Example deployment slots for both app service and function apps in Azure

deploymentslots.azuredeploy.json

{
    "$schema": "https://schema.management.azure.com/schemas/2015-01-01/deploymentTemplate.json#",
    "contentVersion": "1.0.0.0",
    "parameters": {
    },
    "variables": {
        "appServicePlanName": "myapp-swaptest-asp",
        "site_name": "myapp-swaptest-app",
        "functionapp_name": "myapp-swaptest-func",
        "stagingslot_name": "staging"
    },
    "resources": [
        {
            "type": "Microsoft.Web/serverfarms",
            "sku": {
                "name": "S1"
            },
            "kind": "app",
            "name": "[variables('appServicePlanName')]",
            "apiVersion": "2016-09-01",
            "location": "[resourceGroup().location]",
            "scale": null,
            "properties": {
                "name": "[variables('appServicePlanName')]",
                "perSiteScaling": false,
                "reserved": false,
                "targetWorkerCount": 0,
                "targetWorkerSizeId": 0
            },
            "dependsOn": [
            ]
        },

        {
            "type": "Microsoft.Web/sites",
            "kind": "functionapp",
            "name": "[variables('functionapp_name')]",
            "apiVersion": "2016-08-01",
            "location": "[resourceGroup().location]",
            "scale": null,
            "properties": {
                "enabled": true,
                "serverFarmId": "[resourceId('Microsoft.Web/serverfarms', variables('appServicePlanName'))]"
            },
            "dependsOn": [
                "[resourceId('Microsoft.Web/serverfarms', variables('appServicePlanName'))]"
            ],
            "resources": [
                {
                    "type": "config",
                    "apiVersion": "2018-11-01",
                    "name": "/web",
                    "dependsOn": [
                        "[resourceId('Microsoft.Web/sites', variables('functionapp_name'))]"
                    ],
                    "properties": {
                        "alwaysOn": true,
                        "cors": {
                            "allowedOrigins": [
                                "https://functions.azure.com",
                                "https://functions-staging.azure.com",
                                "https://functions-next.azure.com",
                                "https://production.com"
                            ],
                            "supportCredentials": false
                        }
                    }
                },
                {
                    "apiVersion": "2015-08-01",
                    "name": "slotconfignames",
                    "type": "config",
                    "dependsOn": [
                        "[resourceId('Microsoft.Web/sites', variables('functionapp_name'))]"
                    ],
                    "properties": {
                        "appSettingNames": [
                            "IsDisabled"
                        ]
                    }
                },
                {
                    "type": "slots",
                    "apiVersion": "2018-11-01",
                    "name": "[concat('/', variables('stagingslot_name'))]",
                    "dependsOn": [
                        "[resourceId('Microsoft.Web/sites', variables('functionapp_name'))]"
                    ],
                    "location": "[resourceGroup().location]",
                    "kind": "functionapp",
                    "properties": {
                        "enabled": true,
                        "serverFarmId": "[resourceId('Microsoft.Web/serverfarms', variables('appServicePlanName'))]",
                        "clientAffinityEnabled": false,
                        "httpsOnly": true
                    },
                    "resources": [
                        {
                            "type": "config",
                            "apiVersion": "2018-11-01",
                            "name": "/web",
                            "dependsOn": [
                                "[resourceId('Microsoft.Web/sites/slots', variables('functionapp_name'), variables('stagingslot_name'))]"
                            ],
                            "properties": {
                            "alwaysOn": false,
                                "cors": {
                                    "allowedOrigins": [
                                        "https://functions.azure.com",
                                        "https://functions-staging.azure.com",
                                        "https://functions-next.azure.com",
                                        "https://staging.com"
                                    ],
                                    "supportCredentials": false
                                },
                                "http20Enabled": true
                            }
                        },
                        {
                            "apiVersion": "2015-08-01",
                            "name": "appsettings",
                            "type": "config",
                            "dependsOn": [
                                "[resourceId('Microsoft.Web/sites/slots', variables('functionapp_name'), variables('stagingslot_name'))]"
                            ],
                            "properties": {
                                "myslotvar": "2",
                                "FUNCTIONS_EXTENSION_VERSION": "~3",
                                "FUNCTIONS_EXTENSION_RUNTIME": "dotnet",
                                "FUNCTIONS_WORKER_RUNTIME": "dotnet",
                                "IsDisabled": "1"
                            }
                        }
                    ]
                }
            ]
        },

        {
            "type": "Microsoft.Web/sites",
            "kind": "app",
            "name": "[variables('site_name')]",
            "apiVersion": "2015-08-01",
            "location": "[resourceGroup().location]",
            "tags": {
            },
            "scale": null,
            "properties": {
                "enabled": true,
                "serverFarmId": "[resourceId('Microsoft.Web/serverfarms', variables('appServicePlanName'))]"
            },
            "dependsOn": [
                "[resourceId('Microsoft.Web/serverfarms', variables('appServicePlanName'))]"
            ],
            "resources": [
                {
                    "type": "config",
                    "name": "/web",
                    "apiVersion": "2016-08-01",
                    "location": "[resourceGroup().location]",
                    "tags": {
                    },
                    "properties": {
                        "alwaysOn": true
                    },
                    "dependsOn": [
                        "[resourceId('Microsoft.Web/sites', variables('site_name'))]"
                    ]
                },
                {
                    "apiVersion": "2015-08-01",
                    "name": "slotconfignames",
                    "type": "config",
                    "dependsOn": [
                        "[resourceId('Microsoft.Web/sites', variables('site_name'))]"
                    ],
                    "properties": {
                        "appSettingNames": [
                            "WEBJOBS_STOPPED"
                        ]
                    }
                },
                {
                    "type": "slots",
                    "apiVersion": "2018-11-01",
                    "location": "[resourceGroup().location]",
                    "name": "[concat('/', variables('stagingslot_name'))]",
                    "dependsOn": [
                        "[resourceId('Microsoft.Web/sites', variables('site_name'))]"
                    ],
                    "properties": {
                        "enabled": true,
                        "serverFarmId": "[resourceId('Microsoft.Web/serverfarms', variables('appServicePlanName'))]",
                        "reserved": false,
                        "clientAffinityEnabled": false,
                        "httpsOnly": true
                    },
                    "resources": [
                        {
                            "type": "config",
                            "name": "/web",
                            "apiVersion": "2018-11-01",
                            "dependsOn": [
                                "[resourceId('Microsoft.Web/sites/slots', variables('site_name'),  variables('stagingslot_name'))]"
                            ],
                            "properties": {
                                "http20Enabled": true,
                                "webSocketsEnabled": true
                            }
                        },
                        {
                            "type": "config",
                            "name": "appsettings",
                            "apiVersion": "2015-08-01",
                            "dependsOn": [
                                "[resourceId('Microsoft.Web/sites/slots', variables('site_name'), variables('stagingslot_name'))]"
                            ],
                            "properties": {
                                "my_variable": "test",
                                "my_slot_variable": "test",
                                "WEBJOBS_STOPPED": "1"
                            }
                        }
                    ]
                }
            ]
        }
    ]
}