The Go runtime

Your Cloud Run function runs in an environment consisting of an operating system version with add-on packages, language support, and the Go 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 Go development, see Set up a Go development environment.

Supported Go runtimes and base images

Runtime	Runtime ID	Stacks	Runtime base image
Go 1.23	go123	google-22 (default) google-22-full	google-22/go123 google-22-full/go123
Go 1.22	go122	google-22 (default) google-22-full	google-22/go122 google-22-full/go122
Go 1.21	go121	google-22 (default) google-22-full	google-22/go121 google-22-full/go121
Go 1.20	go120	google-22 (default) google-22-full	google-22/go120 google-22-full/go120
Go 1.19	go119	google-22 (default) google-22-full	google-22/go119 google-22-full/go119
Go 1.18	go118	google-22 (default) google-22-full	google-22/go118 google-22-full/go120
Go 1.16	go116	google-18-full	google-18-full/go116
Go 1.13	go113	google-18-full	google-18-full/go113
Go 1.11	go111	Decommissioned	Decommissioned

Note: Go's release policy states that each major Go release is supported until there are two newer major releases. Thus, depending on when newer versions of Go are made publicly available, key dates such as end of support, deprecation, and decommission might be postponed.

Select your runtime

You can select one of the supported Go 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 Go 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 go123

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 Go 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.

Specify dependencies

Cloud Run functions in Go must provide all of their dependencies either with Go modules and a go.mod file, or with a vendor directory. For more information, see Specify dependencies in Go.

Environment variables

Your Go runtime automatically sets certain environment variables for your function to use as needed. For details, see Configure environment variables.

Context type

Go's context package defines the Context type, which carries deadlines, cancellation signals, and other request-scoped values across API boundaries and between processes.

The following code shows an example of context access by a Pub/Sub client:

// Package helloworld provides a set of Cloud Functions samples.
package helloworld

import (
	"context"
	"fmt"
	"log"

	"github.com/GoogleCloudPlatform/functions-framework-go/functions"
	"github.com/cloudevents/sdk-go/v2/event"
)

func init() {
	functions.CloudEvent("HelloPubSub", helloPubSub)
}

// MessagePublishedData contains the full Pub/Sub message
// See the documentation for more details:
// https://cloud.google.com/eventarc/docs/cloudevents#pubsub
type MessagePublishedData struct {
	Message PubSubMessage
}

// PubSubMessage is the payload of a Pub/Sub event.
// See the documentation for more details:
// https://cloud.google.com/pubsub/docs/reference/rest/v1/PubsubMessage
type PubSubMessage struct {
	Data []byte `json:"data"`
}

// helloPubSub consumes a CloudEvent message and extracts the Pub/Sub message.
func helloPubSub(ctx context.Context, e event.Event) error {
	var msg MessagePublishedData
	if err := e.DataAs(&msg); err != nil {
		return fmt.Errorf("event.DataAs: %w", err)
	}

	name := string(msg.Message.Data) // Automatically decoded from base64.
	if name == "" {
		name = "World"
	}
	log.Printf("Hello, %s!", name)
	return nil
}