Skip to content

Latest commit

 

History

History
273 lines (162 loc) · 12.7 KB

create-first-function-cli-python.md

File metadata and controls

273 lines (162 loc) · 12.7 KB
title description ms.date ms.topic ms.custom
Create a Python function from the command line - Azure Functions
Learn how to create a Python function from the command line, then publish the local project to serverless hosting in Azure Functions.
11/03/2020
quickstart
devx-track-python
devx-track-azurecli

Quickstart: Create a Python function in Azure from the command line

[!INCLUDE functions-language-selector-quickstart-cli]

In this article, you use command-line tools to create a Python function that responds to HTTP requests. After testing the code locally, you deploy it to the serverless environment of Azure Functions.

Completing this quickstart incurs a small cost of a few USD cents or less in your Azure account.

There is also a Visual Studio Code-based version of this article.

Configure your local environment

Before you begin, you must have the following:

Prerequisite check

Verify your prerequisites, which depend on whether you are using Azure CLI or Azure PowerShell for creating Azure resources:

Azure CLI

  • In a terminal or command window, run func --version to check that the Azure Functions Core Tools are version 3.x.

  • Run az --version to check that the Azure CLI version is 2.4 or later.

  • Run az login to sign in to Azure and verify an active subscription.

  • Run python --version (Linux/macOS) or py --version (Windows) to check your Python version reports 3.8.x, 3.7.x or 3.6.x.

Azure PowerShell

  • In a terminal or command window, run func --version to check that the Azure Functions Core Tools are version 3.x.

  • Run (Get-Module -ListAvailable Az).Version and verify version 5.0 or later.

  • Run Connect-AzAccount to sign in to Azure and verify an active subscription.

  • Run python --version (Linux/macOS) or py --version (Windows) to check your Python version reports 3.8.x, 3.7.x or 3.6.x.

Create and activate a virtual environment

In a suitable folder, run the following commands to create and activate a virtual environment named .venv. Be sure to use Python 3.8, 3.7 or 3.6, which are supported by Azure Functions.

bash

python -m venv .venv
source .venv/bin/activate

If Python didn't install the venv package on your Linux distribution, run the following command:

sudo apt-get install python3-venv

PowerShell

py -m venv .venv
.venv\scripts\activate

Cmd

py -m venv .venv
.venv\scripts\activate

You run all subsequent commands in this activated virtual environment.

Create a local function project

In Azure Functions, a function project is a container for one or more individual functions that each responds to a specific trigger. All functions in a project share the same local and hosting configurations. In this section, you create a function project that contains a single function.

  1. Run the func init command, as follows, to create a functions project in a folder named LocalFunctionProj with the specified runtime:

    func init LocalFunctionProj --python

  2. Navigate into the project folder:

    cd LocalFunctionProj

    This folder contains various files for the project, including configurations files named local.settings.json and host.json. Because local.settings.json can contain secrets downloaded from Azure, the file is excluded from source control by default in the .gitignore file.

  3. Add a function to your project by using the following command, where the --name argument is the unique name of your function (HttpExample) and the --template argument specifies the function's trigger (HTTP).

    func new --name HttpExample --template "HTTP trigger" --authlevel "anonymous"

    func new creates a subfolder matching the function name that contains a code file appropriate to the project's chosen language and a configuration file named function.json.

(Optional) Examine the file contents

If desired, you can skip to Run the function locally and examine the file contents later.

__init__.py

__init__.py contains a main() Python function that's triggered according to the configuration in function.json.

:::code language="python" source="~/functions-quickstart-templates/Functions.Templates/Templates/HttpTrigger-Python/init.py":::

For an HTTP trigger, the function receives request data in the variable req as defined in function.json. req is an instance of the azure.functions.HttpRequest class. The return object, defined as $return in function.json, is an instance of azure.functions.HttpResponse class. To learn more, see Azure Functions HTTP triggers and bindings.

function.json

function.json is a configuration file that defines the input and output bindings for the function, including the trigger type.

You can change scriptFile to invoke a different Python file if desired.

:::code language="json" source="~/functions-quickstart-templates/Functions.Templates/Templates/HttpTrigger-Python/function.json":::

Each binding requires a direction, a type, and a unique name. The HTTP trigger has an input binding of type httpTrigger and output binding of type http.

