docker-easy-haproxy/examples/swarm

Docker Swarm Examples

This directory contains Docker Swarm stack examples demonstrating EasyHAProxy in a Swarm cluster environment.

What is Docker Swarm Mode?

Docker Swarm mode enables:

• Service orchestration across multiple nodes
• Service scaling with replicas
• Load balancing across service replicas
• Rolling updates with zero downtime
• Service discovery via overlay networks

EasyHAProxy automatically discovers Swarm services and routes traffic based on service labels.

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Prerequisites

1. Initialize Docker Swarm

# On manager node
docker swarm init

# On worker nodes (use token from swarm init output)
docker swarm join --token <token> <manager-ip>:2377

2. Create Overlay Network

# Create attachable overlay network for EasyHAProxy
docker network create --driver overlay --attachable easyhaproxy

Why attachable? Allows both swarm services and standalone containers to connect.

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Files in This Directory

• easyhaproxy.yml - EasyHAProxy service stack
• services.yml - Example application services
• portainer.yml - Portainer management interface
• certs/ - Directory for SSL certificates

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Quick Start

1. Deploy EasyHAProxy

cd examples/swarm

# Edit easyhaproxy.yml and change:
# EASYHAPROXY_CERTBOT_EMAIL: your-email@example.com

# Deploy stack
docker stack deploy -c easyhaproxy.yml easyhaproxy

What this creates:

• EasyHAProxy service with 1 replica
• Exposed ports: 80, 443, 1936
• Mounts Docker socket for service discovery
• Mounts volume for certbot certificates

2. Deploy Example Services

docker stack deploy -c services.yml myapp

3. (Optional) Deploy Portainer

docker stack deploy -c portainer.yml portainer

---

Example Files Explained

easyhaproxy.yml

version: "3"

services:
  haproxy:
    image: byjg/easy-haproxy:4.6.0
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock  # Service discovery
      - ./certs:/certs/haproxy                     # SSL certificates
      - certs_certbot:/certs/certbot               # Let's Encrypt certs
    deploy:
      replicas: 1                                   # Single instance
    environment:
      EASYHAPROXY_DISCOVER: swarm                  # Swarm mode!
      EASYHAPROXY_SSL_MODE: "loose"
      EASYHAPROXY_CERTBOT_EMAIL: changeme@example.org  # Change this!
      HAPROXY_CUSTOMERRORS: "true"
      HAPROXY_USERNAME: admin
      HAPROXY_PASSWORD: password
      HAPROXY_STATS_PORT: 1936
    ports:
      - "80:80/tcp"
      - "443:443/tcp"
      - "1936:1936/tcp"
    networks:
      - easyhaproxy                                # Overlay network

networks:
  easyhaproxy:
    external: true                                 # Created separately

volumes:
  certs_certbot:                                   # Persistent certbot data

Key differences from Docker Compose mode:

• EASYHAPROXY_DISCOVER: swarm - Discovery mode
• deploy.replicas: 1 - Swarm deployment config
• External overlay network

---

Service Labels in Swarm

Service labels are similar to container labels but applied to services, not containers.

Basic Service Example

version: "3"

services:
  webapp:
    image: nginx:alpine
    deploy:
      replicas: 3           # 3 instances for load balancing
      labels:
        # Service labels (not container labels!)
        easyhaproxy.http.host: "webapp.example.com"
        easyhaproxy.http.port: "80"
        easyhaproxy.http.localport: "80"
    networks:
      - easyhaproxy

Important: Use deploy.labels, NOT top-level labels!

