Standalone Activities - Go SDK

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Currently in: Public Preview

APIs and configuration may change before the stable release.

Standalone Activities are Activity Executions that run independently, without being orchestrated by a Workflow. Instead of starting an Activity from within a Workflow Definition using workflow.ExecuteActivity(), you start a Standalone Activity directly from a Temporal Client using client.ExecuteActivity().

The Activity definition and Worker registration are identical to regular Activities, and only the execution path differs.

This page covers the following:

• Get Started with Standalone Activities
• Define your Activity
• Run a Worker with the Activity registered
• Execute a Standalone Activity
• Get the result of a Standalone Activity
• Get a handle to an existing Standalone Activity
• List Standalone Activities
• Count Standalone Activities
• Run Standalone Activities with Temporal Cloud
• Move to production with Serverless Workers

info

This documentation uses source code from the standalone-activity/helloworld.

Get Started with Standalone Activities

Prerequisites:

• Go 1.22+

• Temporal Go SDK (v1.41.0 or higher)

• Temporal CLI v1.7.0 or higher

  Install with Homebrew:

  brew install temporal

  Or see the Temporal CLI install guide for other platforms.

  Verify the installation:

  temporal --version

Start the Temporal development server:

temporal server start-dev

This command automatically starts the Temporal development server with the Web UI, and creates the default Namespace. It uses an in-memory database, so do not use it for real use cases.

Temporal Cloud

All code samples on this page use envconfig.MustLoadDefaultClientOptions() to configure the Temporal Client connection. It responds to environment variables and TOML configuration files, so the same code works against a local dev server and Temporal Cloud without changes. See Run Standalone Activities with Temporal Cloud below.

The Temporal Server should now be available for client connections on localhost:7233, and the Temporal Web UI should now be accessible at http://localhost:8233. Standalone Activities are available from the nav bar item located towards the top left of the page:

Clone the samples-go repository to follow along:

git clone https://github.com/temporalio/samples-go.git
cd samples-go

The sample project is structured as follows:

standalone-activity/helloworld/
├── activity.go
├── worker/
│   └── main.go
└── starter/
    └── main.go

Define your Activity

Define your Activity in a shared file so that both the Worker and starter can reference it.

standalone-activity/helloworld/activity.go

package helloworld

import (
	"context"
	"go.temporal.io/sdk/activity"
)

func Activity(ctx context.Context, name string) (string, error) {
	logger := activity.GetLogger(ctx)
	logger.Info("Activity", "name", name)
	return "Hello " + name + "!", nil
}

Run a Worker with the Activity registered

Running a Worker for Standalone Activities is the same as running a Worker for Workflow-driven Activities — you create a Worker, register the Activity, and call Run(). The Worker doesn't need to know whether the Activity will be invoked from a Workflow or as a Standalone Activity.

See How to develop a Worker in Go for more details on Worker setup and configuration options.

standalone-activity/helloworld/worker/main.go

package main

import (
	"github.com/temporalio/samples-go/standalone-activity/helloworld"
	"go.temporal.io/sdk/client"
	"go.temporal.io/sdk/contrib/envconfig"
	"go.temporal.io/sdk/worker"
	"log"
)

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, "standalone-activity-helloworld", worker.Options{})

	w.RegisterActivity(helloworld.Activity)

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

Open a new terminal, navigate to the samples-go directory, and run the Worker:

go run standalone-activity/helloworld/worker/main.go

Leave this terminal running - the Worker needs to stay up to process activities.

Execute a Standalone Activity

Use client.ExecuteActivity() to start a Standalone Activity Execution. This is called from application code (for example, a starter program), not from inside a Workflow Definition.

ExecuteActivity returns an ActivityHandle that you can use to get the result, describe, cancel, or terminate the Activity.

The following starter program demonstrates how to execute a Standalone Activity, get its result, list activities, and count activities:

standalone-activity/helloworld/starter/main.go

package main

import (
	"context"
	"github.com/temporalio/samples-go/standalone-activity/helloworld"
	"go.temporal.io/sdk/client"
	"go.temporal.io/sdk/contrib/envconfig"
	"log"
	"time"
)

