AKS vs App Service vs Functions decision in Azure - CLI Comparison

Introduction

Choosing the right way to run your app on Azure can be confusing. AKS, App Service, and Functions each solve different problems about how your app runs and scales.

Use AKS when you want full control over containers and need to run many apps together with complex networking.

Use App Service when you want to quickly deploy web apps without managing servers or infrastructure.

Use Functions when you want to run small pieces of code that respond to events and scale automatically.

Commands

This command creates an AKS cluster with 2 nodes and monitoring enabled. It sets up the environment to run containerized apps with Kubernetes.

Terminal

az aks create --resource-group example-rg --name example-aks --node-count 2 --enable-addons monitoring --generate-ssh-keys

Expected Output

Waiting for AAD role to propagate

Succeeded

{

  "agentPoolProfiles": [

    {

      "count": 2,

      "maxPods": 110,

      "name": "nodepool1",

      "osType": "Linux",

      "vmSize": "Standard_DS2_v2"

    }

  ],

  "fqdn": "example-aks-12345.hcp.eastus.azmk8s.io",

  "kubernetesVersion": "1.26.3",

  "location": "eastus",

  "name": "example-aks",

  "resourceGroup": "example-rg",

  "type": "Microsoft.ContainerService/ManagedClusters"

}

→

--node-count - Sets how many nodes the cluster will have

→

--enable-addons - Adds extra features like monitoring

This command creates an App Service web app using a specified plan and runtime. It lets you deploy web apps without managing servers.

Terminal

az webapp create --resource-group example-rg --plan example-plan --name example-app --runtime "DOTNET|7.0"

Expected Output

{

  "id": "/subscriptions/xxxx/resourceGroups/example-rg/providers/Microsoft.Web/sites/example-app",

  "name": "example-app",

  "state": "Running",

  "type": "Microsoft.Web/sites"

}

→

--plan - Specifies the App Service plan that defines the compute resources

→

--runtime - Sets the language and version your app uses

This command creates a serverless Function App that runs Python code. It uses a consumption plan that scales automatically based on demand.

Terminal

az functionapp create --resource-group example-rg --consumption-plan-location eastus --runtime python --functions-version 4 --name example-func --storage-account examplestorage

Expected Output

{

  "id": "/subscriptions/xxxx/resourceGroups/example-rg/providers/Microsoft.Web/sites/example-func",

  "name": "example-func",

  "state": "Running",

  "type": "Microsoft.Web/sites"

}

→

--consumption-plan-location - Sets the region and plan type for serverless scaling

→

--runtime - Specifies the language runtime for the function

This command downloads the credentials to connect to the AKS cluster so you can manage it with kubectl.

Terminal

az aks get-credentials --resource-group example-rg --name example-aks

Expected Output

Merged "example-aks" as current context in /home/user/.kube/config

This command lists the nodes in your AKS cluster to verify it is running and ready.

Terminal

kubectl get nodes

Expected Output

NAME                                STATUS   ROLES   AGE   VERSION

aks-nodepool1-12345678-vmss000000   Ready    agent   5m    v1.26.3

Key Concept

If you remember nothing else from this pattern, remember: AKS is for container control, App Service is for easy web apps, and Functions are for event-driven code.

Common Mistakes

Trying to use Functions for long-running apps

Functions are designed for short, event-driven tasks and may time out or cost more if used for long processes

Use App Service or AKS for apps that run continuously or need complex logic

Deploying complex multi-container apps directly to App Service without containers

App Service supports containers but is limited for complex orchestration and scaling compared to AKS

Use AKS for multi-container or microservices apps needing advanced networking

Not setting up monitoring when creating AKS

Without monitoring, you can't easily see cluster health or logs, making troubleshooting hard

Always enable monitoring addon during AKS creation

Summary

Create AKS for full container orchestration with control over nodes and scaling.

Use App Service to quickly deploy and manage web apps without infrastructure management.

Choose Functions for small, event-triggered code that scales automatically.