An ARM template for deploying a containerized AppService, where the container resides in a resource group outside of your apps resource group (as is recommended by Azure).

container-webapp-template.json

{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "webAppName": {
      "type": "String"
    },
    "hostingPlanName": {
      "type": "String"
    },
    "appInsightsLocation": {
      "type": "String"
    },
    "sku": {
      "defaultValue": "Standard",
      "type": "String"
    },
    "registryName": {
      "type": "String"
    },
    "imageName": {
      "type": "String"
    },
    "registryResourceGroup": {
      "type": "String"
    },
    "registryResourceId": {
      "defaultValue": "[resourceId(subscription().subscriptionId, parameters('registryResourceGroup'), 'Microsoft.ContainerRegistry/registries', parameters('registryName'))]",
      "type": "String"
    },
    "startupCommand": {
      "defaultValue": "",
      "type": "String"
    }
  },
  "resources": [
    {
      "type": "Microsoft.Web/sites",
      "name": "[parameters('webAppName')]",
      "apiVersion": "2020-12-01",
      "location": "[resourceGroup().location]",
      "tags": {
        "[concat('hidden-related:', '/subscriptions/', subscription().subscriptionId,'/resourcegroups/', resourceGroup().name, '/providers/Microsoft.Web/serverfarms/', parameters('hostingPlanName'))]": "empty"
      },
      "properties": {
        "name": "[parameters('webAppName')]",
        "siteConfig": {
          "appSettings": [
            {
              "name": "DOCKER_REGISTRY_SERVER_URL",
              "value": "[reference(parameters('registryResourceId'), '2019-05-01').loginServer]"
            },
            {
              "name": "DOCKER_REGISTRY_SERVER_USERNAME",
              "value": "[listCredentials(parameters('registryResourceId'), '2019-05-01').username]"
            },
            {
              "name": "DOCKER_REGISTRY_SERVER_PASSWORD",
              "value": "[listCredentials(parameters('registryResourceId'), '2019-05-01').passwords[0].value]"
            },
            {
              "name": "WEBSITES_ENABLE_APP_SERVICE_STORAGE",
              "value": "false"
            },
            {
              "name": "APPINSIGHTS_INSTRUMENTATIONKEY",
              "value": "[reference(resourceId('microsoft.insights/components/', parameters('webAppName')), '2015-05-01').InstrumentationKey]"
            }
          ],
          "appCommandLine": "[parameters('startupCommand')]",
          "linuxFxVersion": "[concat('DOCKER|', reference(parameters('registryResourceId'), '2019-05-01').loginServer, '/', parameters('imageName'))]"
        },
        "serverFarmId": "[concat('/subscriptions/', subscription().subscriptionId,'/resourcegroups/', resourceGroup().name, '/providers/Microsoft.Web/serverfarms/', parameters('hostingPlanName'))]",
        "hostingEnvironment": ""
      },
      "dependsOn": [
        "[concat('Microsoft.Web/serverfarms/', parameters('hostingPlanName'))]",
        "[resourceId('microsoft.insights/components/', parameters('webAppName'))]"
      ]
    },
    {
      "type": "Microsoft.Web/serverfarms",
      "sku": {
        "Tier": "[first(skip(split(parameters('sku'), ' '), 1))]",
        "Name": "[first(split(parameters('sku'), ' '))]"
      },
      "kind": "linux",
      "name": "[parameters('hostingPlanName')]",
      "apiVersion": "2016-09-01",
      "location": "[resourceGroup().location]",
      "properties": {
        "name": "[parameters('hostingPlanName')]",
        "workerSizeId": "0",
        "reserved": true,
        "numberOfWorkers": "1",
        "hostingEnvironment": ""
      }
    },
    {
      "type": "Microsoft.Insights/components",
      "name": "[parameters('webAppName')]",
      "apiVersion": "2014-04-01",
      "location": "[parameters('appInsightsLocation')]",
      "tags": {
        "[concat('hidden-link:', resourceGroup().id, '/providers/Microsoft.Web/sites/', parameters('webAppName'))]": "Resource"
      },
      "properties": {
        "applicationId": "[parameters('webAppName')]",
        "Request_Source": "AzureTfsExtensionAzureProject"
      }
    }
  ]
}