Sku Quota Validation

Quota Validation Procedure

⛔ Use az rest, NOT az quota list. The az quota list CLI extension triggers a full extension metadata scan on startup. If ANY installed extension has a permission error (common: azure-devops WinError 5 on Windows), the entire command fails. az rest is a built-in command that bypasses extension loading entirely and hits the same REST API. Quota increases are free — you only pay for resources actually used.

⛔ what-if does NOT catch App Service quota errors. az deployment sub what-if returns Succeeded even when the target SKU has limit=0. The quota rejection only surfaces at actual az deployment sub create time. This means the prepare-phase quota check is the ONLY pre-deploy safety net — do not skip or shortcut it.

⛔ Do NOT use az vm list-usage, az appservice list-locations, or mcp_azure_mcp_quota for quota checks. They return misleading data — see Anti-Patterns below.

Region Selection

Build the scan list dynamically — do NOT hardcode a fixed set of regions:

1. User’s preferred region — read context.json.azure.region or context.json.overrides[] for a region preference. If stated, scan that region first.
2. Nearest alternates — add 3–4 regions geographically close to the user’s preferred region from the global pool below.
3. If no user preference — default to a well-supported region (e.g., eastus2) and scan 4 alternates from the user’s likely geography (infer from subscription tenant location or ask).

Global region pool: eastus2, eastus, westus2, centralus, westeurope, northeurope, australiaeast, japaneast, southeastasia, brazilsouth

Agent: adapt shell syntax to detected environment. PowerShell shown below; use equivalent syntax on bash/zsh (e.g., for region in eastus eastus2 ...; do ... done).

⛔ PowerShell ? in URLs: When building az rest URLs with variable interpolation, PowerShell may strip ? from ?api-version=. Always use the URL inline in double quotes (as shown below), NOT via a $url variable. If you must use a variable, wrap the ? with a backtick: `?api-version=.

Per-Provider Scripts

Use az rest for all quota checks. Query BOTH limit AND usage (limit alone is insufficient).

App Service: Query quota + usages endpoints per region:

Container Apps: /usages gives usage+limit in one call:

Static Web Apps: No Microsoft.Quota provider — Free plan caps at ~10 apps/subscription (per docs; may vary, treat as guideline). Count existing Free apps:

At/near cap → treat SWA Free as UNAVAILABLE (no self-service increase — raises need a support request). Fall back per After Checking.

Storage — default limit 250 accounts/region. Rarely exhausted — skip programmatic check unless the plan requires multiple storage accounts.

Key Vault — no quota API exists (returns NotFound). Default limit ~1000 vaults/subscription. Skip programmatic check.

Interpret Results

• available > 0 → AVAILABLE. available = 0 / limit <= 0 → BLOCKED (a limit=0, used=-1 response is the API sentinel for “Free tier not offered in this region” — the script clamps it so it does not read as available). 404/empty → fallback candidate.
• az rest fails → quotaValidation: { verified: false, method: "unverifiable" }.

After Checking

1. Only offer regions with confirmed capacity — “try anyway” on zero/unconfirmed quota is a known deploy failure. 1b. Free tier missing in requested region but present elsewhere → present BOTH, ranked by cost: (a) free tier in nearest confirmed region ($0, recommended), (b) cheapest tier IN the requested region (show monthly cost + assumptions[] note). User picks — never silently relocate (region may be a data-residency/latency requirement).
2. Free SKU zero in ALL regions → step down the fallback ladder to the cheapest available option (don’t jump to a named tier — let live quota decide):
   • Static-capable app → SWA Free, but only if its cap isn’t reached (see Static Web Apps above).
   • No free option left → cheapest available paid tier the app supports. This breaks the “free” promise — add an assumptions[] note stating why (e.g., “No F1 quota in {checkedRegions} and SWA Free cap reached”).
   • All tiers exhausted → HALT: specify region, switch compute type, request increase at portal, or cancel.
3. Write prepare-plan.json.quotaValidation: { verified: true, method: "cli", verifiedRegion, verifiedSku, checkedRegions[], failedResources[] }.

Offer Restriction Check (Database Services)

⛔ what-if/validate do NOT catch LocationIsOfferRestricted. Use capabilities API.

For MySQL: change $provider = 'Microsoft.DBforMySQL' and $apiVer = '2023-12-30'.

⛔ JMESPath MUST start with value[0].. URL MUST include /locations/{region}/. Empty/null response = BLOCKED. Write results to quotaValidation.offerRestrictions[].

⛔ Select the engine version deterministically from the capabilities payload — match the app’s detected version, upgrading only to the nearest compatible release. The payload lists supported versions at value[0].supportedFlexibleServerEditions[0].supportedServerVersions[].name (e.g. MySQL: 5.7, 8.0.21, 8.4, 9.5). Using the detected DB version passed by the caller (from context.json.detectedServices[]):

1. If the exact detected version (or its exact patch) is in the supported list → use it.
2. Else use the lowest supported version whose major ≥ the detected major (detected 5.7, supported [5.7, 8.0.21, 8.4, 9.5] → 8.0.21). Picking the lowest compatible major — not the newest — avoids the 60+ minute provisioning hangs seen on brand-new majors (e.g. 9.x) and keeps compatibility with the app’s driver/ORM. Return it in the quota output’s per-service version field; the orchestrator copies it to prepare-plan.json.services[].version at plan-write (exact patch required — see prepare-schemas.ts version). Record the bump in assumptions[] if the detected version was upgraded.

Anti-Patterns

⛔ az quota list (extension failures), az vm list-usage (wrong layer), az appservice list-locations (ignores quota), mcp_azure_mcp_quota (misleading), what-if/validate (false positives).

Deploy Gate Re-Validation

If quotaValidation.verified == false at deploy gate: re-run Per-Provider Scripts above. Pass → update quotaValidation. Fail → present alternatives. az rest fails → warn and proceed.

Sub-Agent Delegation

When delegating from prepare Step 5, provide: subscriptionId, SKU list from prepare-plan.json.services[].sku, preferred region + fallbacks, list of managed database services, and this file’s content. See subagent-quota.md for the template.