# Serverless Workers on GCP Cloud Run - Go SDK

> Run a Temporal Worker on a GCP Cloud Run worker pool using the Go SDK.

> **Pre-release**
> Cloud Run support is in Pre-release, and its APIs may change in backwards-incompatible ways.
> Create a [support ticket](/cloud/support#support-ticket) or contact your account team for access, and
> [sign up for updates](https://temporal.io/pages/serverless-workers-updates) to hear when Cloud Run reaches Public Preview.

On a [GCP Cloud Run worker pool](https://cloud.google.com/run/docs/resource-model#worker-pools), you run a standard long-lived Temporal Worker.
Register Workflows and Activities the same way you would with any other Go Worker, and Temporal Cloud scales the pool up and down as work arrives and drains.

A Cloud Run Worker needs no Cloud Run-specific package.
The one addition to a standard Worker is Worker Versioning, which is required for Serverless Workers.

For the end-to-end deployment guide covering the Worker Pool, IAM, and compute configuration, see [Deploy a Serverless Worker on GCP Cloud Run](/production-deployment/worker-deployments/serverless-workers/cloud-run).

## Create a versioned Worker 

Build the Worker as you would any long-running Go Worker, then set `DeploymentOptions` in [`worker.Options`](https://pkg.go.dev/go.temporal.io/sdk/internal#WorkerOptions) to declare the Worker Deployment Version and turn versioning on.

The following Worker reads its connection settings and Task Queue from the environment, so the same image can run against any Namespace:

```go
package main

import (
	"log"
	"os"

	"go.temporal.io/sdk/client"
	"go.temporal.io/sdk/contrib/envconfig"
	"go.temporal.io/sdk/worker"
	"go.temporal.io/sdk/workflow"

	"example.com/myapp"
)

func main() {
	c, err := client.Dial(envconfig.MustLoadDefaultClientOptions())
	if err != nil {
		log.Fatalln("Unable to create client", err)
	}
	defer c.Close()

	w := worker.New(c, os.Getenv("TEMPORAL_TASK_QUEUE"), worker.Options{
		DeploymentOptions: worker.DeploymentOptions{
			UseVersioning: true,
			Version: worker.WorkerDeploymentVersion{
				DeploymentName: "my-app",
				BuildID:        "build-1",
			},
		},
	})

	w.RegisterWorkflowWithOptions(myapp.MyWorkflow, workflow.RegisterOptions{
		VersioningBehavior: workflow.VersioningBehaviorPinned,
	})
	w.RegisterActivity(myapp.MyActivity)

	if err := w.Run(worker.InterruptCh()); err != nil {
		log.Fatalln("Unable to start worker", err)
	}
}
```

`DeploymentName` and `BuildID` together identify the Worker Deployment Version. Both values must match the version you create with `temporal worker deployment create-version` in the deployment guide, or the Worker polls under a version the WCI does not manage.

Every Workflow needs a [versioning behavior](/worker-versioning#versioning-behaviors), either `VersioningBehaviorPinned` or `VersioningBehaviorAutoUpgrade`.
Set it per Workflow at registration as shown above, or set `DefaultVersioningBehavior` in `DeploymentOptions` to cover every Workflow on the Worker.
If a Version is set and neither is specified, registration panics with `workflow type does not have a versioning behavior`.

For general Worker setup and options that are not specific to Cloud Run, see [Run a Worker](/develop/go/workers/run-worker-process).

## Configure the Temporal connection 

The `envconfig` package loads Temporal Client configuration from environment variables and an optional TOML config file, so the Worker code carries no Namespace or credentials.
Set the non-secret values as environment variables on the Worker Pool, and mount the Temporal Cloud API key or TLS material from Secret Manager.
For the full list of supported variables, the config file format, and profiles, see [Environment configuration](/develop/environment-configuration).

`MustLoadDefaultClientOptions` panics if the configuration is invalid. To handle a bad configuration yourself, use `envconfig.LoadDefaultClientOptions` and check the returned error.

## Keep Activities safe across scale-in 

The WCI decides when to remove an instance from Task Queue activity, not from what an individual instance is doing.
An instance running a long Activity can be stopped mid-execution.

Use [Activity Heartbeats](/develop/go/activities/timeouts#activity-heartbeats) so a retry resumes from the last recorded progress instead of starting over:

```go
func MyActivity(ctx context.Context, input MyInput) (string, error) {
	for i := range input.Items {
		activity.RecordHeartbeat(ctx, i)
		// ... process input.Items[i]
	}
	return "done", nil
}
```

For how scale-in decisions are made, see [Serverless Workers on GCP Cloud Run](/serverless-workers/cloud-run#lifecycle).

## Add observability 

A Cloud Run Worker emits the same traces and metrics as a Worker anywhere else.
For how to configure metrics export and OpenTelemetry tracing interceptors, see [Observability - Go SDK](/develop/go/platform/observability) and the [SDK metrics reference](/references/sdk-metrics).