CLI quick start

Note

Workflows is in public beta, and any developer with a free or paid Workers plan can start using Workflows immediately.

To learn more about Workflows and how it works, read the beta announcement blog ↗.

Workflows allow you to build durable, multi-step applications using the Workers platform. A Workflow can automatically retry, persist state, run for hours or days, and coordinate between third-party APIs.

You can build Workflows to post-process file uploads to R2 object storage, automate generation of Workers AI embeddings into a Vectorize vector database, or to trigger user lifecycle emails using your favorite email API.

Prerequisites

Warning

This guide is for users who are already familiar with Cloudflare Workers the durable execution programming model it enables.

If you are new to either, we recommend the introduction to Workflows guide, which walks you through how a Workflow is defined, how to persist state, and how to deploy and run your first Workflow.

1. Sign up for a Cloudflare account ↗.
2. Install Node.js ↗.

Node.js version manager

Use a Node version manager like Volta ↗ or nvm ↗ to avoid permission issues and change Node.js versions. Wrangler, discussed later in this guide, requires a Node version of 16.17.0 or later.

1. Create a Workflow

Workflows are defined as part of a Worker script.

To create a Workflow, use the create cloudflare (C3) CLI tool, specifying the Workflows starter template:

npm create cloudflare@latest workflows-starter -- --template "cloudflare/workflows-starter"

This will create a new folder called workflows-tutorial, which contains two files:

• src/index.ts - this is where your Worker script, including your Workflows definition, is defined.
• wrangler.toml - the configuration for your Workers project and your Workflow.

Open the src/index.ts file in your text editor. This file contains the following code, which is the most basic instance of a Workflow definition:

src/index.ts

import { WorkflowEntrypoint, WorkflowStep, WorkflowEvent } from 'cloudflare:workers';

type Env = {
  // Add your bindings here, e.g. Workers KV, D1, Workers AI, etc.
  MY_WORKFLOW: Workflow;
};

// User-defined params passed to your workflow
type Params = {
  email: string;
  metadata: Record<string, string>;
};

export class MyWorkflow extends WorkflowEntrypoint<Env, Params> {
  async run(event: WorkflowEvent<Params>, step: WorkflowStep) {
    // Can access bindings on `this.env`
    // Can access params on `event.params`

    const files = await step.do('my first step', async () => {
      // Fetch a list of files from $SOME_SERVICE
      return {
        inputParams: event,
        files: [
          'doc_7392_rev3.pdf',
          'report_x29_final.pdf',
          'memo_2024_05_12.pdf',
          'file_089_update.pdf',
          'proj_alpha_v2.pdf',
          'data_analysis_q2.pdf',
          'notes_meeting_52.pdf',
          'summary_fy24_draft.pdf',
        ],
      };
    });

    const apiResponse = await step.do('some other step', async () => {
      let resp = await fetch('https://api.cloudflare.com/client/v4/ips');
      return await resp.json<any>();
    });

    await step.sleep('wait on something', '1 minute');

    await step.do(
      'make a call to write that could maybe, just might, fail',
      // Define a retry strategy
      {
        retries: {
          limit: 5,
          delay: '5 second',
          backoff: 'exponential',
        },
        timeout: '15 minutes',
      },
      async () => {
        // Do stuff here, with access to the state from our previous steps
        if (Math.random() > 0.5) {
          throw new Error('API call to $STORAGE_SYSTEM failed');
        }
      },
    );
  }
}

export default {
  async fetch(req: Request, env: Env): Promise<Response> {
    let id = new URL(req.url).searchParams.get('instanceId');

    // Get the status of an existing instance, if provided
    if (id) {
      let instance = await env.MY_WORKFLOW.get(id);
      return Response.json({
        status: await instance.status(),
      });
    }

    // Spawn a new instance and return the ID and status
    let instance = await env.MY_WORKFLOW.create();
    return Response.json({
      id: instance.id,
      details: await instance.status(),
    });
  },
};

Specifically, the code above:

1. Extends the Workflows base class (WorkflowsEntrypoint) and defines a run method for our Workflow.
2. Passes in our Params type as a type parameter so that events that trigger our Workflow are typed.
3. Defines several steps that return state.
4. Defines a custom retry configuration for a step.
5. Binds to the Workflow from a Worker's fetch handler so that we can create (trigger) instances of our Workflow via a HTTP call.

