03 - Configuration (Flex Consumption)¶

Configure runtime, app settings, and host storage correctly for Flex Consumption so your app deploys cleanly and scales predictably.

Prerequisites¶

What You'll Build¶

You will configure a deployed Flex Consumption app to use identity-based host storage and validate that runtime settings come from functionAppConfig.

flowchart TD
    INET[Internet] -->|HTTPS| FA[Function App\nFlex Consumption FC1\nLinux Python 3.11]

    subgraph VNET["VNet 10.0.0.0/16"]
        subgraph INT_SUB["Integration Subnet 10.0.1.0/24\nDelegation: Microsoft.App/environments"]
            FA
        end
        subgraph PE_SUB["Private Endpoint Subnet 10.0.2.0/24"]
            PE_BLOB[PE: blob]
            PE_QUEUE[PE: queue]
            PE_TABLE[PE: table]
            PE_FILE[PE: file]
        end
    end

    PE_BLOB --> ST["Storage Account\nallowPublicAccess: false\nallowSharedKeyAccess: false"]
    PE_QUEUE --> ST
    PE_TABLE --> ST
    PE_FILE --> ST

    subgraph DNS[Private DNS Zones]
        DNS_BLOB[privatelink.blob.core.windows.net]
        DNS_QUEUE[privatelink.queue.core.windows.net]
        DNS_TABLE[privatelink.table.core.windows.net]
        DNS_FILE[privatelink.file.core.windows.net]
    end

    PE_BLOB -.-> DNS_BLOB
    PE_QUEUE -.-> DNS_QUEUE
    PE_TABLE -.-> DNS_TABLE
    PE_FILE -.-> DNS_FILE

    FA -.->|User-Assigned MI| UAMI[Managed Identity]
    UAMI -->|RBAC| ST
    FA --> AI[Application Insights]

    subgraph DEPLOY[Deployment]
        BLOB_CTR[Blob Container\ndeployment-packages]
    end
    ST --- BLOB_CTR

    style FA fill:#107c10,color:#fff
    style VNET fill:#E8F5E9,stroke:#4CAF50
    style ST fill:#FFF3E0
    style DNS fill:#E3F2FD

flowchart LR
    Bicep["Bicep/ARM config"] --> App[Function App on FC1]
    App --> Runtime[functionAppConfig.runtime]
    App --> Storage[AzureWebJobsStorage__* settings]
    Storage --> UAMI[User-assigned managed identity]

Steps¶

Step 1: Set Variables¶

export BASE_NAME="flexdemo"
export RG="rg-flexdemo"
export APP_NAME="flexdemo-func"
export PLAN_NAME="flexdemo-plan"
export STORAGE_NAME="flexdemostorage"
export APPINSIGHTS_NAME="flexdemo-insights"
export LOCATION="koreacentral"

Expected output:

Step 2: Configure Identity-Based Host Storage¶

Flex Consumption host storage must be identity-based. Use AzureWebJobsStorage__accountName and related identity keys, not connection strings.

az functionapp config appsettings set \
  --name "$APP_NAME" \
  --resource-group "$RG" \
  --settings \
    "AzureWebJobsStorage__accountName=$STORAGE_NAME" \
    "AzureWebJobsStorage__credential=managedidentity" \
    "AzureWebJobsStorage__clientId=<managed-identity-client-id>" \
  --output json

Expected output:

[
  {
    "name": "AzureWebJobsStorage__accountName",
    "slotSetting": false,
    "value": null
  },
  {
    "name": "AzureWebJobsStorage__credential",
    "slotSetting": false,
    "value": null
  },
  {
    "name": "AzureWebJobsStorage__clientId",
    "slotSetting": false,
    "value": null
  }
]

Step 3: Set Additional App Settings¶

On Flex Consumption, the runtime name and version are defined in functionAppConfig (not in FUNCTIONS_WORKER_RUNTIME). Set only the remaining app-level settings here.

az functionapp config appsettings set \
  --name "$APP_NAME" \
  --resource-group "$RG" \
  --settings \
    "AZURE_FUNCTIONS_ENVIRONMENT=Production" \
  --output json

Expected output:

[
  {
    "name": "AZURE_FUNCTIONS_ENVIRONMENT",
    "slotSetting": false,
    "value": null
  }
]

Step 4: Validate Runtime Configuration Source¶

On Flex, runtime/version and scale settings are defined in functionAppConfig (resource properties), not classic siteConfig.appSettings for runtime identity.

az functionapp show --name "$APP_NAME" --resource-group "$RG" --query "properties.functionAppConfig" --output json

Expected output:

{
  "deployment": {
    "storage": {
      "type": "blobContainer"
    }
  },
  "runtime": {
    "name": "python",
    "version": "3.11"
  },
  "scaleAndConcurrency": {
    "instanceMemoryMB": 2048,
    "maximumInstanceCount": 100
  }
}

Step 5: Confirm Flex Plan Characteristics¶

PLAN_NAME_ACTUAL=$(az functionapp show --name "$APP_NAME" --resource-group "$RG" \
  --query "properties.serverFarmId" --output tsv | awk -F/ '{print $NF}')
echo "Actual plan name: $PLAN_NAME_ACTUAL"

az appservice plan show --name "$PLAN_NAME_ACTUAL" --resource-group "$RG" --query "{sku:sku,reserved:reserved,kind:kind}" --output json

Expected output:

{
  "kind": "functionapp",
  "reserved": null,
  "sku": {
    "name": "FC1",
    "tier": "FlexConsumption"
  }
}

Step 6: Configuration Checklist for Flex¶

• Linux only (reserved: true).
• Host storage uses identity (AzureWebJobsStorage__accountName, __credential, __clientId for UAMI).
• Deployment package source is blob container (functionAppConfig.deployment.storage.type = blobContainer).
• Blob triggers in production must use Event Grid integration.
• No deployment slots.

Verification¶

• az functionapp show --query "properties.functionAppConfig.runtime" returns Python runtime metadata.
• az functionapp config appsettings list includes AzureWebJobsStorage__accountName, AzureWebJobsStorage__credential, and AzureWebJobsStorage__clientId.
• az appservice plan show reports sku.name as FC1 and sku.tier as FlexConsumption.

Next Steps¶

Next: 04 - Logging and Monitoring

See Also¶

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

Sources¶

• App settings reference for Azure Functions
• Flex Consumption how-to
• Identity-based connections for Azure Functions