Node-RED Flow Development

This skill provides comprehensive support for Node-RED development, including flow creation, modification, validation, and deployment through the Admin API.

When to Use This Skill

Use this skill when:

• Creating or modifying Node-RED flows (flows.json files)
• Building MQTT, HTTP API, or data pipeline integrations
• Debugging or validating flow configurations
• Working with function nodes and context storage
• Deploying flows via the Node-RED Admin API
• Converting requirements into Node-RED flow implementations

Available Resources

Scripts (scripts/)

Execute these Python scripts for common Node-RED operations:

• generate_uuid.py - Generate valid Node-RED node IDs

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  python scripts/generate_uuid.py [count]
  

• validate_flow.py - Validate flow JSON structure and wire connections

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  python scripts/validate_flow.py <flow.json>
  

• wire_nodes.py - Connect nodes programmatically

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  python scripts/wire_nodes.py <flow.json> <source_id> <target_id> [output_port]
  

• create_flow_template.py - Generate boilerplate flows

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  python scripts/create_flow_template.py <mqtt|http-api|data-pipeline|error-handler> [output.json]
  

References (references/)

Consult these detailed references as needed:

• node_schemas.md - Complete schemas for all Node-RED node types
• api_reference.md - Node-RED Admin API documentation with examples
• function_snippets.md - Reusable function node code patterns

Assets (assets/)

Use these templates and boilerplate files:

• templates/mqtt_flow.json - Complete MQTT pub/sub flow with error handling
• templates/http_api_flow.json - REST API with CRUD operations and authentication
• boilerplate/function_async.js - Async function node patterns
• boilerplate/function_context.js - Context storage examples

Core Workflow

Creating a New Flow

1. Determine the flow type needed (MQTT, HTTP API, data processing, etc.)
2. Generate a template using scripts/create_flow_template.py
3. Modify the template to match requirements
4. Validate the flow using scripts/validate_flow.py
5. Deploy via Admin API or save as flows.json

Modifying Existing Flows

1. Read and parse the flows.json file
2. Identify nodes by type and ID
3. Make modifications while preserving:
   • Wire connections (arrays of node IDs)
   • Tab references (z property)
   • Node coordinates (x, y)
4. Validate changes before saving
5. Use scripts/wire_nodes.py to connect nodes if needed

Working with Function Nodes

For function nodes, reference:

• assets/boilerplate/function_async.js for async operations
• assets/boilerplate/function_context.js for context storage
• references/function_snippets.md for specific patterns

Available objects in function nodes:

• msg - Message object
• node - Node API (send, done, error, warn, log, status)
• context - Node-scoped storage
• flow - Flow-scoped storage
• global - Global storage
• RED - Runtime API
• env - Environment variables

Deploying Flows

To deploy flows via the Admin API:

1. Retrieve current configuration:

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   GET /flows
   

2. Modify the configuration as needed

3. Deploy with appropriate deployment type:

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   POST /flows
   Headers: Node-RED-Deployment-Type: full|nodes|flows|reload
   

4. Verify deployment success

Common Patterns

Message Flow Structure

Every Node-RED message follows this pattern:

• Primary data in msg.payload
• Topic/category in msg.topic
• Unique ID in msg._msgid
• Additional properties as needed

Error Handling

Implement error handling using:

1. Try-catch blocks in function nodes
2. Catch nodes to intercept errors
3. Status nodes to monitor node states
4. Dedicated error output wires

Environment Variables

Use environment variables for configuration:

• In node properties: $(ENV_VAR_NAME)
• In function nodes: env.get("ENV_VAR_NAME")
• Via Docker: -e KEY=value

Context Storage Levels

Choose appropriate context level:

• Node context: Local to single node
• Flow context: Shared within flow/tab
• Global context: System-wide sharing
• Persistent: Survives restarts (configure in settings.js)

Validation Checklist

Before deploying flows, verify:

• JSON syntax is valid
• All wire connections reference existing node IDs
• Tab references (z property) are correct
• Function node JavaScript is syntactically valid
• Required configuration nodes exist (MQTT brokers, etc.)
• Environment variables are properly referenced
• Error handling is implemented

Quick Commands

Generate five Node-RED UUIDs:

python scripts/generate_uuid.py 5

Create an MQTT flow template:

python scripts/create_flow_template.py mqtt my-mqtt-flow.json

Validate a flow file:

python scripts/validate_flow.py flows.json

Wire two nodes together:

python scripts/wire_nodes.py flows.json inject-node-id debug-node-id

Node-RED Configuration

Default File Locations

• Flows: ~/.node-red/flows_<hostname>.json
• Settings: ~/.node-red/settings.js
• Custom nodes: ~/.node-red/node_modules/

Running Node-RED

• Normal mode: node-red
• Safe mode (no flow execution): node-red --safe
• Custom flow file: node-red myflows.json

Best Practices

1. Use appropriate node types: Prefer change nodes over function nodes for simple transformations
2. Implement error handling: Always include catch nodes for critical paths
3. Document flows: Use comment nodes and node descriptions
4. Organize with tabs: Separate flows by logical function or system
5. Version control: Store flows.json in git with meaningful commit messages
6. Test incrementally: Deploy and test small changes frequently
7. Monitor performance: Use status nodes and debug output wisely

Troubleshooting

For common issues:

• Invalid JSON: Use scripts/validate_flow.py to find syntax errors
• Broken wires: Check that all wired node IDs exist
• Missing configurations: Ensure broker/server configs are included
• Function errors: Test JavaScript in isolation first
• API deployment fails: Verify authentication and check revision conflicts

Additional Resources

For detailed specifications and examples:

• Consult references/node_schemas.md for node property details
• Review references/api_reference.md for API operations
• Use references/function_snippets.md for tested code patterns
• Copy templates from assets/templates/ as starting points