You can edit this Workflow by adding (or removing) additional step calls, changing the retry configuration, and/or making your own API calls. This Workflow template is designed to illustrate some of Workflows APIs.

2. Deploy a Workflow

Workflows are deployed via wrangler, which is installed when you first ran npm create cloudflare above. Workflows are Worker scripts, and are deployed the same way:

npx wrangler@latest deploy

3. Run a Workflow

You can run a Workflow via the wrangler CLI, via a Worker binding, or via the Workflows REST API.

wrangler CLI

# Trigger a Workflow from the CLI, and pass (optional) parameters as an event to the Workflow.
npx wrangler@latest workflows trigger workflows-tutorial --params={"email": "user@example.com", "metadata": {"id": "1"}}

Refer to the events and parameters documentation to understand how events are passed to Workflows.

Worker binding

You can bind to a Workflow from any handler in a Workers script, allowing you to programatically trigger and pass parameters to a Workflow instance from your own application code.

To bind a Workflow to a Worker, you need to define a [[workflows]] binding in your wrangler.toml configuration:

wrangler.toml

[[workflows]]
# name of your workflow
name = "workflows-starter"
# binding name env.MY_WORKFLOW
binding = "MY_WORKFLOW"
# this is class that extends the Workflow class in src/index.ts
class_name = "MyWorkflow"

You can then invoke the methods on this binding directly from your Worker script's env parameter. The Workflow type has methods for:

• create() - creating (triggering) a new instance of the Workflow, returning the ID.
• get()- retrieve a Workflow instance by its ID.
• status() - get the current status of a unique Workflow instance.

For example, the following Worker will fetch the status of an existing Workflow instance by ID (if supplied), else it will create a new Workflow instance and return its ID:

src/index.ts

// Import the Workflow definition
import { WorkflowEntrypoint, WorkflowStep, WorkflowEvent} from 'cloudflare:workers';

interface Env {
  // Matches the binding definition in your wrangler.toml
  MY_WORKFLOW: Workflow;
}

export default {
  async fetch(req: Request, env: Env): Promise<Response> {
    let id = new URL(req.url).searchParams.get('instanceId');

    // Get the status of an existing instance, if provided
    if (id) {
      let instance = await env.MY_WORKFLOW.get(id);
      return Response.json({
        status: await instance.status(),
      });
    }

    // Spawn a new instance and return the ID and status
    let instance = await env.MY_WORKFLOW.create();
    return Response.json({
      id: instance.id,
      details: await instance.status(),
    });
  },
};

Refer to the triggering Workflows documentation for how to trigger a Workflow from other Workers' handler functions.

4. Manage Workflows

Note

The wrangler workflows command requires Wrangler version 3.83.0 or greater. Use npx wrangler@latest to always use the latest Wrangler version when invoking commands.

The wrangler workflows command group has several sub-commands for managing and inspecting Workflows and their instances:

• List Workflows: wrangler workflows list
• Inspect the instances of a Workflow: wrangler workflows instances list YOUR_WORKFLOW_NAME
• View the state of a running Workflow instance by its ID: wrangler workflows instances describe YOUR_WORKFLOW_NAME WORKFLOW_ID

You can also view the state of the latest instance of a Workflow by using the latest keyword instead of an ID:

npx wrangler@latest workflows instances describe workflows-starter latest
# Or by ID:
# npx wrangler@latest workflows instances describe workflows-starter 12dc179f-9f77-4a37-b973-709dca4189ba

The output of instances describe shows:

• The status (success, failure, running) of each step
• Any state emitted by the step
• Any sleep state, including when the Workflow will wake up
• Retries associated with each step
• Errors, including exception messages

Note

You do not have to wait for a Workflow instance to finish executing to inspect its current status. The wrangler workflows instances describe sub-command will show the status of an in-progress instance, including any persisted state, if it is sleeping, and any errors or retries. This can be especially useful when debugging a Workflow during development.

Next steps

• Learn more about how events are passed to a Workflow.
• Binding to and triggering Workflow instances using the Workers API.
• The Rules of Workflows and best practices for building applications using Workflows.

If you have any feature requests or notice any bugs, share your feedback directly with the Cloudflare team by joining the Cloudflare Developers community on Discord ↗.

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