Write Cloud Run functions

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This page provides an introduction for writing Cloud Run functions with the Functions Framework.

When writing functions source code, you must use the Functions Framework, an open source library for writing Cloud Run functions. With the Functions Framework, you can write lightweight functions that run in Cloud Run and in other environments, including your local development machine and Knative-based environments.

The Functions Framework lets you:

• Invoke a Cloud Run function in response to a request.
• Automatically unmarshal events conforming to the CloudEvents spec, an industry-standard specification for describing event data in a common way.
• Start a local development server for quick testing.

Write functions with the Functions Framework

The Functions Framework provides an interface for building modular services. To use the Functions Framework in your source code, specify the following:

• Entry point
• Signature type

Function entry point

Your source code must define an entry point for your function, which is the particular code executed when the Cloud Run function is invoked. You specify this entry point when you deploy your function.

How you define the entry point depends on the language runtime you use. Some languages use a function as their entry point, while others use a class.

Signature Type

When you write the source code of a function with the Functions Framework, you must specify one of the two signature types:

• HTTP functions: A function that registers an HTTP handler function. See Write HTTP functions for more information.
• Event-driven functions (also called CloudEvents functions): A function that registers a CloudEvents handler function. See Write event-driven functions for more information.

Use an HTTP function when you need your function to have a URL endpoint and respond to HTTP requests, such as for webhooks. Use an event-driven function when your function should be triggered directly in response to events within your Google Cloud project, such as messages on a Pub/Sub topic or changes in a Cloud Storage bucket.

Source directory structure

The Functions Framework is supported in a number of programming languages. The language runtime you choose and the type of function you want to write determines how to structure your code and implement your function.

For Cloud Run to locate your function definition, each language runtime has requirements for structuring your source code.

.
├── index.js
└── package.json

{
  "main": "index.js",
  "dependencies": {
    "@google-cloud/functions-framework": "^3.0.0"
  }
}

.
├── main.py
└── requirements.txt

functions-framework==3.*

.
├── myfunction.go
└── go.mod

.
├── myfunction.go
├── go.mod
└── cmd/
  └── main.go

module example.com/my-module

require (
  github.com/GoogleCloudPlatform/functions-framework-go v1.5.2
)

.
├── pom.xml
└── src/
  └── main/
      └── java/
          └── MyFunction.java

.
├── pom.xml
└── src/
  └── main/
      └── java/
          └── mypackage/
              └── MyFunction.java

...
    <dependency>
      <groupId>com.google.cloud.functions</groupId>
      <artifactId>functions-framework-api</artifactId>
      <version>1.0.4</version>
    </dependency>
...

.
├── MyFunction.cs
└── MyProject.csproj

...
    <PackageReference Include="Google.Cloud.Functions.Hosting" Version="1.0.0" />
...

.
├── app.rb
├── Gemfile
└── Gemfile.lock

source "https://rubygems.org"
gem "functions_framework", "~> 1.0"

.
├── index.php
└── composer.json

{
  "require": {
    "google/cloud-functions-framework": "^1.1"
  }
}

If you group multiple functions into a single project, be aware that every function might end up sharing the same set of dependencies. However, some of the functions might not need all of the dependencies.

Where possible, we recommend splitting up large multi-function codebases and putting each function in its own top-level directory as shown in the preceding examples, with its own source and project configuration files. This approach minimizes the number of dependencies required for a particular function, which in turn reduces the amount of memory your function needs.

Use Gemini Code Assist for code completions

If you have set up Gemini Code Assist, you can use the code completion feature when writing functions. As you type, Gemini makes code suggestions relevant to your current context.

Required roles

To get the permission that you need to complete code with Gemini Code Assist in Cloud Run functions, ask your administrator to grant you the Cloud AI Companion User (roles/cloudaicompanion.user) IAM role on your project. For more information about granting roles, see Manage access to projects, folders, and organizations.

This predefined role contains the cloudaicompanion.instances.completeCode permission, which is required to complete code with Gemini Code Assist in Cloud Run functions.

You might also be able to get this permission with custom roles or other predefined roles.

Try Gemini Code Assist code completions

To try Gemini Code Assist code completions, follow these steps:

1. Set up your Cloud Run development environment in your Google Cloud project.
2. Ensure you have the appropriate permissions to deploy functions.
3. Ensure that Gemini Code Assist is set up for your Google Cloud user account and project.

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

   Go to Cloud Run

5. Begin configuring the Cloud Run function. If you are creating a new function, click Write a function. If you are configuring an existing function, click Services, select Filter services > Deployment type > Function, and click the function.

6. Open the Source tab to edit your code with the text editor.

   

7. In the toolbar, click pen_spark Gemini, then select Code completion if it isn't already selected.

   

8. To try code completions, type code in the editor.

   For example, if you want to add an HTTP function using the Function Framework for Node.js, start typing functions.https. In response, Gemini generates Node.js code that's similar to the following:

   functions.https('helloHttps', (req, res) => {
     res.send(`Hello ${req.query.name || req.body.name || 'World'}!`);
   

9. Review the generated code and take any of the following actions:

   • To accept a suggestion by Gemini, press Tab.
   • To accept the next word, press Control+Right Arrow (Command+Right Arrow on macOS).
   • To dismiss a suggestion, press Esc or continue typing.

For more details about Gemini, see the following resources:

• Gemini for Google Cloud overview
• How Gemini uses your data
• Gemini for Google Cloud and responsible AI

What's next

• Implement HTTP functions
• Implement event-driven functions
• Learn about the Functions Framework Contract