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Frequently Asked Questions (FAQs)

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Chandni Patel edited this page Aug 23, 2023 · 12 revisions

Why ZipDeploy resource fails in the ARM Template?


  1. Missing dependsOn

Please make sure you declare that the ZipDeploy resource depends on the site. Dependencies are required for resources that are deployed within the same template, especially when the order of creation matters. For Example: If function app site and ZipDeploy extension are being deployed in the same template, then it is important to declare that the ZipDeploy resource depends on the site. Because only after the creation of the site, we want to create ZipDeploy extension for deployment.

Solution: The following example shows declartion of dependsOn element, and for the full deployment template, see Function App with Basic Resources template:

"dependsOn": [
  "[concat('Microsoft.Web/sites/', parameters('siteName'))]"
],

  1. Updating AppSettings in the same Template

Please make sure that the app settings are NOT being independently updated in the same ARM template as the deployment. For Example: The following template can fail the deployment, because on updating the app settings in the ARM template, the existing app settings will be deleted, and then new app settings will be created using the ARM template. During this process, the new app settings are not yet available. If the ZipDeploy starts in parallel being in the same template, then the app setting might not be available this time and the deployment can fail.

"resources": [
  {
    "apiVersion": "2018-11-01",
    "name": "[concat(parameters('functionAppName'), '/appsettings')]",
    "type": "Microsoft.Web/sites/config",
    "dependsOn": [
      "[resourceId('Microsoft.Web/sites', parameters('functionAppName'))]",
      "[resourceId('Microsoft.Storage/storageAccounts', variables('storageAccountName'))]"
    ],
    "properties": {
      "AzureWebJobsStorage": "[concat('DefaultEndpointsProtocol=https;AccountName=', variables('storageAccountName'), ';EndpointSuffix=', environment().suffixes.storage, ';AccountKey=',listKeys(resourceId('Microsoft.Storage/storageAccounts', variables('storageAccountName')), '2019-06-01').keys[0].value)]",
      "APPINSIGHTS_INSTRUMENTATIONKEY": "[reference(resourceId('microsoft.insights/components', variables('applicationInsightsName')), '2020-02-02-preview').InstrumentationKey]",
      "FUNCTIONS_EXTENSION_VERSION": "~3",
      "WEBSITE_RUN_FROM_PACKAGE": "1"
    }
  },
  {
    "name": "[concat(parameters('functionAppName'), '/ZipDeploy')]",
    "type": "Microsoft.Web/sites/extensions",
    "apiVersion": "2021-02-01",
    "location": "[parameters('location')]",
    "dependsOn": [
      "[resourceId('Microsoft.Web/sites', parameters('functionAppName'))]"
    ],
    "properties": {
      "packageUri": "[parameters('packageUri')]"
    }
  }
]

Solution: Try to deploy with one of the two ways mentioned below.
i) It is strictly recommended to include AppSettings as part of Site resource, instead of providing it separately in resources like SiteConfig resource, Sites/Config and Sites/AppSettings resources. When creating the site, add app settings to site config under properties like this "properties": { "siteConfig": { "appSettings": [ ] } } } and make the ZipDeploy resource depend on the site. Here is the sample template.
ii) You can split it into two separate ARM templates. First, run the template to update the app settings, and then second template for deployment.

  1. Invalid or Expired SAS URL

One of the common reasons for the following error is that the specified SAS URL was invalid or has expired. So, failed to download zip from URL.

Error Detail: The resource operation completed with terminal provisioning state 'Failed'. (Code: ResourceDeploymentFailure) Raw Error:

{
  "code": "DeploymentFailed",
  "message": "At least one resource deployment operation failed. Please list deployment operations for details. Please see https://aka.ms/DeployOperations for usage details.",
  "details": [
    {
      "code": "Conflict",
      "message": "{\r\n  \"status\": \"Failed\",\r\n  \"error\": {\r\n    \"code\": \"ResourceDeploymentFailure\",\r\n    \"message\": \"The resource operation completed with terminal provisioning state 'Failed'.\"\r\n  }\r\n}"
    }
  ]
}

Solution: Please check the specified SAS URL is valid. You can navigate to Kudu debug console and curl on the URL to verify if Zip download works. If the URL is invalid or has expired, then regenerate the URL.

