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title description ms.date ms.topic ms.custom adobe-target adobe-target-activity adobe-target-experience adobe-target-content
Create a C# function from the command line - Azure Functions
Learn how to create a C# function from the command line, then publish the local project to serverless hosting in Azure Functions.
09/14/2021
quickstart
devx-track-csharp
devx-track-azurecli
devx-track-azurepowershell
true
DocsExp–386541–A/B–Enhanced-Readability-Quickstarts–2.19.2021
Experience B
./create-first-function-cli-csharp-ieux

Quickstart: Create a C# function in Azure from the command line

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

[!INCLUDE functions-dotnet-execution-model]

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:

In-process

Isolated process

You also need an Azure account with an active subscription. Create an account for free.

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 dotnet --list-sdks to check that the required versions are installed.

  • 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.

Azure PowerShell

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

  • Run dotnet --list-sdks to check that the required versions are installed.

  • 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.

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:

    In-process

    func init LocalFunctionProj --dotnet

    Isolated process

    func init LocalFunctionProj --worker-runtime dotnet-isolated

  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 HttpExample.cs code file.

(Optional) Examine the file contents

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

HttpExample.cs

The function code generated from the template depends on the type of compiled C# project.

In-process

HttpExample.cs contains a Run method that receives request data in the req variable is an HttpRequest that's decorated with the HttpTriggerAttribute, which defines the trigger behavior.

:::code language="csharp" source="~/functions-docs-csharp/http-trigger-template/HttpExample.cs":::

The return object is an ActionResult that returns a response message as either an OkObjectResult (200) or a BadRequestObjectResult (400).

Isolated process

HttpExample.cs contains a Run method that receives request data in the req variable is an HttpRequestData object that's decorated with the HttpTriggerAttribute, which defines the trigger behavior. Because of the isolated process model, HttpRequestData is a representation of the actual HttpRequest, and not the request object itself.

:::code language="csharp" source="~/functions-docs-csharp/http-trigger-isolated/HttpExample.cs":::

The return object is an HttpResponseData object that contains the data that's handed back to the HTTP response.

To learn more, see Azure Functions HTTP triggers and bindings.

Run the function locally

  1. Run your function by starting the local Azure Functions runtime host from the LocalFunctionProj folder:

    func start

    Toward the end of the output, the following lines should appear:

     ...

 Now listening on: http://0.0.0.0:7071
 Application started. Press Ctrl+C to shut down.

 Http Functions:

         HttpExample: [GET,POST] http://localhost:7071/api/HttpExample
 ...

    [!NOTE] If HttpExample doesn't appear as shown above, you likely started the host from outside the root folder of the project. In that case, use Ctrl+C to stop the host, navigate to the project's root folder, and run the previous command again.

  2. Copy the URL of your HttpExample function from this output to a browser:

    In-process

    To the function URL, append the query string ?name=<YOUR_NAME>, making the full URL like http://localhost:7071/api/HttpExample?name=Functions. The browser should display a response message that echoes back your query string value. The terminal in which you started your project also shows log output as you make requests.

    Isolated process

    Browse to the function URL and you should receive a Welcome to Azure Functions message.

  3. When you're done, use Ctrl+C and choose y to stop the functions host.

[!INCLUDE functions-create-azure-resources-cli]

  1. Create the function app in Azure:

    Azure CLI

    az functionapp create --resource-group AzureFunctionsQuickstart-rg --consumption-plan-location <REGION> --runtime dotnet --functions-version 3 --name <APP_NAME> --storage-account <STORAGE_NAME>

    The az functionapp create command creates the function app in Azure.

    Azure CLI

    az functionapp create --resource-group AzureFunctionsQuickstart-rg --consumption-plan-location <REGION> --runtime dotnet-isolated --functions-version 3 --name <APP_NAME> --storage-account <STORAGE_NAME>

    The az functionapp create command creates the function app in Azure.

    Azure PowerShell

    New-AzFunctionApp -Name <APP_NAME> -ResourceGroupName AzureFunctionsQuickstart-rg -StorageAccount <STORAGE_NAME> -Runtime dotnet -FunctionsVersion 3 -Location '<REGION>'

    The New-AzFunctionApp cmdlet creates the function app in Azure.

    Azure PowerShell

    New-AzFunctionApp -Name <APP_NAME> -ResourceGroupName AzureFunctionsQuickstart-rg -StorageAccount <STORAGE_NAME> -Runtime dotnet-isolated -FunctionsVersion 3 -Location '<REGION>'

    The New-AzFunctionApp cmdlet creates the function app in Azure.

    [!NOTE] This command creates a function app using the 3.x version of the Azure Functions runtime. The func azure functionapp publish command that you'll run later updates the app to version 4.x.

    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]

Invoke the function on Azure

Because your function uses an HTTP trigger and supports GET requests, you invoke it by making an HTTP request to its URL. It's easiest to do this in a browser.

In-process

Copy the complete Invoke URL shown in the output of the publish command into a browser address bar, appending the query parameter ?name=Functions. When you navigate to this URL, the browser should display similar output as when you ran the function locally.

Isolated process

Copy the complete Invoke URL shown in the output of the publish command into a browser address bar. When you navigate to this URL, the browser should display similar output as when you ran the function locally.

[!INCLUDE functions-streaming-logs-cli-qs]

[!INCLUDE functions-cleanup-resources-cli]

Next steps

In-process

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

Isolated process

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