Add support for web app slots

https://docs.microsoft.com/en-us/azure/templates/microsoft.web/2018-02-01/sites/slots

Would also be useful to be able to make app settings “slot sticky”. I can’t find any official documentation or reference but I’ve been using the following in my ARM templates.

{
  "name": "[variables('webAppName')]",
  "type": "Microsoft.Web/sites",
  "apiVersion": "2016-08-01",
  "location": "[resourceGroup().location]",
  "properties": {
    "serverFarmId": "[variables('appServiceResourceId')]",
    "siteConfig": {
      "connectionStrings": [
        {
          "name": "Database",
          "connectionString": "[variables('sqlConnectionString')]",
          "type": "SQLAzure"
        },
        {
          "name": "ServiceBus",
          "connectionString": "[variables('serviceBusConnectionString')]",
          "type": "Custom"
        }
      ],
      "appSettings": [
        {
          "name": "ASPNETCORE_ENVIRONMENT",
          "value": "[parameters('aspNetEnvironment')]"
        },
        {
          "name": "AllowedOrigins",
          "value": "[variables('allowedOrigins')]"
        }
      ]
    }
  },
  "resources": [
    {
      "type": "config",
      "name": "slotconfignames",
      "apiVersion": "2016-08-01",
      "properties": {
        "connectionStringNames": [
          "Database",
          "ServiceBus"
        ],
        "appSettingNames": [
          "ASPNETCORE_ENVIRONMENT",
          "AllowedOrigins"
        ]
      },
      "dependsOn": [
        "[variables('webAppName')]"
      ]
    }
  ]
}

[TheRSP]

@isaacabraham I should have a little bit of time coming up and this will soon be a priority for my company.

What do you think about adding these new keywords?

• slots - takes a string list of slot names (overrides any previous value)
• zip_deploy_slot - takes a slot name and zip path to deploy to the given slot

Further improvements could then be to add

• add_slot_setting/add_slot_settings for sticky settings
• add_slot_connection_string/add_slot_connection_strings for sticky connection strings

Is there an alternative API you would prefer?

[fraxu]

I’m currently using the following quick hack to get slots working.

type Slot =
    { Name : ResourceName
      Location : Location
      SiteName: ResourceName
      ServicePlanName: ResourceName
      AutoSwapSlot: Slot option }
    interface IArmResource with
        member this.ResourceName = this.Name
        member this.JsonModel =
            {| name = sprintf "%s/%s" this.SiteName.Value this.Name.Value
               ``type`` = "Microsoft.Web/sites/slots"
               apiVersion = "2020-06-01"
               location = this.Location.ArmValue
               tags = {||}
               properties = 
                    {| serverFarmId = this.ServicePlanName.Value
                       siteConfig = 
                       {| autoSwapSlotName = this.AutoSwapSlot |> Option.map(fun s -> s.Name.Value) |> Option.toObj |} 
                    |}
            |} :> _

let testWebApp = webApp {
    name "test"
    sku WebApp.Sku.S1
}

let productionSlot = 
    { Slot.Name = ResourceName "production"
      SiteName = testWebApp.Name
      ServicePlanName = testWebApp.ServicePlanName
      Location = Location.WestEurope
      AutoSwapSlot = None }

let stagingSlot =
    { Slot.Name = ResourceName "staging"
      SiteName = testWebApp.Name
      ServicePlanName = testWebApp.ServicePlanName
      Location = Location.WestEurope
      AutoSwapSlot = Some productionSlot }

let deployment = arm {
    location Location.WestEurope
    add_resource testWebApp
    add_resource stagingSlot
    add_resource productionSlot

For basic slots support I guess we would need at least:

• Custom operator in WebApp builder to make adding slots easy
• autoSwapSlotName to Site Arm as well
• Slot builder?
• Documentation

I’m happy to help with this if needed!