Assemblies Overview

Assemblies are visual workflow builders that let you design complex API orchestration without writing code. Chain authentication, rate limiting, transformations, caching, and more in a drag-and-drop interface.

What are Assemblies?

An Assembly is a directed graph of policy nodes that execute on API requests. Think of it as a visual programming language for API traffic control.

┌─────────┐    ┌─────────────┐    ┌───────────┐    ┌─────────┐
│  Auth   │───▶│ Rate Limit  │───▶│ Transform │───▶│ Invoke  │
└─────────┘    └─────────────┘    └───────────┘    └─────────┘

Key Features

• Visual Editor - Drag-and-drop workflow builder
• 21+ Policy Types - Auth, rate limit, transform, cache, validate, and more
• Real-time Testing - Test workflows instantly with built-in API tester
• Execution Logs - Track every node execution with detailed traces
• YAML Import/Export - Git-friendly workflow definitions
• Hot Reload - Changes apply instantly without restarts

Assembly Types

Type	Description	Use Case
Preflow	Executes before backend call	Authentication, validation, rate limiting
Postflow	Executes after backend response	Response transformation, caching, logging
Error	Executes on errors	Error handling, fallbacks, notifications
Standalone	Independent workflow	Scheduled tasks, webhooks

Assembly Scopes

Scope	Description
Global	Organization-level (enforced on all requests)
Project	Project-level policies
Gateway	Gateway-level policies
Route	Route-specific policies

Quick Example

Here's a simple preflow assembly that authenticates requests and applies rate limiting:

apiVersion: tunnelapi.in/v1
kind: Assembly
metadata:
  name: API Security Flow
spec:
  type: preflow
  entryNodeId: auth-node
  nodes:
    - id: auth-node
      type: auth
      name: JWT Authentication
      config:
        type: jwt
        jwt:
          secret: ${env.JWT_SECRET}
    - id: rate-limit-node
      type: rate-limit
      name: Rate Limiter
      config:
        windowMs: 60000
        maxRequests: 100
  edges:
    - source: auth-node
      target: rate-limit-node

Next Steps

• Policy Types - Learn about all 21+ policy types
• Creating Assemblies - Step-by-step guide
• Visual Editor - Using the drag-and-drop builder
• Examples - Real-world workflow examples