  1. Linux Consumption plan

ZipDeploy extension and the appSetting WEBSITE_RUN_FROM_PACKAGE=1 are not supported for Linux Consumption plan.

Solution: If you are using Linux Consumption plan, then:

  • Do not use ZipDeploy extension.
  • Set appSetting WEBSITE_RUN_FROM_PACKAGE=URL for deployment using the .zip package url. For example:

NOTE: Please include rest of the existing app settings in the template to preserve them.

{
  "name": "[parameters('siteName')]",
  "type": "Microsoft.Web/sites",
  "apiVersion": "2021-02-01",
  "location": "[parameters('location')]",
  "properties": {
    "siteConfig": {
      "appSettings": [
        {
          "name": "WEBSITE_RUN_FROM_PACKAGE",
          "value": "[parameters('packageUri')]"
        }
      ]
    }
  }
}

When is the dependsOn required?

Dependencies are required for resources that are deployed within the same template, especially when the order of creation matters. For Example: If function app site and ZipDeploy extension are being deployed in the same template, then it is important to declare that the ZipDeploy resource depends on the site. Because only after the creation of the site, we want to create ZipDeploy extension for deployment. Here is more information on dependsOn.


Can we use the appSetting WEBSITE_RUN_FROM_PACKAGE=1 with MSDeploy?

  • No. The appSetting WEBSITE_RUN_FROM_PACKAGE=1 is only available with ZipDeploy, not MSDeploy.
  • The ZipDeploy extension with the appSetting WEBSITE_RUN_FROM_PACKAGE=1 is the recommended path of deployment, except for Linux Consumption plan.
  • For Linux Comsumption plan, please remove MSDeploy extension and remove ZipDeploy extension. Then add the app setting WEBSITE_RUN_FROM_PACKAGE = packageURL for deployment in ARM Template.

Why MSDeploy extension is not working with Linux?

  • MSDeploy is not supported with Linux, it is Windows only. MSDeploy is not a recommended deployment mechanism for Azure Functions.
  • For Premium and Dedicated plan on Linux, use ZipDeploy extension and set the appSetting WEBSITE_RUN_FROM_PACKAGE=1.
  • For Linux Comsumption plan, please remove MSDeploy extension and remove ZipDeploy extension. Then add the app setting WEBSITE_RUN_FROM_PACKAGE = packageURL for deployment in ARM Template.

Why ZipDeploy extension is not working with Linux Consumption plan?

OR Why WEBSITE_RUN_FROM_PACKAGE=1 is not working for function app with Consumption plan on Linux?

  • ZipDeploy extension and the appSetting WEBSITE_RUN_FROM_PACKAGE=1 is not supported with Linux Consumption plan. It is the recommended deployment path for all other OS and SKU.
  • For Linux Comsumption plan, please add the app setting WEBSITE_RUN_FROM_PACKAGE = packageURL for deployment in ARM Template.

Why remote build is not working on Linux after setting SCM_DO_BUILD_DURING_DEPLOYMENT=true?

To enable the remote build processes on Linux, please verify the following app settings (you can simply verify configurations on the Azure portal):

  • WEBSITE_RUN_FROM_PACKAGE=0 or WEBSITE_RUN_FROM_PACKAGE app setting removed
  • SCM_DO_BUILD_DURING_DEPLOYMENT=true

For Functions app on Linux, ENABLE_ORYX_BUILD=true is set by default. If this build does not work for you e.g. for dotnet or java app, then set ENABLE_ORYX_BUILD=false.


Why DevOps task and ARM template deployment was successful but latest code not reflected on site?

WEBSITE_RUN_FROM_PACKAGE setting should be made consistent between ARM template and Deployment task to avoid unexpected issues around file updates when deploying. For example, if using "Run From Package" in the DevOps deployment task, make sure the ARM template also uses WEBSITE_RUN_FROM_PACKAGE = 1, and if not using "Run From Package" in the DevOps deployment task, make sure the ARM template uses WEBSITE_RUN_FROM_PACKAGE = 0.

