azure-compute

Azure Compute

Choose the compute option with the lowest operational burden that meets your workload's functional and non-functional requirements. Managed services first; IaaS only when control is mandatory.

Use This Skill When

• The user asks which Azure compute service to use (Functions vs. App Service vs. AKS)
• A workload must move from on-premises or another cloud to Azure
• The user needs trade-off analysis: cost, scaling, latency, compliance
• The user needs operational readiness assessment

Context: Compute Maturity Spectrum

Serverless (Least ops):
  Azure Functions
  └─ Pro: Zero infrastructure, auto-scale, pay-per-exec
  └─ Con: Cold starts, max 10-min timeout, limited languages

PaaS (Low ops):
  App Service
  └─ Pro: Built-in scaling, diagnostics, deployment slots
  └─ Con: Single-region, limited customization
  
  Container Apps
  └─ Pro: Container-native, auto-scaling, event-driven
  └─ Con: Smaller ecosystem, newer service

Containers + Orchestration:
  Azure Kubernetes Service (AKS)
  └─ Pro: Full Kubernetes control, multi-region, custom scaling
  └─ Con: Requires Kubernetes expertise, higher operational burden

IaaS (Most control, Most ops):
  Virtual Machines / VMSS
  └─ Pro: OS-level control, custom binaries, legacy support
  └─ Con: Requires manual patching, scaling, monitoring

Required Inputs

• Workload type: Web API, background job, ML training, legacy app, real-time analytics
• Traffic pattern: Constant, bursty, seasonal, event-driven
• Latency requirement: Sub-100ms, <500ms, or flexible
• Availability: 99%, 99.9%, 99.95%?
• Scaling needs: Min/max instances, target response time
• Compliance: On-premises only, specific regions, data residency
• Team skills: DevOps, Kubernetes expertise, vendor lock-in tolerance
• Budget: TCO vs. OpEx preference

Decision Tree

Is this a background job triggered by an event (file upload, message queue, timer)?
├─ Yes → Azure Functions (lowest cost, auto-scale, easy)
│         But if: Job runs >10 min → Container Apps or App Service
└─ No → Continue

Is this a stateless HTTP API or web app?
├─ Yes → App Service (built-in scaling, diagnostics)
│         Or: Container Apps (if containerized, multi-region)
├─ Needs Kubernetes → AKS
└─ No → Continue

Does this need OS-level control (custom packages, specific kernel version)?
├─ Yes → Virtual Machines or VMSS
└─ No → One of above managed options

Is latency critical (< 100ms p99)?
├─ Yes → Consider colocating compute with data store (same region/AZ)
│         Evaluate: App Service Plan, VMSS, or Container Apps with CPU optimization
└─ No → Standard deployment acceptable

Do you need to orchestrate multiple microservices?
├─ Yes → AKS (service mesh, traffic mgmt, multi-region)
│         Or: App Service + API Management (simpler, less overhead)
└─ No → Single-service option (Functions, App Service)