template.json

{
    "$schema": "https://schema.management.azure.com/schemas/2015-01-01/deploymentTemplate.json#",
    "contentVersion": "1.0.0.0",
    "parameters": {
        "siteName": {
            "type": "string",
            "metadata": {
                "description": "Name of azure web app"
            }
        }
    },
    "variables": {
        "hostingPlanName": "[concat(parameters('siteName'), 'serviceplan')]"
    },
    "resources": [
        {
            "type": "Microsoft.Web/sites",
            "name": "[parameters('siteName')]",
            "properties": {
                "siteConfig": {
                    "appSettings": [
                        {
                            "name": "DOCKER_CUSTOM_IMAGE_NAME",
                            "value": "prashanthmadi/azure-appservice-nginx:1.13"
                        },
                        {
                            "name": "WEBSITES_ENABLE_APP_SERVICE_STORAGE",
                            "value": true
                        }
                    ],
                    "httpLoggingEnabled": true,
                    "logsDirectorySizeLimit": 36
                },
                "name": "[parameters('siteName')]",
                "serverFarmId": "[variables('hostingPlanName')]",
                "hostingEnvironment": ""
            },
            "apiVersion": "2016-03-01",
            "location": "[resourceGroup().location]",
            "dependsOn": [
                "[variables('hostingPlanName')]"
            ]
        },
        {
            "apiVersion": "2016-09-01",
            "name": "[variables('hostingPlanName')]",
            "type": "Microsoft.Web/serverfarms",
            "location": "[resourceGroup().location]",
            "properties": {
                "name": "[variables('hostingPlanName')]",
                "workerSizeId": "1",
                "reserved": true,
                "numberOfWorkers": "1",
                "hostingEnvironment": ""
            },
            "sku": {
                "Tier": "Standard",
                "Name": "S1"
            },
            "kind": "linux"
        }
    ]
}