Azure function staging slot swap bug when deployed via ARM template

Question

I have created an Azure function app(consumption plan) using ARM template. After i deploy code and perform a swap operation(VSTS task) both the production and staging slot have the new code. But i expected the staging slot to have the old code after the swap operation, is this a known bug in Azure functions ? Or do i have to do anything extra

"resources": [
    {
      "name": "CampaignSyncJob",
      "type": "Microsoft.Resources/deployments",
      "apiVersion": "2016-09-01",
      "dependsOn": [],
      "properties": {
        "mode": "Incremental",
        "templateLink": {
          "uri": "[concat(parameters('artifactsLocation'), '/', variables('linkedTemplateFolderName'), '/', variables('webAppTemplateFileName'), parameters('artifactsLocationSasToken'))]",
          "contentVersion": "1.0.0.0"
        },
        "parameters": {
          "appServicePlanName": {
            "value": "[reference('ReleaseParams').outputs.webApp.value.appServicePlanName]"
          },
          "appServiceName": {
            "value": "[reference('ReleaseParams').outputs.webApp.value.appServiceName]"
          },
          "artifactsLocation": {
            "value": "[parameters('artifactsLocation')]"
          },
          "artifactsLocationSasToken": {
            "value": "[parameters('artifactsLocationSasToken')]"
          },
          "packageFolder": {
            "value": "CampaignSyncJob"
          },
          "packageFileName": {
            "value": "package.zip"
          },
          "appSettings": {
            "value": {
              "AzureWebJobsStorage": "[concat('DefaultEndpointsProtocol=https;AccountName=', variables('storageAccountName'), ';AccountKey=', listKeys(variables('storageAccountid'),'2015-05-01-preview').key1)]",
              "WEBSITE_CONTENTAZUREFILECONNECTIONSTRING": "[concat('DefaultEndpointsProtocol=https;AccountName=', variables('storageAccountName'), ';AccountKey=', listKeys(variables('storageAccountid'),'2015-05-01-preview').key1)]",
              "WEBSITE_CONTENTSHARE": "[toLower(variables('appServiceName'))]",
              "FUNCTIONS_EXTENSION_VERSION": "~2",
              "WEBSITE_NODE_DEFAULT_VERSION": "6.5.0",
              "MSDEPLOY_RENAME_LOCKED_FILES": "1",
              "AppInsights_InstrumentationKey": "[variables('appInsightsInstrumentationKey')]",
              "StickySetting": "StuckToProduction1"
            }
          },
          "slotAppSettings": {
            "value": {
              "AzureWebJobsStorage": "[concat('DefaultEndpointsProtocol=https;AccountName=', variables('storageAccountName'), ';AccountKey=', listKeys(variables('storageAccountid'),'2015-05-01-preview').key1)]",
              "WEBSITE_CONTENTAZUREFILECONNECTIONSTRING": "[concat('DefaultEndpointsProtocol=https;AccountName=', variables('storageAccountName'), ';AccountKey=', listKeys(variables('storageAccountid'),'2015-05-01-preview').key1)]",
              "WEBSITE_CONTENTSHARE": "[toLower(variables('appServiceName'))]",
              "FUNCTIONS_EXTENSION_VERSION": "~2",
              "WEBSITE_NODE_DEFAULT_VERSION": "6.5.0",
              "MSDEPLOY_RENAME_LOCKED_FILES": "1",
              "AppInsights_InstrumentationKey": "[variables('appInsightsInstrumentationKey')]",
              "StickySetting": "StuckToStaging1"
            }
          },
          "slotName": {
            "value": "[reference('ReleaseParams').outputs.webApp.value.appServiceSlotName]"
          },
          "appServiceLocation": {
            "value": "[reference('ReleaseParams').outputs.common.value.location]"
          },
          "slotSpecificAppSettingKeys": {
            "value": [
              "StickySetting"
            ]
          }
        }
      }
    },

Linked template which deploys the function app

{
      "condition": "[parameters('deployOnStagingSlot')]",
      "apiVersion": "2015-08-01",
      "name": "[concat(parameters('appServiceName'), '/', parameters('slotName'))]",
      "type": "Microsoft.Web/sites/slots",
      "location": "[parameters('appServiceLocation')]",
      "properties": {
        "serverFarmId": "[resourceId('Microsoft.Web/serverfarms', parameters('appServicePlanName'))]"
      },
      "dependsOn": [
      ],
      "resources": [
        {
          "condition": "[parameters('deployOnStagingSlot')]",
          "name": "appsettings",
          "type": "config",
          "apiVersion": "2015-08-01",
          "dependsOn": [
            "[concat('Microsoft.Web/sites/', parameters('appServiceName'), '/slots/', parameters('slotName'))]",
            "[concat('Microsoft.Web/sites/', parameters('appServiceName'), '/slots/', parameters('slotName'), '/Extensions/MSdeploy')]"
          ],
          "properties": "[parameters('slotAppSettings')]"
        },
        {
          "condition": "[parameters('deployOnStagingSlot')]",
          "name": "MSDeploy",
          "type": "extensions",
          "location": "[parameters('appServiceLocation')]",
          "apiVersion": "2015-08-01",
          "dependsOn": [
            "[concat('Microsoft.Web/sites/', parameters('appServiceName'), '/slots/', parameters('slotName'))]"
          ],
          "properties": {
            "packageUri": "[concat(parameters('artifactsLocation'), '/', parameters('packageFolder'), '/', parameters('packageFileName'), parameters('artifactsLocationSasToken'))]",
            "setParameters": {
              "IIS Web Application Name": "[parameters('slotName')]"
            }
          }
        }
      ]
    }

TJ Galama TJ Galama · Accepted Answer · 2018-08-31T10:21:49

Hmm, I know that for swapping slots within a functions app it is required to change app setting WEBSITE_CONTENTSHARE to a slot specific setting.

For this solution and other ARM issues regarding multiple slots, check out the blog of Gary Lumsden

Azure function staging slot swap bug when deployed via ARM template

1 Answers