When setup DevOps pipeline with RunFromPackage option, for every run, DevOps will automatically add WEBSITE_RUN_FROM_PACKAGE=1 to the current AppSettings collection. As part of the pipeline, user often provides script/template to create/update the site and its AppSettings. If user misses to include this as well, it creates a situation as if the setting is removed and re-added back for every run. This leads to file system being changed during deployment and a common source of transient issue if not missing deployed content altogether. Therefore, make sure the template or script include WEBSITE_RUN_FROM_PACKAGE=1 if DevOps's RunFromPackage is selected and vice versa.


Why function app is NOT starting?

Changing or removing these settings may cause your function app to not start. Please make sure you have these required settings.

App setting required for all OS and SKU:

  • AzureWebJobsStorage

App setting required for Premium plan or Consumption plan on Windows and Premium plan on Linux:

  • WEBSITE_CONTENTAZUREFILECONNECTIONSTRING
  • WEBSITE_CONTENTSHARE

NOTE: In ARM template, for Windows, do not need to set the WEBSITE_CONTENTSHARE setting in a deployment slot, because it is generated for you when the app is created in the deployment slot.

NOTE: In ARM template, for Windows, do not need to set the WEBSITE_CONTENTSHARE setting for Elastic Premium plan, because it is generated for you when the site is first created.


Why is the function app restarting during Deployment Slot Swap?

OR Why the Function app is unavailable (throwing 500 error) during slot swap for a few seconds?

  • Set WEBSITE_SKIP_ALL_BINDINGS_IN_APPHOST_CONFIG to 1 to skip all bindings in applicationHost.config. If your app triggers a restart because applicationHost.config is updated with the swapped hostnames of the slots, set this variable to true to avoid a restart of this kind. It is set to avoid restart during deployment slot swap if there was a restart due to the addition of the bindings.
  • If you are running a Windows Communication Foundation (WCF) app, do not set this variable.

How to swap deployment slot with production slot using ARM template?

For swapping the 2 slots, it is recommended to have 2 separate templates:

  1. First run this template successfully for deploying to slot using ZipDeploy. Test deployment slot thoroughly if any testing steps involved.
  2. Then run this template for swapping slots.

Why cannot access storage account after restricting storage account to a virtual network?

  • If you are restricting access to the storage account through the private endpoints, you will not be able to access the data storage in the storage account through the portal or otherwise.
  • You can give access to your secured IP address or virtual network for the data storage in the storage account, by Managing the default network access rule

After restricting storage account to a virtual network, why do I get 503 error when trying to reach the function app?

Verify and update the Application Settings under Configuration for the function app to the following:

Setting name Value Comment
AzureWebJobsStorage Storage connection string This is the connection string for a secured storage account.

Verify and update these App setting for Premium plan or Consumption plan on Windows and Premium plan on Linux:

Setting name Value Comment
WEBSITE_CONTENTAZUREFILECONNECTIONSTRING Storage connection string This is the connection string for a secured storage account.
WEBSITE_CONTENTSHARE File share The name of the file share created in the secured storage account where the project deployment files reside.

Which app settings are used with Virtual Network?

Consider the following settings when using Virtual Network:

WEBSITE_CONTENTOVERVNET = 1

  • A value of 1 enables your function app to scale when you have your storage account restricted to a virtual network. You should enable this setting when restricting your storage account to a virtual network. To learn more, see Restrict your storage account to a virtual network.
  • Supported on Premium and Dedicated (App Service) plans (Standard and higher). Not supported when running on a Consumption plan.

WEBSITE_VNET_ROUTE_ALL = 1


Why ARM template deletes and replace application settings for a function app?

This is an expected behavior that the ARM template will delete the existing app settings and replace the app settings for a function app based on the app settings present in the ARM template. The API requires the payload to contains all necessary settings which will replace the existing one entirely. There is no partial remove or patch support with existing AppSettings. For instance, if one you want to add a new setting, one needs to get existing set, add to that collection and update as a whole.

Therefore, please include all of the existing app settings in the template to preserve them. This does not apply only if the app settings block is not defined in the current template.


When to set WEBSITE_NODE_DEFAULT_VERSION app setting?

  • This setting is for Windows only. This setting is only needed when using the node language stack to specify which node.js version to use. For Example:

NOTE: Please include rest of the existing app settings in the template to preserve them.