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

	activityOptions := client.StartActivityOptions{
		ID:        "standalone_activity_helloworld_ActivityID",
		TaskQueue: "standalone-activity-helloworld",
		ScheduleToCloseTimeout: 10 * time.Second,
	}

	handle, err := c.ExecuteActivity(context.Background(), activityOptions, helloworld.Activity, "Temporal")
	if err != nil {
		log.Fatalln("Unable to execute activity", err)
	}

	log.Println("Started standalone activity", "ActivityID", handle.GetID(), "RunID", handle.GetRunID())

	var result string
	err = handle.Get(context.Background(), &result)
	if err != nil {
		log.Fatalln("Unable get standalone activity result", err)
	}
	log.Println("Activity result:", result)

	resp, err := c.ListActivities(context.Background(), client.ListActivitiesOptions{
		Query: "TaskQueue = 'standalone-activity-helloworld'",
	})
	if err != nil {
		log.Fatalln("Unable to list activities", err)
	}

	log.Println("ListActivity results")
	for info, err := range resp.Results {
		if err != nil {
			log.Fatalln("Error iterating activities", err)
		}
		log.Printf("\tActivityID: %s, Type: %s, Status: %v\n",
			info.ActivityID, info.ActivityType, info.Status)
	}

	resp1, err := c.CountActivities(context.Background(), client.CountActivitiesOptions{
		Query: "TaskQueue = 'standalone-activity-helloworld'",
	})
	if err != nil {
		log.Fatalln("Unable to count activities", err)
	}

	log.Println("Total activities:", resp1.Count)
}

You can pass the Activity as either a function reference or a string Activity type name:

handle, err := c.ExecuteActivity(ctx, options, helloworld.Activity, "arg1")

// Using a string type name
handle, err := c.ExecuteActivity(ctx, options, "Activity", "arg1")

client.StartActivityOptions requires ID, TaskQueue, and at least one of ScheduleToCloseTimeout or StartToCloseTimeout. See StartActivityOptions in the API reference for the full set of options.

To run the starter:

1. Make sure the Temporal Server is running (from the Get Started step above).
2. Make sure the Worker is running (from the Run a Worker step above).
3. Open a new terminal, navigate to the samples-go directory, and run:

go run standalone-activity/helloworld/starter/main.go

Or use the Temporal CLI to execute a Standalone Activity:

temporal activity execute \
  --type Activity \
  --activity-id standalone_activity_helloworld_ActivityID \
  --task-queue standalone-activity-helloworld \
  --schedule-to-close-timeout 10s \
  --input '"Temporal"'

Get the result of a Standalone Activity

Use ActivityHandle.Get() to block until the Activity completes and retrieve its result. This is analogous to calling Get() on a WorkflowRun.

var result string
err = handle.Get(context.Background(), &result)
if err != nil {
	log.Fatalln("Activity failed", err)
}
log.Println("Activity result:", result)

If the Activity completed successfully, the result is deserialized into the provided pointer. If the Activity failed, the failure is returned as an error.

Or use the Temporal CLI to wait for a result by Activity ID:

temporal activity result --activity-id standalone_activity_helloworld_ActivityID

Get a handle to an existing Standalone Activity

Use client.GetActivityHandle() to create a handle to a previously started Standalone Activity. This is analogous to client.GetWorkflow() for Workflow Executions.

Both ActivityID and RunID are required.

handle := c.GetActivityHandle(client.GetActivityHandleOptions{
	ActivityID: "standalone_activity_helloworld_ActivityID",
	RunID:      "the-run-id",
})

// Use the handle to get the result, describe, cancel, or terminate
var result string
err := handle.Get(context.Background(), &result)
if err != nil {
	log.Fatalln("Unable to get activity result", err)
}

List Standalone Activities

Use client.ListActivities() to list Standalone Activity Executions that match a List Filter query. The result contains an iterator that yields ActivityExecutionInfo entries.

These APIs return only Standalone Activity Executions. Activities running inside Workflows are not included.

resp, err := c.ListActivities(context.Background(), client.ListActivitiesOptions{
	Query: "TaskQueue = 'standalone-activity-helloworld'",
})
if err != nil {
	log.Fatalln("Unable to list activities", err)
}

for info, err := range resp.Results {
	if err != nil {
		log.Fatalln("Error iterating activities", err)
	}
	log.Printf("ActivityID: %s, Type: %s, Status: %v\n",
		info.ActivityID, info.ActivityType, info.Status)
}

Or use the Temporal CLI:

temporal activity list

The Query field accepts the same List Filter syntax used for Workflow Visibility. For example, "ActivityType = 'Activity' AND Status = 'Running'".

Count Standalone Activities

Use client.CountActivities() to count Standalone Activity Executions that match a List Filter query. This returns the total count of executions (running, completed, failed, etc.) - not the number of queued tasks. It works the same way as counting Workflow Executions.

resp, err := c.CountActivities(context.Background(), client.CountActivitiesOptions{
	Query: "TaskQueue = 'standalone-activity-helloworld'",
})
if err != nil {
	log.Fatalln("Unable to count activities", err)
}

log.Println("Total activities:", resp.Count)

Or use the Temporal CLI:

temporal activity count

Run Standalone Activities with Temporal Cloud

The code samples on this page use envconfig.MustLoadDefaultClientOptions(), so the same code works against Temporal Cloud - just configure the connection via environment variables or a TOML profile. No code changes are needed.

