Azure offers compute from full VMs down to functions that run only when triggered. Pick by how much you want to manage.

Services: Virtual Machines, VM Scale Sets, App Service, Container Instances, Container Registry (ACR), Kubernetes Service (AKS), Container Apps, Functions, Logic Apps, Batch, Virtual Desktop.

Virtual Machines

You choose OS, size, disks and network. You pay for compute while the VM is allocated; disks cost even when it is stopped.

$ az vm create \
    --resource-group rg-demo --name vm-web \
    --image Ubuntu2204 --size Standard_B2s \
    --admin-username azureuser --generate-ssh-keys
$ az vm list -o table
$ az vm deallocate -g rg-demo -n vm-web     # stops compute billing
$ az vm start -g rg-demo -n vm-web

VM sizes (families)

• B: burstable, cheap, dev/test
• D: general purpose
• E: memory optimised
• F: compute optimised
• N: GPU
• L: storage optimised

Stopped vs deallocated

• Stopped from inside the OS: still allocated, still billed
• Deallocated via Azure: compute released, no compute charge

Resilience for VMs

• Availability zones: spread across datacenters in a region
• Availability sets: spread across fault/update domains in one datacenter
• Scale Sets: auto add/remove instances based on metrics or schedule
• Reserved Instances / Savings Plans: 1 or 3 year commitment for large discounts
• Spot VMs: spare capacity at deep discount, can be evicted

Azure App Service

PaaS for web apps, REST APIs and mobile back ends. Supports .NET, Java, Node.js, Python, PHP and containers.

• Runs inside an App Service plan that defines region, OS, size and scale
• Deployment slots (staging, production) with swap for zero-downtime deploys
• Built-in autoscale, custom domains, TLS, authentication, CI/CD from GitHub / Azure DevOps

$ az appservice plan create -g rg-demo -n plan-web --sku B1 --is-linux
$ az webapp create -g rg-demo -p plan-web -n my-unique-webapp --runtime "NODE:20-lts"
$ az webapp deployment slot create -g rg-demo -n my-unique-webapp --slot staging

Containers

Azure Container Instances (ACI)

Run a container with no VM to manage. Billed per second. Good for short tasks and bursts.

$ az container create -g rg-demo -n aci-demo --image nginx --dns-name-label my-aci --ports 80

Azure Container Registry (ACR)

Private registry for images (like Docker Hub, but yours).

$ az acr create -g rg-demo -n myregistry123 --sku Basic
$ az acr build -r myregistry123 -t myapp:v1 .

Azure Kubernetes Service (AKS)

Azure runs the control plane for free; you pay for the node pools. See 2. Kubernetes Architecture – from Container Images to Running Pods.

$ az aks create -g rg-demo -n aks-demo --node-count 2 --generate-ssh-keys
$ az aks get-credentials -g rg-demo -n aks-demo

Azure Container Apps

Serverless containers built on Kubernetes, with scale to zero and event-driven scaling (KEDA). No cluster to run.

Azure Functions

Event-driven serverless code. Execution is started by a trigger and can read/write data through bindings.

Hosting plans

import azure.functions as func

app = func.FunctionApp()

@app.route(route="hello", auth_level=func.AuthLevel.FUNCTION)
def hello(req: func.HttpRequest) -> func.HttpResponse:
    name = req.params.get("name", "world")
    return func.HttpResponse(f"Hello, {name}")

Durable Functions

Extension for stateful workflows in code: function chaining, fan-out/fan-in, human approval, long-running monitors.

Choosing Compute

• Lift-and-shift legacy app → VM
• Standard web app / API → App Service
• Microservices needing orchestration → AKS or Container Apps
• Run a quick container job → ACI
• React to events with small code → Functions