How to use sticky staging slots in Azure Arm Templates

Question

How can you deploy sticky settings to a production app slot in azure web apps using ARM templates without overwriting the existing app settings?

I'm using Azure ARM templates to deploy my environment and code releases. The environment has both Staging and Production slots. Part of the deployment is deploying AppSettings. We deploy to Staging, test, then swap to prod.

This system has been working well until now, when I need to deploy a sticky AppSetting to prod. Normally, the deployments are incremental, but when I try to create a sticky setting for production, all of the other settings get wiped out.

I'm using slotconfignames to specify the sticky variables in the prod slot

{
      "apiVersion": "2015-08-01",
      "name": "slotconfignames",
      "type": "config",
      "dependsOn": [
        "[resourceId('Microsoft.Web/Sites', variables('webSiteName'))]"
      ],
      "properties": {
        "appSettingNames": [ "WEBSITE_LOCAL_CACHE_OPTION", "WEBSITE_LOCAL_CACHE_SIZEINMB" ]
      }
    }

I've tried creating separate resources for the prod appsettings and the stage appsettings - when I do, the prod slot appsettings are completely overwritten. This is somewhat expected:

 {
      "apiVersion": "2015-08-01",
      "type": "config",
      "name": "appsettings",
      "dependsOn": [
        "[resourceId('Microsoft.Web/sites/', variables('webSiteName'))]"
      ],

      "properties": {
        "WEBSITE_LOCAL_CACHE_OPTION": "Always",
        "WEBSITE_LOCAL_CACHE_SIZEINMB": "2000"
      }
    },

If I make those same settings as part of the stage slot settings, then they aren't set on prod, but are set as sticky on the stage slot.

{
    "name": "appsettings",
    "type": "config",
    "apiVersion": "2015-08-01",
    "dependsOn": [
      "[variables('stagingSlotName')]",
      //"[concat('Microsoft.Web/sites/', variables('webSiteName'))]",
      "MSDeploy",
      "[concat('Microsoft.Resources/deployments/', 'AppStorage')]"
    ],
    "tags": {
      "displayName": "uisettings",
      "environment": "[parameters('environmentName')]",
      "serviceGroup": "[variables('serviceGroupName')]"
    },
    "properties": {
      ...othersettingshere...         
      "WEBSITE_LOCAL_CACHE_OPTION": "Always",
      "WEBSITE_LOCAL_CACHE_SIZEINMB": "2000"
    }
  },

Answer 1

when I need to deploy a sticky AppSetting to prod. Normally, the deployments are incremental, but when I try to create a sticky setting for production, all of the other settings get wiped out.

Based on my test, as you said, the App settings that are not defined in your ARM template will be wiped out. Please make sure you include all App settings in your ARM template when you specify sticky slot settings.

{
  "name": "appsettings",
  "type": "config",
  "apiVersion": "2015-08-01",
  "dependsOn": [
    "[concat('Microsoft.Web/sites/', variables('webSiteName'))]"
  ],
  "tags": {
    "displayName": "uisettings"
  },
  "properties": {
    "AppSettingKey1": "myvalue",
    //your other appsettings
    "WEBSITE_LOCAL_CACHE_OPTION": "Always",
    "WEBSITE_LOCAL_CACHE_SIZEINMB": "2000"
  }
},
{
  "apiVersion": "2015-08-01",
  "name": "slotconfignames",
  "type": "config",
  "dependsOn": [
    "[concat('Microsoft.Web/sites/', variables('webSiteName'))]"
  ],
  "properties": {
    "appSettingNames": [ "WEBSITE_LOCAL_CACHE_OPTION", "WEBSITE_LOCAL_CACHE_SIZEINMB" ]
  }
}