scps/skills/render-workflows/references/local-development.md

Local Development

Run workflow tasks locally for faster development and testing.

Contents

• Prerequisites
• Starting the local task server
• Triggering task runs (CLI and application code)
• Viewing results
• Limitations

Prerequisites

• Render CLI 2.11.0+: render --version
  • macOS: brew install render
  • Linux/macOS: curl -fsSL https://raw.githubusercontent.com/render-oss/cli/main/bin/install.sh | sh
  • Windows: download the executable from the CLI releases page
• A workflow project with registered tasks

Starting the Local Task Server

From your project directory:

# Python
render workflows dev -- python workflows/main.py

# TypeScript
render workflows dev -- npx tsx workflows/main.ts

The local server starts on port 8120. Customize with --port:

render workflows dev --port 8121 -- python workflows/main.py

The server picks up code changes automatically as you iterate.

Triggering Task Runs

From the CLI

List and run tasks interactively:

render workflows tasks list --local

The --local flag is required. Without it, the CLI lists deployed (remote) tasks.

The interactive menu lets you:

1. Select a task
2. Choose run
3. Provide input as a JSON array (e.g., [5] or [])
4. View live logs

From Application Code

Configure your app to target the local task server.

Python:

Set environment variables:

RENDER_USE_LOCAL_DEV=true

Or for a custom port:

RENDER_USE_LOCAL_DEV=true
RENDER_LOCAL_DEV_URL=http://localhost:8121

The SDK clients (Render() and RenderAsync()) automatically detect these and route requests to the local server.

TypeScript:

Same environment variables:

RENDER_USE_LOCAL_DEV=true

Or pass configuration directly:

import { Render } from "@renderinc/sdk";

const render = new Render({
  useLocalDev: true,
  localDevUrl: "http://localhost:8120",
});

Render API (any language):

Swap the base URL for task endpoints:

http://localhost:8120

The local task server only simulates task-related endpoints. Other Render API endpoints are not supported locally.

Viewing Results

After running a task via the CLI:

1. Press Esc to go back to the command menu
2. Select runs to see task runs
3. Select a run and choose results to see output

Limitations

• Logs and results are stored in memory and lost on server shutdown
• High volume of runs can increase memory usage; restart the server periodically
• Task and run IDs are random UUIDs, not matching deployed identifiers
• Subtasks run locally in the same server process