For a step-by-step guide on connecting to Temporal Cloud, including Namespace creation, certificate generation, and authentication setup in the Cloud UI, see Connect to Temporal Cloud.

Connect with mTLS

Set these environment variables with values from your Temporal Cloud Namespace settings:

export TEMPORAL_ADDRESS=<your-namespace>.<your-account-id>.tmprl.cloud:7233
export TEMPORAL_NAMESPACE=<your-namespace>.<your-account-id>
export TEMPORAL_TLS_CLIENT_CERT_PATH='path/to/your/client.pem'
export TEMPORAL_TLS_CLIENT_KEY_PATH='path/to/your/client.key'

Connect with an API key

Set these environment variables with values from your Temporal Cloud API key settings:

export TEMPORAL_ADDRESS=<your-namespace>.<your-account-id>.tmprl.cloud:7233
export TEMPORAL_NAMESPACE=<your-namespace>.<your-account-id>
export TEMPORAL_API_KEY=<your-api-key>

Then run the Worker and starter code as shown in the earlier sections.

Move to production with Serverless Workers

After you have run the Standalone Activity locally and configured its Temporal Cloud connection, you can deploy its Worker as a Serverless Worker. Serverless Workers run on ephemeral, on-demand compute rather than as long-lived processes.

info

Serverless Workers are a separate Pre-release feature. To request access, create a support ticket or contact your account team.

AWS Lambda

AWS Lambda is the first Serverless Worker provider example. When a Standalone Activity Task is added to a Task Queue with no active poller, Temporal invokes the Lambda function configured for that Task Queue. The Worker connects, processes available Tasks, and shuts down before the Lambda invocation deadline.

The Standalone Activity Lambda sample contains an Activity, an activity-only Lambda Worker, and a starter program:

standalone-activity/lambda-worker/
├── activity.go
├── worker/
│   └── main.go
└── starter/
    └── main.go

Register the Activity with a Lambda Worker

Use the Go SDK's lambdaworker package to run the Worker inside Lambda. Set the Worker Deployment name, Build ID, and Task Queue, then register the Activity.

standalone-activity/lambda-worker/worker/main.go

package main

import (
	lambdaworker "go.temporal.io/sdk/contrib/aws/lambdaworker"
	"go.temporal.io/sdk/worker"

	lambdaactivity "github.com/temporalio/samples-go/standalone-activity/lambda-worker"
)

func main() {
	lambdaworker.RunWorker(worker.WorkerDeploymentVersion{
		DeploymentName: "standalone-activity-lambda",
		BuildID:        "build-1",
	}, func(options *lambdaworker.Options) error {
		options.TaskQueue = "standalone-activity-lambda"
		options.RegisterActivity(lambdaactivity.Greet)
		return nil
	})
}

An activity-only Worker doesn't register a Workflow, so it doesn't need to set a Workflow versioning behavior. The WorkerDeploymentVersion is still required because Serverless Workers use Worker Deployment Versioning to route Tasks to the configured Lambda function.

Deploy the Worker to Lambda

Follow Deploy a Serverless Worker on AWS Lambda to build and package the Worker, create the Lambda function, configure IAM, and create the Worker Deployment Version.

Run the guide's build commands from standalone-activity/lambda-worker so ./worker resolves to the sample's Worker package. Use these values when you configure the Worker Deployment Version:

Setting	Value
Worker Deployment name	standalone-activity-lambda
Build ID	build-1
Task Queue	standalone-activity-lambda

The Worker Deployment name and Build ID must match the values passed to lambdaworker.RunWorker. After you create the version, set it as current so Temporal can route Tasks to it.

Execute the Standalone Activity

Run the starter outside Lambda. It connects to Temporal and schedules the Standalone Activity on the same Task Queue as the Serverless Worker.

standalone-activity/lambda-worker/starter/main.go

package main

import (
	"context"
	"log"
	"time"

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

	lambdaactivity "github.com/temporalio/samples-go/standalone-activity/lambda-worker"
)

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

	handle, err := temporalClient.ExecuteActivity(
		context.Background(),
		client.StartActivityOptions{
			ID:                     "standalone-activity-lambda-greeting",
			TaskQueue:              "standalone-activity-lambda",
			ScheduleToCloseTimeout: time.Minute,
		},
		lambdaactivity.Greet,
		"Temporal",
	)
	if err != nil {
		log.Fatalln("Unable to execute Standalone Activity", err)
	}

	var result string
	if err := handle.Get(context.Background(), &result); err != nil {
		log.Fatalln("Standalone Activity failed", err)
	}
	log.Println("Standalone Activity result:", result)
}

Configure the starter's Temporal Client connection using environment configuration, then run it from the sample directory:

go run ./starter

When the starter schedules the Activity, Temporal invokes the Lambda function, and the Lambda Worker processes the Activity Task and returns the result.