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node-red

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Edit, analyze, and create Node-RED flows by working with flows.json files, understanding node types, and applying Node-RED best practices. Use when the user mentions Node-RED, flows.json, flow development, or needs to modify Node-RED configurations.

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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

    python scripts/generate_uuid.py [count]

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

    python scripts/validate_flow.py <flow.json>

  • wire_nodes.py - Connect nodes programmatically

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

  • create_flow_template.py - Generate boilerplate flows

    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:

    GET /flows

  2. Modify the configuration as needed

  3. Deploy with appropriate deployment type:

    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