az-scout-plugin-aks-placement-advisor 2026.5.0

AKS Placement Advisor plugin for az-scout — evaluates and recommends VM SKUs for AKS node pools

az-scout-plugin-aks-placement-advisor

AKS Placement Advisor plugin for az-scout — evaluates and recommends VM SKUs for AKS node pools with heuristic scoring, AKS eligibility checks, pricing data, and deployment confidence scoring.

Purpose

This plugin helps answer:

• Which VM SKUs are accepted by AKS for node pools in a given region?
• Which SKUs have availability zone support without restrictions?
• Is a SKU eligible for system or user node pools?
• Are quotas sufficient for the selected SKU family?
• What is the estimated cost (pay-as-you-go and spot pricing)?
• What is the deployment confidence level for a SKU in a specific region?
• What fallback SKUs should be considered?

This is a decision-support tool, not a real-time capacity guarantee tool.

How It Works

Data Sources

The plugin combines multiple Azure APIs and enrichment stages to build recommendations:

┌─────────────────────────┐
│  AKS VM SKUs API        │  Primary source — confirms AKS compatibility
│  (ContainerService)     │  aksCompatible = True, vmssSupported = True
└───────────┬─────────────┘
            ▼
┌─────────────────────────┐
│  Compute SKUs API       │  Enrichment — zone restrictions per subscription
│  (Microsoft.Compute)    │  Removes restricted zones, adds warnings
└───────────┬─────────────┘
            ▼
┌─────────────────────────┐
│  Compute Usages API     │  Enrichment — vCPU quota per family
│  (Microsoft.Compute)    │  Shows remaining/used/limit quota, warns if insufficient
└───────────┬─────────────┘
            ▼
┌─────────────────────────┐
│  Pricing API            │  Enrichment — pay-as-you-go and spot prices
│                         │  Adds per-hour cost estimates
└───────────┬─────────────┘
            ▼
┌─────────────────────────┐
│  AKS Eligibility Filter │  System vs user pool eligibility (3-state)
│  (_aks_filter.py)       │  → eligible / warning / ineligible
└───────────┬─────────────┘
            ▼
┌─────────────────────────┐
│  Heuristic Scoring      │  Score 0–100 per SKU (scoring.py)
│                         │  → confidence: high / medium / low
└───────────┬─────────────┘
            ▼
┌─────────────────────────┐
│  Deployment Confidence  │  Weighted score from quota pressure, zone breadth,
│  (az-scout core)        │  restriction density, and price pressure
└─────────────────────────┘

1. AKS VM SKUs API (Microsoft.ContainerService/locations/{location}/vmSkus, 2026-01-02-preview) — returns all VM SKUs accepted by AKS for node pool creation. Every SKU in this list is confirmed AKS-compatible.

2. Compute Resource SKUs API (Microsoft.Compute/skus) — provides per-subscription zone restrictions. A SKU may be listed as available in zones 1, 2, 3 by the AKS API, but restricted in zones 1 and 3 for your specific subscription. The plugin merges these restrictions and removes unavailable zones.

3. Compute Usages API (Microsoft.Compute/locations/{location}/usages) — provides remaining, used, and limit vCPU quota per SKU family.

4. Pricing enrichment — adds pay-as-you-go and spot pricing per SKU.

5. Deployment Confidence (from az-scout core) — a weighted score combining quota pressure, zone breadth, restriction density, and price pressure signals.

Capability Normalisation

The AKS API returns capability names in camelCase (memoryGB, premiumIO) while the Compute API uses PascalCase (MemoryGB, PremiumIO). The plugin normalises all keys to PascalCase internally.

AKS Eligibility Rules

Each SKU is checked for AKS node pool eligibility with a 3-state result: eligible, warning, or ineligible. Rules differ by pool type.