[!INCLUDE functions-run-function-test-local-cli]

Create supporting Azure resources for your function

Before you can deploy your function code to Azure, you need to create three resources:

  • A resource group, which is a logical container for related resources.
  • A Storage account, which maintains state and other information about your projects.
  • A function app, which provides the environment for executing your function code. A function app maps to your local function project and lets you group functions as a logical unit for easier management, deployment, and sharing of resources.

Use the following commands to create these items. Both Azure CLI and PowerShell are supported.

  1. If you haven't done so already, sign in to Azure:

    Azure CLI

    az login

    The az login command signs you into your Azure account.

    Azure PowerShell

    Connect-AzAccount

    The Connect-AzAccount cmdlet signs you into your Azure account.

  2. Create a resource group named AzureFunctionsQuickstart-rg in the westeurope region.

    Azure CLI

    az group create --name AzureFunctionsQuickstart-rg --location westeurope

    The az group create command creates a resource group. You generally create your resource group and resources in a region near you, using an available region returned from the az account list-locations command.

    Azure PowerShell

    New-AzResourceGroup -Name AzureFunctionsQuickstart-rg -Location westeurope

    The New-AzResourceGroup command creates a resource group. You generally create your resource group and resources in a region near you, using an available region returned from the Get-AzLocation cmdlet.

    [!NOTE] You can't host Linux and Windows apps in the same resource group. If you have an existing resource group named AzureFunctionsQuickstart-rg with a Windows function app or web app, you must use a different resource group.

  3. Create a general-purpose storage account in your resource group and region:

    Azure CLI

    az storage account create --name <STORAGE_NAME> --location westeurope --resource-group AzureFunctionsQuickstart-rg --sku Standard_LRS

    The az storage account create command creates the storage account.

    Azure PowerShell

    New-AzStorageAccount -ResourceGroupName AzureFunctionsQuickstart-rg -Name <STORAGE_NAME> -SkuName Standard_LRS -Location westeurope

    The New-AzStorageAccount cmdlet creates the storage account.

    In the previous example, replace <STORAGE_NAME> with a name that is appropriate to you and unique in Azure Storage. Names must contain three to 24 characters numbers and lowercase letters only. Standard_LRS specifies a general-purpose account, which is supported by Functions.

    The storage account incurs only a few cents (USD) for this quickstart.

  4. Create the function app in Azure:

    Azure CLI

    az functionapp create --resource-group AzureFunctionsQuickstart-rg --consumption-plan-location westeurope --runtime python --runtime-version 3.8 --functions-version 3 --name <APP_NAME> --storage-account <STORAGE_NAME> --os-type linux

    The az functionapp create command creates the function app in Azure. If you are using Python 3.7 or 3.6, change --runtime-version to 3.7 or 3.6, respectively.

    Azure PowerShell

    New-AzFunctionApp -Name <APP_NAME> -ResourceGroupName AzureFunctionsQuickstart-rg -StorageAccount <STORAGE_NAME> -FunctionsVersion 3 -RuntimeVersion 3.8 -Runtime python -Location 'West Europe'

    The New-AzFunctionApp cmdlet creates the function app in Azure. If you're using Python 3.7 or 3.6, change -RuntimeVersion to 3.7 or 3.6, respectively.

    In the previous example, replace <STORAGE_NAME> with the name of the account you used in the previous step, and replace <APP_NAME> with a globally unique name appropriate to you. The <APP_NAME> is also the default DNS domain for the function app.

    This command creates a function app running in your specified language runtime under the Azure Functions Consumption Plan, which is free for the amount of usage you incur here. The command also provisions an associated Azure Application Insights instance in the same resource group, with which you can monitor your function app and view logs. For more information, see Monitor Azure Functions. The instance incurs no costs until you activate it.

[!INCLUDE functions-publish-project-cli]

[!INCLUDE functions-run-remote-azure-cli]

Run the following command to view near real-time streaming logs in Application Insights in the Azure portal:

func azure functionapp logstream <APP_NAME> --browser

In a separate terminal window or in the browser, call the remote function again. A verbose log of the function execution in Azure is shown in the terminal.

[!INCLUDE functions-cleanup-resources-cli]

Next steps

[!div class="nextstepaction"] Connect to an Azure Storage queue

Having issues? Let us know.