Backend.AI App Proxy Coordinator

Purpose

The App Proxy Coordinator manages routing information for App Proxy Workers, coordinates worker instances, and handles service port mappings for compute session services (Jupyter, SSH, TensorBoard, etc.).

Key Responsibilities

1. Worker Management

• Register and track App Proxy Worker instances
• Monitor worker health and availability
• Distribute routing information to workers
• Handle worker failover

2. Route Management

• Manage service port mappings (session → service → port)
• Update routing tables dynamically
• Propagate route changes to workers
• Handle route conflicts and resolution

3. Service Discovery

• Maintain service registry
• Provide route lookup for workers
• Update routes when sessions change
• Clean up routes for terminated sessions

Entry Points

App Proxy Coordinator has 1 entry point to receive and process requests.

1. REST API

Framework: aiohttp (async HTTP server)

Port: 6030 (default)

Primary Purpose:

• Worker management (registration, monitoring)
• Routing information management (session-to-service port mapping)

Key Features:

• HTTP/HTTPS-based communication
• Centralized service routing information management
• Real-time route updates
• Persistent routing information storage in PostgreSQL

Processing Flow:

Worker Registration Flow

Worker → POST /workers/register → Coordinator
                                      ↓
                                  Register worker in DB
                                      ↓
                                  Return worker ID and routes

Route Creation Flow

Manager → POST /routes → Coordinator
                             ↓
                         Store route in DB
                             ↓
                         Notify all workers
                             ↓
                         Workers update local routing table

Integrated Architecture:

┌──────────────┐
│   Manager    │
│              │
└──────┬───────┘
       │ Route Management (REST)
       ▼
┌─────────────────────────────────────┐
│  App Proxy Coordinator (Port 6030)  │
│  - Worker registration              │
│  - Route management                 │
│  - Service port mapping             │
│  - Route propagation                │
└─────────┬───────────────────────────┘
          │
          ▼ Worker Registration & Route Updates
    ┌─────┴─────┬─────────┬─────────┐
    ▼           ▼         ▼         ▼
┌────────┐ ┌────────┐ ┌────────┐ ┌────────┐
│Worker 1│ │Worker 2│ │Worker 3│ │Worker N│
└────────┘ └────────┘ └────────┘ └────────┘