System Node Pools

Ineligible (blocking):

• A-series VMs
• B-series (burstable) VMs
• Promo/Preview SKUs
• < 2 vCPUs or < 4 GB RAM
• No Premium Storage (PremiumIO)
• No availability zones

Warning (non-blocking):

• No Accelerated Networking
• No Ephemeral OS Disk support
• Gen1-only / Trusted Launch unavailable
• No host encryption support
• Zone restrictions in the region

User Node Pools

Ineligible (blocking):

• A-series VMs
• Promo/Preview SKUs
• < 2 vCPUs
• No availability zones

Warning (non-blocking):

• B-series (CPU credit exhaustion risk)
• No Premium Storage
• No Accelerated Networking
• No Ephemeral OS Disk support
• Gen1-only / Trusted Launch unavailable
• No host encryption support
• Not Spot-capable
• ARM64 architecture (image compatibility)
• Low memory (< 4 GB)
• Zone restrictions

Scoring Model

Each SKU receives a heuristic score from 0 to 100, computed as a sum of bonuses and penalties:

Score Components

Factor	Points	Condition
Base score	+40	Every valid AKS VM SKU
Zone support	+20	Has at least 1 availability zone
Multi-zone (≥3 zones)	+15	Available in 3+ zones — critical for HA
VMSS support	+10	Always true for AKS VM SKUs
Rich capabilities	+5	Has ≥4 of: vCPUs, MemoryGB, MaxDataDiskCount, PremiumIO, AcceleratedNetworking, EphemeralOSDisk
Preferred family	+5	SKU name starts with Standard_D, Standard_E, Standard_F, or Standard_B
Quota sufficient	+10	Remaining vCPU quota ≥ SKU vCPU count
Maximum possible	105 → clamped to 100

Penalties

Factor	Points	Condition
Zone restrictions	-25	SKU has zone-level restrictions for your subscription
No zones (when required)	-20	require_zones=true but SKU has no zone support
Unsuitable family	-30	SKU family known to be problematic (e.g. standardLSv2Family)

Confidence Buckets

Score Range	Confidence	Meaning
≥ 75	high	Strong candidate — zones available, no restrictions, quota OK
50 – 74	medium	Usable but with caveats (partial zones, missing quota data)
< 50	low	Significant issues — restrictions, no zones, unsuitable family

Deployment Confidence

In addition to the heuristic score, each SKU receives a deployment confidence score (0–100) from the az-scout core scoring engine. This uses weighted signals:

Signal	Weight	Description
Quota Pressure	38.5%	Non-linear penalty when family vCPU usage exceeds 80%
Zone Breadth	23.1%	Available zones out of 3 (unrestricted)
Restriction Density	23.1%	Fraction of zones without restrictions
Price Pressure	15.4%	Spot-to-PAYGO ratio (lower = better savings potential)

Limitations

• Scores are heuristic estimates. They do not guarantee actual AKS VMSS capacity or VM availability.
• Zone restrictions reflect subscription-level constraints, not real-time capacity. A zone may be unrestricted but temporarily out of stock.
• The AKS VM SKUs API is a preview API (2026-01-02-preview). Behaviour may change.
• Quota data depends on subscription_id being provided. Without it, quota enrichment is skipped.
• Pricing and deployment confidence enrichment are best-effort — failures are logged and the pipeline continues without them.
• No real-time capacity signal. No Azure public API exposes VM stock levels.

Available Routes

All routes are mounted under /plugins/aks-placement-advisor/.

Method	Path	Description
GET	/health	Plugin health status
GET	/regions	Azure regions suitable for Compute SKU lookup
GET	/recommendations	Scored AKS SKU recommendations for a region

GET /recommendations Query Parameters

Parameter	Type	Required	Default	Description
region	string	yes	—	Azure region name (e.g. westeurope)
subscriptionId	string	no	—	Azure subscription ID (required for API calls)
tenantId	string	no	—	Azure tenant ID
require_zones	bool	no	false	Only return SKUs with zone support
require_vmss	bool	no	true	Include VMSS bonus in scoring
min_vcpus	int	no	—	Minimum vCPU count filter
min_memory_gb	float	no	—	Minimum memory in GB filter
sku_name_filter	string	no	—	Substring filter on SKU name
max_results	int	no	0 (all)	Maximum results (0–2000, 0 = no limit)
pool_type	string	no	system	Node pool type: system or user

