step

• Azure compute options

Related resources

• Choose an Azure compute option for microservices
• Technology choices for Azure solutions