"properties": {
    "siteConfig": {
        "appSettings": [
            {
                "name": "WEBSITE_NODE_DEFAULT_VERSION",
                "value": "~14"
            }
        ]
    }
}

Why WEBSITE_NODE_DEFAULT_VERSION is not working in Linux?

  • WEBSITE_NODE_DEFAULT_VERSION is Windows only property. Click here for more information.
  • Linux apps should use LinuxFxVersion setting.

How linuxFxVersion is added in an ARM template?

  • Linux apps should include a linuxFxVersion property under siteConfig. If you are just deploying code, the value for this is determined by your desired runtime stack in the format of runtime|runtimeVersion.
  • If you are deploying a custom container image, you must specify it with linuxFxVersion and include configuration that allows your image to be pulled, as in Web App for Containers. Also, set WEBSITES_ENABLE_APP_SERVICE_STORAGE to false, since your app content is provided in the container itself:
  • More information about setting linuxFxVersion using ARM template and using Azure CLI is available in the documentation.

When to enable alwaysOn site config?

OR Why we need to enable Always On when running on dedicated App Service Plan?

  • If you run on an App Service plan, you should enable the "alwaysOn": true setting under site config so that your function app runs correctly. On an App Service plan, the functions runtime goes idle after a few minutes of inactivity, so only HTTP triggers will "wake up" your functions. The Always on setting is available only on an App Service plan.

  • When running in a Consumption Plan or Premium Plan you should NOT enable Always On. On a Consumption plan the platform activates function apps automatically and on a Premium plan the platform keeps your desired number of pre-warmed instances always on automatically.


How can I validate ARM Template?

All client tools are syntactically validating the ARM Template. If the validation fails, then a similar error message will be displayed in json format. For example:

{"error":{"code":"InvalidTemplate","message":"Deployment template validation failed: 'The resource 'Microsoft.Web/sites/func-xyz' is not defined in the template. Please see https://aka.ms/arm-template for usage details.'.","additionalInfo":[{"type":"TemplateViolation","info":{"lineNumber":0,"linePosition":0,"path":""}}]}}

On DevOps:

Azure Resource Group Deployment task can be used for deployment as well as validation. You can add the task with deploymentMode: 'Validation' using the following json format to run the same validation independently before deployment and get more information from the error message. For example:

- task: AzureResourceManagerTemplateDeployment@3
  inputs:
    deploymentScope: 'Resource Group'
    subscriptionId: # Required subscription ID
    action: 'Create Or Update Resource Group'
    resourceGroupName: # Required resource group name
    location: # Required when action == Create Or Update Resource Group
    templateLocation: 'Linked artifact'
    csmFile: # Required when  TemplateLocation == Linked Artifact
    csmParametersFile: # Optional
    deploymentMode: 'Validation'

On Azure CLI:

Install the latest version of Azure CLI.

You can use the az deployment group validate command to validate your ARM Template pre-deployment. For example:

az deployment group validate --resource-group <resource-group-name> --template-file <template-file-location> --parameters functionAppName='<function-app-name>' packageUri='<zip-package-location>'

For further troubleshooting, you can setup a test resource group to look out for preflight error and deployment error

On Visual Studio Code:

On Visual Studio Code, install the latest Azure Resource Manager Tools extension.

This extension catches syntactically errors in your ARM Template pre-deployment. Here are couple of visual examples of errors.


How can I add wait time or delay between resources in my ARM template?

You can add wait time or delay between resources using deployment deploymentScripts in your ARM template like below. Here the dependsOn should include the resource after which you want to add a wait time.

    {
      "type": "Microsoft.Resources/deploymentScripts",
      "apiVersion": "2020-10-01",
      "kind": "AzurePowerShell",
      "name": "WaitSection",
      "location": "[parameters('location')]",
      "dependsOn": [
        "[resourceId('Microsoft.Web/sites', parameters('functionAppName'))]"
      ],
      "properties": {
        "azPowerShellVersion": "7.0",
        "scriptContent": "start-sleep -Seconds 60",
        "cleanupPreference": "Always",
        "retentionInterval": "PT1H"
      }
    }

Whichever resource we want to create after wait time should have a dependsOn block like below.

      "dependsOn": [
        "WaitSection"
      ]
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