Bicep - Cannot access Function Key on B1 plan

@Michał Jełowicki Thanks for reaching out to Microsoft Q&A, apologize for any inconvenience caused on this.

When we have tested this in our local environment, we are also not able to access the function app(which are running on dedicated app service plan) it is failing with internal server error from host runtime.

I am checking with internal team on this and will update you here once I hear back from them.

@Michał Jełowicki Thanks for your patience on this could you please retry the operation and let us know if you are still facing the issue.

@VenkateshDodda-MSFT Unfortunately I still do.

@Michał Jełowicki Thanks for your response. Could you please share your complete bicep template to check and assist you further.

@VenkateshDodda-MSFT Here you go, thanks for your assistance

param app_service_plan_name string
param function_name
param vault_name string
param func_storage_name 
param tenant_id string
param region_uppercase
param region string

// (2) App Service Plan + Function Storage + Function App
resource appServicePlan 'Microsoft.Web/serverfarms@2022-09-01' = {
  name: app_service_plan_name
  location: region_uppercase
  sku: {
    name: 'B1'
    tier: 'Basic'
    size: 'B1'
    family: 'B'
    capacity: 1
  }
  kind: 'linux'
  properties: {
    reserved: true
  }
}

// (2b) Function Storage 
resource functionStorage 'Microsoft.Storage/storageAccounts@2023-01-01' = {
  location: region
  name: func_storage_name
  sku: {
    name: 'Standard_LRS'
  }
  kind: 'Storage'
  properties: {
    minimumTlsVersion: 'TLS1_2'
  }
}

resource functionStorageDefault 'Microsoft.Storage/storageAccounts/blobServices@2023-01-01' = {
  parent: functionStorage
  name: 'default'
}

resource functionStorageServices 'Microsoft.Storage/storageAccounts/fileServices@2023-01-01' = {
  parent: functionStorage
  name: 'default'
}

resource functionStorageContainer 'Microsoft.Storage/storageAccounts/blobServices/containers@2023-01-01' = {
  parent: functionStorageDefault
  name: 'azure-webjobs-hosts'
}

resource functionStorageContainer2 'Microsoft.Storage/storageAccounts/blobServices/containers@2023-01-01' = {
  parent: functionStorageDefault
  name: 'azure-webjobs-secrets'
}

// (2c) Function App
resource functionApp 'Microsoft.Web/sites@2022-09-01' = {
  name: function_name
  location: region_uppercase
  kind: 'functionapp,linux'
  identity: {
    type: 'SystemAssigned'
  }
  properties: {
    enabled: true
    serverFarmId: appServicePlan.id
    siteConfig: {
      appSettings: [
        {
          name: 'FUNCTIONS_WORKER_RUNTIME'
          value: 'python'
        }
        {
          name: 'FUNCTIONS_EXTENSION_VERSION'
          value: '~4'
        }
        {
          name: 'AzureWebJobsStorage'
          value: 'DefaultEndpointsProtocol=https;AccountName=${func_storage_name};AccountKey=${functionStorage.listKeys().keys[0].value};EndpointSuffix=core.windows.net'
        }
        {
          name: 'AzureWebJobsFeatureFlags'
          value: 'EnableWorkerIndexing'
        }
      ]
      netFrameworkVersion: 'v4.0'
      linuxFxVersion: 'Python|3.11'
      alwaysOn: true
    }
  }
}

// (5) Key Vault
resource keyVault 'Microsoft.KeyVault/vaults@2023-07-01' = {
  name: vault_name
  location: region
  properties: {
    sku: {
      family: 'A'
      name: 'standard'
    }
    tenantId: tenant_id
    accessPolicies: [
      {
        tenantId: tenant_id
        objectId: rg_owner_id
        permissions: {
          keys: [
            'Get'
            'List'
            'Update'
            'Create'
            'Import'
            'Delete'
            'Recover'
            'Backup'
            'Restore'
            'GetRotationPolicy'
            'SetRotationPolicy'
            'Rotate'
            'Encrypt'
            'Decrypt'
            'UnwrapKey'
            'WrapKey'
            'Verify'
            'Sign'
            'Purge'
            'Release'
          ]
          secrets: [
            'Get'
            'List'
            'Set'
            'Delete'
            'Recover'
            'Backup'
            'Restore'
            'Purge'
          ]
          certificates: [
            'Get'
            'List'
            'Update'
            'Create'
            'Import'
            'Delete'
            'Recover'
            'Backup'
            'Restore'
            'ManageContacts'
            'ManageIssuers'
            'GetIssuers'
            'ListIssuers'
            'SetIssuers'
            'DeleteIssuers'
            'Purge'
          ]
        }
      }
      {
        tenantId: tenant_id
        objectId: functionApp.identity.principalId
        permissions: {
          certificates: [
            'Get'
            'List'
          ]
          keys: [
            'Get'
            'List'
          ]
          secrets: [
            'Get'
            'List'
          ]
        }
      }
      {
        tenantId: tenant_id
        objectId: dataFactory.identity.principalId
        permissions: {
          certificates: [
            'get'
            'list'
          ]
          keys: [
            'get'
            'list'
          ]
          secrets: [
            'get'
            'list'
          ]
        }
      }
    ]
  }
}

resource secretAppRegistrationSecret 'Microsoft.KeyVault/vaults/secrets@2022-07-01' = {
  parent: keyVault
  name: 'secret-pbimon-app-reg-secret'
  properties: {
    value: app_reg_secret
  }
}