Response Shape

{
  "region": "westeurope",
  "count": 20,
  "disclaimer": "SKU data comes from the AKS VM SKUs API (preview)...",
  "recommendations": [
    {
      "skuName": "Standard_D4s_v6",
      "region": "westeurope",
      "resourceType": "virtualMachines",
      "family": "standardDSv6Family",
      "size": "D4s_v6",
      "vcpus": 4,
      "memoryGb": 16.0,
      "zones": ["1", "2", "3"],
      "vmssSupported": true,
      "aksCompatible": true,
      "quotaAvailable": 80,
      "quotaLimit": 100,
      "quotaUsed": 20,
      "score": 100.0,
      "confidence": "high",
      "warnings": [],
      "fallbackSkus": ["Standard_D8s_v6", "Standard_D2s_v6"],
      "aks": {
        "status": "eligible",
        "eligible": true,
        "pool_type": "system",
        "errors": [],
        "warnings": []
      },
      "pricing": {
        "paygo": 0.192,
        "spot": 0.038,
        "currency": "USD"
      },
      "deploymentConfidence": {
        "score": 92.0,
        "label": "high",
        "signals": {}
      }
    }
  ]
}

Chat Mode

The plugin registers an AKS Advisor chat mode that provides guided SKU recommendations through conversation. It automatically calls the MCP tools with appropriate filters and presents results as ranked tables with rationale.

Suggested prompts:

• "Find the best SKU for a 3-node system pool"
• "What D-series SKUs are available in westeurope?"
• "Compare westeurope vs northeurope for AKS"
• "Recommend a GPU SKU for ML training"

Available MCP Tools

Tool	Description
recommend_aks_skus	Top AKS-oriented SKU recommendations for a region
compare_aks_regions	Compare multiple regions for AKS SKU placement suitability

recommend_aks_skus

recommend_aks_skus(
    region="westeurope",
    subscription_id="...",
    tenant_id="...",
    require_zones=True,
    min_vcpus=4,
    min_memory_gb=8,
    max_results=10,
)

compare_aks_regions

compare_aks_regions(
    regions=["westeurope", "northeurope", "francecentral"],
    subscription_id="...",
    tenant_id="...",
    min_vcpus=4,
    min_memory_gb=8,
)

Project Structure

src/az_scout_aks_placement_advisor/
├── __init__.py        # Plugin class + module-level `plugin` instance
├── _aks_filter.py     # AKS node pool eligibility rules (system vs user)
├── chat_mode.py       # AKS Advisor chat mode definition
├── models.py          # SkuRecommendation dataclass + DISCLAIMER
├── scoring.py         # Heuristic scoring engine (score_sku, suggest_fallbacks)
├── service.py         # Data pipeline: AKS API → enrichment → scoring
├── routes.py          # FastAPI routes (/health, /regions, /recommendations)
├── tools.py           # MCP tools (recommend_aks_skus, compare_aks_regions)
└── static/
    ├── css/aks-placement-advisor.css
    ├── html/aks-placement-advisor-tab.html
    └── js/aks-placement-advisor-tab.js
tests/
├── test_aks_filter.py
└── test_aks_placement_advisor.py

Installation

# From the az-scout directory
uv pip install -e ../az-scout-plugin-aks-placement-advisor

The plugin is auto-discovered via the az_scout.plugins entry point.

Development

uv pip install -e ".[dev]"

# Quality checks
uv run ruff check src/ tests/
uv run ruff format --check src/ tests/
uv run mypy src/
uv run pytest

Versioning

Version is derived from git tags via hatch-vcs — never hardcoded. Tags follow CalVer: v2026.2.0, v2026.2.1, etc.

License

MIT

Disclaimer

This tool is not affiliated with Microsoft. Scores are heuristic estimates based on publicly available SKU metadata. They do not guarantee actual AKS capacity, availability, or quota. Zone restrictions reflect subscription-level constraints, not real-time stock. Always verify with the Azure portal or CLI before provisioning.