03 - Configuration (Premium)¶

Manage environment settings, runtime options, and host behavior per environment.

Prerequisites¶

• You completed 02 - First Deploy.
• Your function app is running on the Premium plan and responding to HTTP requests.

What You'll Build¶

You will apply required app settings for the Node.js worker and runtime extension, then validate effective settings in Azure. You will also tune host-level timeout behavior appropriate for the Premium plan characteristics.

flowchart LR
    CLI[az CLI] -->|appsettings set| FA[Function App\nPremium EP1]
    FA --> RUNTIME["Runtime Config\n• FUNCTIONS_WORKER_RUNTIME=node\n• FUNCTIONS_EXTENSION_VERSION=~4"]
    FA --> NODE["Node.js Config\n• --max-old-space-size=4096"]
    FA --> HOST["host.json\n• functionTimeout=-1"]

    style FA fill:#ff8c00,color:#fff
    style RUNTIME fill:#E3F2FD
    style NODE fill:#E8F5E9
    style HOST fill:#FFF3E0

Steps¶

Step 1 — Configure app settings¶

az functionapp config appsettings set \
  --name "$APP_NAME" \
  --resource-group "$RG" \
  --settings \
    "FUNCTIONS_WORKER_RUNTIME=node" \
    "FUNCTIONS_EXTENSION_VERSION=~4" \
    "languageWorkers__node__arguments=--max-old-space-size=4096"

Expected output (abridged):

[
  {
    "name": "FUNCTIONS_WORKER_RUNTIME",
    "value": "node"
  },
  {
    "name": "FUNCTIONS_EXTENSION_VERSION",
    "value": "~4"
  },
  {
    "name": "languageWorkers__node__arguments",
    "value": "--max-old-space-size=4096"
  }
]

Step 2 — Configure host timeout¶

Premium supports unlimited function timeout. Set functionTimeout to "-1" in host.json:

{
  "version": "2.0",
  "functionTimeout": "-1"
}

Step 3 — Validate effective config¶

az functionapp config appsettings list \
  --name "$APP_NAME" \
  --resource-group "$RG" \
  --output table

Expected output (key rows):

Name                              Value
--------------------------------  -------------------------
FUNCTIONS_WORKER_RUNTIME          node
FUNCTIONS_EXTENSION_VERSION       ~4
languageWorkers__node__arguments  --max-old-space-size=4096

Step 4 — Verify platform-managed settings¶

Premium automatically creates these settings during provisioning:

az functionapp config appsettings list \
  --name "$APP_NAME" \
  --resource-group "$RG" \
  --query "[?name=='WEBSITE_CONTENTAZUREFILECONNECTIONSTRING' || name=='WEBSITE_CONTENTSHARE' || name=='AzureWebJobsStorage'].{Name:name, Value:'(set)'}" \
  --output table

Expected output:

Name                                      Value
----------------------------------------  -------
AzureWebJobsStorage                       (set)
WEBSITE_CONTENTAZUREFILECONNECTIONSTRING   (set)
WEBSITE_CONTENTSHARE                       (set)

Plan-specific notes¶

• Premium plans require Azure Files content share settings (WEBSITE_CONTENTAZUREFILECONNECTIONSTRING and WEBSITE_CONTENTSHARE) for content storage behavior.
• All app settings can be freely set/updated via az functionapp config appsettings set (unlike Flex Consumption which blocks FUNCTIONS_WORKER_RUNTIME).
• Use an EP plan such as EP1 and configure always-ready capacity for low-latency APIs.
• Use long-form CLI flags for maintainable runbooks.

Verification¶

Name                              Value
--------------------------------  -------------------------
FUNCTIONS_WORKER_RUNTIME          node
FUNCTIONS_EXTENSION_VERSION       ~4
languageWorkers__node__arguments  --max-old-space-size=4096

The table confirms required Node.js worker settings are applied to the deployed app.

See Also¶

• Tutorial Overview & Plan Chooser
• Node.js Language Guide
• Platform: Hosting Plans
• Operations: Deployment
• Recipes Index

Sources¶

• Azure Functions Node.js developer guide (Microsoft Learn)
• Create your first Azure Function with Core Tools (Microsoft Learn)
• Azure Functions hosting options (Microsoft Learn)