The .NET runtime

Your Cloud Run function runs in an environment consisting of an operating system version with add-on packages, language support, and the .NET Functions Framework library that supports and invokes your function. This environment is identified by the language version, and is known as the runtime ID.

Function preparation

You can prepare a function directly from the Google Cloud console or write it on your local machine and upload it. To prepare your local machine for .NET development, see Set up a .NET development environment.

Supported .NET runtimes and base images

Runtime	Runtime ID	Stacks	Runtime base image
.NET 8	dotnet8	google-22 (default) google-22-full	google-22/dotnet8 google-22-full/dotnet8
.NET 6	dotnet6	google-22 (default) google-22-full	google-22/dotnet6 google-22-full/dotnet6
.NET Core 3	dotnet3	google-18-full	google-18-full/dotnet3

Template package

The template package helps you to create new functions. To use it:

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.

Templates are provided for the three kinds of functions in C# (the default), F#, and Visual Basic. When creating a new project from a template, specify -lang f# to create an F# project, or -lang vb to create a Visual Basic project.

Select your runtime

When you deploy your function, you must specify a .NET runtime corresponding to the target framework in your project file (MyFunction.csproj or similar). You can select one of the supported .NET runtimes for your function during deployment.

You can select a runtime version using the Google Cloud console, or the gcloud CLI. Click the tab for instructions on using the tool of your choice:

gcloud

Specify the .NET base image for your function using the --base-image flag, while deploying your function. For example:

gcloud run deploy FUNCTION \
    --source . \
    --function FUNCTION_ENTRYPOINT \
    --base-image dotnet8

Replace:

• FUNCTION with the name of the function you are deploying. You can omit this parameter entirely, but you will be prompted for the name if you omit it.

• FUNCTION_ENTRYPOINT with the entry point to your function in your source code. This is the code Cloud Run executes when your function runs. The value of this flag must be a function name or fully-qualified class name that exists in your source code.

For detailed instructions on deploying a function using the gcloud CLI, see Deploy functions in Cloud Run.

Console

You can select a runtime version when you create or update a Cloud Run function in the Google Cloud console. For detailed instructions on deploying a function, see Deploy functions in Cloud Run.

To select a runtime in the Google Cloud console when you create a function, follow these steps:

1. In the Google Cloud console, go to the Cloud Run page:

   Go to Cloud Run

2. Click Write a function.

3. In the Runtime list, select a .NET runtime version.

4. Click Create, and wait for Cloud Run to create the service using a placeholder revision.

5. The console will redirect you to the Source tab where you can see the source code of your function. Click Save and redeploy.

For detailed instructions on updating the runtime version after your function is deployed, see Re-deploy new source code.

Source code structure

For Cloud Run functions to find your function's definition, your source code must follow a specific structure. See Write Cloud Run functions for more information.

Specifying dependencies

.NET Cloud Run functions uses Microsoft Build Engine (MSBuild) project files which are central to the build and deployment process. You can specify dependencies for your function in a project file. For C# the file extension is .csproj, for F# it is .fsproj, and for Visual Basic it is .vbproj.

For more discussion of dependencies and other types of customization, see Customization through Functions Startup classes.