hello-world

Hello World - Render Workflows (TypeScript)

This hello-world example demonstrates three foundational workflow patterns:

• A minimal task definition (calculateSquare)
• A task that chains runs of another task (sumSquares)
• A task with custom retry behavior (flipCoin)

What You'll Learn

• How to define tasks with task(...)
• How to chain task runs using await and Promise.all
• How to customize retry behavior with retry

Example Tasks

calculateSquare(a: number): number

The smallest possible task: takes one number and returns its square.

sumSquares(a: number, b: number): Promise<number>

Chains two runs of calculateSquare and sums the results.

It uses Promise.all(...) to chain the two runs in parallel:

const [result1, result2] = await Promise.all([
  calculateSquare(a),
  calculateSquare(b),
]);

flipCoin(): string

Simulates a coin flip:

• Heads: Returns success
• Tails: Raises an error to trigger retry

Retry policy in this example:

• max retries: 3
• wait duration: 1000ms
• backoff scaling: 1.5

Local Development

Prerequisites

• Node.js 18+

Run locally

Make sure you've installed the latest version of the Render CLI.

1. From this template's root, start the local task server:

   npm install
   render workflows dev -- npm start

2. In a separate terminal, trigger task runs:

   render workflows tasks start calculateSquare --local --input='[5]'
   render workflows tasks start sumSquares --local --input='[3,4]'
   render workflows tasks start flipCoin --local --input='[]'

Expected behavior:

• calculateSquare with 5 returns 25
• sumSquares with 3,4 returns 25
• flipCoin may fail and retry before succeeding

Deploying to Render

Configure your Workflow service with:

Option	Value
Build command	npm install
Start command	npm start

Key Concepts

Task registration

Any call to task({ name: ... }, handler) registers a runnable workflow task.

Chaining runs

Inside an async task, calling await anotherTask(...) chains a run of that task.

Retries

Use the retry option in task config when transient failures should be retried automatically.

Troubleshooting

"Task not found"

• Confirm the service is running
• Verify task names exactly match: calculateSquare, sumSquares, flipCoin

Import or dependency issues

• Confirm dependency install completed from package.json
• Confirm Node.js version is 18+

Resources

• Render Workflows documentation
• Workflows tutorial
• Local development guide