Network Groups

Group multiple applications into shared networks for inter-service communication.

Configuration

[network_groups]
"backend" = ["app.mydomain.com", "api.mydomain.com"]
"monitoring" = ["grafana.mydomain.com", "prometheus.mydomain.com"]

Syntax

[network_groups]
"<group-name>" = ["<domain>", "<domain>", ...]

How It Works

Network groups create shared Docker networks for multiple applications:

[network_groups]
"backend" = ["app.mydomain.com", "api.mydomain.com"]

Creates a shared network: gordon-backend

┌────────────────────────────────────────────────┐
│ gordon-backend                                 │
│                                                │
│  ┌──────────┐    ┌──────────┐    ┌──────────┐  │
│  │   App    │←──→│   API    │←──→│ Postgres │  │
│  │  :3000   │    │  :8080   │    │  :5432   │  │
│  └──────────┘    └──────────┘    └──────────┘  │
│                                                │
└────────────────────────────────────────────────┘

Service Discovery

Applications in the same group can communicate using container names:

[routes]
"app.mydomain.com" = "frontend:latest"
"api.mydomain.com" = "backend:latest"

[network_groups]
"services" = ["app.mydomain.com", "api.mydomain.com"]

Server-side code (SSR, API routes) can reach other containers by name:

// In server-side code (SSR / API route) - NOT browser JavaScript
const response = await fetch("http://backend:8080/api/data");

Browser clients should use the public route instead:

// In browser JavaScript
const response = await fetch("https://api.mydomain.com/api/data");

Shared Attachments

Combine network groups with attachments for shared services:

[network_groups]
"backend" = ["app.mydomain.com", "api.mydomain.com"]

[attachments]
"backend" = ["postgres:latest", "redis:latest"]

Both app.mydomain.com and api.mydomain.com can access:

• postgres:5432
• redis:6379

Multiple Groups

An application can only be in one network group:

# Each app belongs to one group
[network_groups]
"customer-facing" = ["app.mydomain.com", "api.mydomain.com"]
"internal" = ["admin.mydomain.com", "metrics.mydomain.com"]

Mixed Isolation

Combine network groups with per-app attachments:

[network_groups]
"backend" = ["app.mydomain.com", "api.mydomain.com"]

[attachments]
# Shared by both apps
"backend" = ["redis:latest", "rabbitmq:latest"]

# App-specific databases
"app.mydomain.com" = ["app-postgres:latest"]
"api.mydomain.com" = ["api-postgres:latest"]

Result:

• Shared: Redis and RabbitMQ
• Isolated: Each app has its own Postgres

Examples

Microservices Architecture

[routes]
"orders.mydomain.com" = "orders-service:latest"
"inventory.mydomain.com" = "inventory-service:latest"
"shipping.mydomain.com" = "shipping-service:latest"
"payments.mydomain.com" = "payments-service:latest"

[network_groups]
"order-processing" = ["orders.mydomain.com", "inventory.mydomain.com", "shipping.mydomain.com"]
"payment-processing" = ["payments.mydomain.com"]

[attachments]
"order-processing" = ["rabbitmq:latest"]
"payments.mydomain.com" = ["payments-db:latest"]

Monitoring Stack

[routes]
"grafana.mydomain.com" = "grafana/grafana:latest"
"prometheus.mydomain.com" = "prom/prometheus:latest"
"alertmanager.mydomain.com" = "prom/alertmanager:latest"

[network_groups]
"monitoring" = ["grafana.mydomain.com", "prometheus.mydomain.com", "alertmanager.mydomain.com"]

[attachments]
"monitoring" = ["prometheus-data:latest"]

Multi-Tenant SaaS

[routes]
"app.saas.com" = "saas-app:latest"
"api.saas.com" = "saas-api:latest"
"admin.saas.com" = "saas-admin:latest"

# API and App share backend services
[network_groups]
"platform" = ["app.saas.com", "api.saas.com"]

# Admin is isolated
[attachments]
"platform" = ["postgres:latest", "redis:latest", "elasticsearch:latest"]
"admin.saas.com" = ["admin-db:latest"]

Network Naming

Group networks are named: {network_prefix}-{group-name}

Related

• Network Isolation
• Attachments
• Routes