defaultDocuments setting not getting created via the Bicep template

Question

I have a bicep template that creates the AppService Plan and the WebApp. I'm playing around with the SiteConfig settings to setup Default Documents, I've tried adding that via Microsoft.Web/sites@2020-06-01 as well as via Microsoft.Web/sites/config@2022-03-01' but haven't had any luck. I've tried searching to see if there is something I am missing when setting up defaultDocuments but couldn't find anything. Does anyone here know why my template isn't setting defaultdocuments? I am able to see them when I create the App Service via Visual studio but I need to do it via bicep. After creating the AppService via VS, I also looked at the template to make sure I was doing it correctly and I dont see any differences.

@description('Web app name.')
@minLength(2)
param appServiceName string = 'QSCloudDashboard' // Generate unique String for web app name

@description('Describes plan\'s pricing tier and instance size. Check details at https://azure.microsoft.com/en-us/pricing/details/app-service/')
@allowed([
  'F1'
  'D1'
  'B1'
  'B2'
  'B3'
  'S1'
  'S2'
  'S3'
  'P1'
  'P2'
  'P3'
  'P4'
])
param sku string = 'B2' // The SKU of App Service Plan

param location string = resourceGroup().location // Location for all resources

@description('The language stack of the app.')
@allowed([
  '.net'
  'php'
  'node'
  'html'
])
param language string = '.net'

var configReference = {
  '.net': {
    comments: '.Net app. No additional configuration needed.'
  }
  html: {
    comments: 'HTML app. No additional configuration needed.'
  }
  php: {
    phpVersion: '7.4'
  }
}

var appServicePlanName = toLower('${appServiceName}-AppServicePlan')


resource appServicePlan 'Microsoft.Web/serverfarms@2020-06-01' = {
  name: appServicePlanName
  location: location
  properties: {
    reserved: true
  }
  sku: {
    name: sku
  }
}

resource appService 'Microsoft.Web/sites@2020-06-01' = {
  name: appServiceName
  location: location
  kind: 'app'
  identity: {
    type: 'SystemAssigned'
  }
  properties: {
    enabled: true
    siteConfig: union(configReference[language],{
      minTlsVersion: '1.2'
      linuxFxVersion: 'DOTNETCORE|6.0'
      //netFrameworkVersion:'dotnet'
      //numberOfWorkers: 1
    //   defaultDocuments: [
    //     'Default.htm'
    //     'Default.html'
    //     'Default.asp'
    //     'index.htm'
    //     'index.html'
    //     'iisstart.htm'
    //     'default.aspx'
    //     'index.php'
    //     'hostingstart.html'
    // ]
      scmMinTlsVersion: '1.2'
      ftpsState: 'AllAllowed'
      acrUseManagedIdentityCreds: false
      alwaysOn: false
      http20Enabled: false
      functionAppScaleLimit: 0
      minimumElasticInstanceCount: 0
      appSettings: [
        {
          name: 'WEBSITE_NODE_DEFAULT_VERSION'
          value: '6.9.1'
        }
        {
          name: 'APPINSIGHTS_CONNECTIONSTRING'
          value: 'InstrumentationKey=1caef12c-6950-4ffb-9edf-d552e0b84643;IngestionEndpoint=https://eastus-5.in.applicationinsights.azure.com/;LiveEndpoint=https://eastus.livediagnostics.monitor.azure.com/'
        }
        {
          name: 'ApplicationInsightsAgent_EXTENSION_VERSION'
          value: '~2'
        }
        {
          name: 'DiagnosticServices_EXTENSION_VERSION'
          value: '~3'
        }
      ]
    })
    serverFarmId: appServicePlan.id
    reserved: false
    isXenon: false
    hyperV: false
    httpsOnly: true
    scmSiteAlsoStopped: false
    clientAffinityEnabled: true
    clientCertEnabled: false
    clientCertMode: 'Required'
    hostNamesDisabled: false
    containerSize: 0
    dailyMemoryTimeQuota: 0
    redundancyMode: 'None'
  }
}

resource appService_name_web 'Microsoft.Web/sites/config@2022-03-01' = {
   parent: appService
   name: 'web'
   location: 'East US'
   properties: {
     numberOfWorkers: 1
     defaultDocuments: [
      'Default.htm'
      'Default.html'
      'Default.asp'
      'index.htm'
      'index.html'
      'iisstart.htm'
      'default.aspx'
      'index.php'
      'hostingstart.html'
    ]
  }
}

Answer 1

Setting defaultDocuments in your appService_name_web should work, but I believe your appService had some funky config inside of it. A few small changes, we'll simplify appService a bit and try moving your config to your appService_name_web section.

resource appService 'Microsoft.Web/sites@2020-06-01' = {
  name: appServiceName
  location: location
  kind: 'app'
  identity: {
    type: 'SystemAssigned'
  }
  properties: {
    enabled: true
    siteConfig: {
      alwaysOn: true
      defaultDocuments: []
    }
    httpsOnly: true
    serverFarmId: appServicePlan.id
    clientAffinityEnabled: true
    clientCertEnabled: false
  }
}

Then in your config:

resource appService_name_web 'Microsoft.Web/sites/config@2022-03-01' = {
   parent: appService
   name: 'web'
   properties: {
     numberOfWorkers: 1
     defaultDocuments: [
      'Default.htm'
      'Default.html'
      'Default.asp'
      'index.htm'
      'index.html'
      'iisstart.htm'
      'default.aspx'
      'index.php'
      'hostingstart.html'
    ]
    minTlsVersion: '1.2'
    linuxFxVersion: 'DOTNETCORE|6.0'
    scmMinTlsVersion: '1.2'
    ftpsState: 'AllAllowed'
    acrUseManagedIdentityCreds: false
    http20Enabled: false
    functionAppScaleLimit: 0
    minimumElasticInstanceCount: 0
  }
}

You can break out a new appSettings section as well if you'd like:

resource appService_name_web_appSettings 'Microsoft.Web/sites/config@2022-03-01' = {
   parent: appService
   name: 'appsettings'
   properties: {
     appSettings: {
       'WEBSITE_NODE_DEFAULT_VERSION': '6.9.1'
       'APPINSIGHTS_CONNECTIONSTRING': 'InstrumentationKey=1caef12c-6950-4ffb-9edf-d552e0b84643;IngestionEndpoint=https://eastus-5.in.applicationinsights.azure.com/;LiveEndpoint=https://eastus.livediagnostics.monitor.azure.com/'
       'ApplicationInsightsAgent_EXTENSION_VERSION': '~2'
       'DiagnosticServices_EXTENSION_VERSION': '~3'
     }
  }