Create and deploy an HTTP Cloud Function with .NET (1st gen)

Note: This content applies only to Cloud Functions (1st gen). See Create and deploy an HTTP Cloud Function with .NET (2nd gen) for the 2nd gen version of this document. See Cloud Functions version comparison for more information.

This guide takes you through the process of writing a Cloud Function using the .NET runtime language C#. There are two types of Cloud Functions:

• An HTTP-triggered function, which you invoke from standard HTTP requests.
• An event-driven function, which you use to handle events from your Cloud infrastructure, such as messages on a Pub/Sub topic, or changes in a Cloud Storage bucket.

Learn more: For more details, read about HTTP functions and event-driven functions.

Before you begin

1. Sign in to your Google Cloud account. If you're new to Google Cloud, create an account to evaluate how our products perform in real-world scenarios. New customers also get $300 in free credits to run, test, and deploy workloads.

2. In the Google Cloud console, on the project selector page, select or create a Google Cloud project.

   Note: If you don't plan to keep the resources that you create in this procedure, create a project instead of selecting an existing project. After you finish these steps, you can delete the project, removing all resources associated with the project.

   Go to project selector

3. Make sure that billing is enabled for your Google Cloud project.

4. Enable the Cloud Functions and Cloud Build APIs.

   Enable the APIs

5. In the Google Cloud console, on the project selector page, select or create a Google Cloud project.

   Note: If you don't plan to keep the resources that you create in this procedure, create a project instead of selecting an existing project. After you finish these steps, you can delete the project, removing all resources associated with the project.

   Go to project selector

6. Make sure that billing is enabled for your Google Cloud project.

7. Enable the Cloud Functions and Cloud Build APIs.

   Enable the APIs

8. Install and initialize the gcloud CLI.
9. Update and install gcloud components:

   gcloud components update

Note: Need a command prompt? You can use the Cloud Shell. The Cloud Shell is a command line environment that already includes the Google Cloud CLI, so you don't need to install it. The Google Cloud CLI also comes preinstalled on Google Compute Engine Virtual Machines.
10. Prepare your development environment.

    Go to the .NET setup guide

Create a function

This section describes how to manually create a function from scratch. Alternatively, you can use the templates provided by the template package.

To create a function:

1. Create a directory on your local system for the function code:

   Windows

   mkdir %HOMEPATH%\helloworld
   cd %HOMEPATH%\helloworld
   

   Linux or Mac OS X

   mkdir ~/helloworld
   cd ~/helloworld
   

2. Create a file called Function.cs with the contents below:

   using Google.Cloud.Functions.Framework;
   using Microsoft.AspNetCore.Http;
   using System.Threading.Tasks;
   
   namespace HelloWorld;
   
   public class Function : IHttpFunction
   {
       public async Task HandleAsync(HttpContext context)
       {
           await context.Response.WriteAsync("Hello World!", context.RequestAborted);
       }
   }

   This example function outputs the greeting "Hello World!"

Specify dependencies

The next step is to set up dependencies. There are two different types of dependencies you can set up in C# Cloud Functions:

• Make the Functions Framework available. That is the task you are doing in this section.
• Make other libraries available, both in terms of project files and within the code via dependency injection. To learn more, see Customization through Functions Startup classes.

To make the Functions Framework available, change directory to the helloworld directory you created above:

     cd ~/helloworld

Then create a file called HelloWorld.csproj with the contents below:

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net6.0</TargetFramework>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Google.Cloud.Functions.Hosting" Version="2.2.1" />
  </ItemGroup>
</Project>

Learn more: For more details, read about specifying dependencies.

Deploy the function

To deploy the function with an HTTP trigger, run the following command in the helloworld directory:

gcloud functions deploy my-first-function --entry-point HelloWorld.Function --runtime dotnet6 --trigger-http --allow-unauthenticated

where my-first-function is the registered name by which your function will be identified in the Google Cloud console, and --entry-point specifies your function's fully qualified class name (FQN).

Learn more: For more details, read about deploying Cloud Functions.

Test the deployed function

1. When the function finishes deploying, take note of the httpsTrigger.url property or find it using the following command:

   gcloud functions describe my-first-function
   

   It should look like this:

   https://GCP_REGION-PROJECT_ID.cloudfunctions.net/my-first-function

2. Visit this URL in your browser. You should see a Hello World! message.

Note: You can also find this URL in Google Cloud console. Go to the Cloud Functions Overview page, and click the name of your function to open its Function details page. Open the TRIGGER tab to see your function's URL.

View logs

Logs for Cloud Functions are viewable using the Google Cloud CLI, and in the Cloud Logging UI.

Use the command-line tool

To view logs for your function with the gcloud CLI, use the logs read command, followed by the name of the function:

gcloud functions logs read my-first-function

The output should resemble the following:

LEVEL  NAME               EXECUTION_ID  TIME_UTC                 LOG
D      my-first-function  k2bqgroszo4u  2020-07-24 18:18:01.791  Function execution started
D      my-first-function  k2bqgroszo4u  2020-07-24 18:18:01.958  Function execution took 168 ms, finished with status code: 200
...

Note: There is typically a slight delay between when log entries are created and when they show up in Cloud Logging.

Use the Logging dashboard

You can also view logs for Cloud Functions from the Google Cloud console.

Learn more: For more details, read about writing, viewing, and responding to logs.

Use the template package

The sections above tell you how to manually create a function from scratch. Going forward, you will likely use the templates to create new functions.

To use the templates to create, build, and test a function:

1. Install the .NET SDK.

2. Install the template package:

   dotnet new install Google.Cloud.Functions.Templates
   

   Note: versions of the .NET SDK earlier than .NET 7 use dotnet new -i instead of dotnet new install.

3. Next, create a directory for your project, and use dotnet new to create a new HTTP function:

   mkdir HelloFunctions
   cd HelloFunctions
   dotnet new gcf-http
   

   This creates HelloFunctions.csproj and Function.cs in the current directory. Open Function.cs to review the code, and provide a custom message if you want.

   Note: To learn how to use the templates to create F# and Visual Basic functions, see .NET Languages.

4. Build your function locally as follows:

   dotnet run
   

5. Once the server is running, browse to http://localhost:8080 to invoke the function. Press Ctrl-C in the console to stop the server.

   This function displays the message "Hello Functions Framework."

Alternatively, you can send requests to this function using curl from another terminal window:

curl localhost:8080
# Output: Hello Functions Framework