# ✅ CORRECT - Service labels
deploy:
  labels:
    easyhaproxy.http.host: example.com

# ❌ WRONG - Container labels (ignored in Swarm)
labels:
  easyhaproxy.http.host: example.com

---

Common Use Cases

Use Case 1: Simple HTTP Service

version: "3"

services:
  myapp:
    image: my-app:latest
    deploy:
      replicas: 3
      labels:
        easyhaproxy.http.host: "myapp.example.com"
        easyhaproxy.http.port: "80"
        easyhaproxy.http.localport: "3000"
    networks:
      - easyhaproxy

networks:
  easyhaproxy:
    external: true

Deploy:

docker stack deploy -c myapp.yml myapp

Use Case 2: HTTPS with Let's Encrypt

version: "3"

services:
  secure-app:
    image: secure-app:latest
    deploy:
      replicas: 2
      labels:
        easyhaproxy.http.host: "secure.example.com"
        easyhaproxy.http.port: "80"
        easyhaproxy.http.localport: "8080"
        easyhaproxy.http.certbot: "true"
        easyhaproxy.http.redirect_ssl: "true"
    networks:
      - easyhaproxy

networks:
  easyhaproxy:
    external: true

Requirements:

• Public IP with DNS pointing to swarm
• Ports 80/443 open
• Certbot email configured in easyhaproxy.yml

Use Case 3: Multiple Domains, One Service

services:
  webapp:
    image: webapp:latest
    deploy:
      replicas: 4
      labels:
        # Primary domain
        easyhaproxy.http.host: "example.com"
        easyhaproxy.http.port: "80"
        easyhaproxy.http.localport: "8080"

        # Additional domain (www)
        easyhaproxy.http2.host: "www.example.com"
        easyhaproxy.http2.port: "80"
        easyhaproxy.http2.localport: "8080"

        # API subdomain
        easyhaproxy.api.host: "api.example.com"
        easyhaproxy.api.port: "80"
        easyhaproxy.api.localport: "8080"
    networks:
      - easyhaproxy

Use Case 4: Service with Plugins

services:
  api:
    image: api-server:latest
    deploy:
      replicas: 3
      labels:
        easyhaproxy.http.host: "api.example.com"
        easyhaproxy.http.port: "80"
        easyhaproxy.http.localport: "8080"
        # Enable plugins
        easyhaproxy.http.plugins: "jwt_validator,deny_pages"
        # Configure JWT validator
        easyhaproxy.http.plugin.jwt_validator.algorithm: "RS256"
        easyhaproxy.http.plugin.jwt_validator.issuer: "https://auth.example.com/"
        easyhaproxy.http.plugin.jwt_validator.pubkey_path: "/etc/haproxy/jwt_keys/api.pem"
        # Configure deny_pages
        easyhaproxy.http.plugin.deny_pages.paths: "/admin,/private"
        easyhaproxy.http.plugin.deny_pages.status_code: "403"
    networks:
      - easyhaproxy

Use Case 5: Multiple Services with Load Balancing

version: "3"

services:
  frontend:
    image: frontend-app:latest
    deploy:
      replicas: 2
      labels:
        easyhaproxy.http.host: "example.com"
        easyhaproxy.http.port: "80"
        easyhaproxy.http.localport: "3000"
    networks:
      - easyhaproxy

  api:
    image: api-server:latest
    deploy:
      replicas: 5           # More replicas for API
      labels:
        easyhaproxy.http.host: "api.example.com"
        easyhaproxy.http.port: "80"
        easyhaproxy.http.localport: "8080"
    networks:
      - easyhaproxy

  admin:
    image: admin-panel:latest
    deploy:
      replicas: 1
      labels:
        easyhaproxy.http.host: "admin.example.com"
        easyhaproxy.http.port: "80"
        easyhaproxy.http.localport: "4000"
        # Restrict access
        easyhaproxy.http.plugins: "ip_whitelist"
        easyhaproxy.http.plugin.ip_whitelist.allowed_ips: "192.168.1.0/24"
    networks:
      - easyhaproxy

networks:
  easyhaproxy:
    external: true

---

Scaling Services

Scale services dynamically:

# Scale up
docker service scale myapp_webapp=10

# Scale down
docker service scale myapp_webapp=2

# Check replicas
docker service ls

EasyHAProxy automatically detects all replicas and load balances across them.

---

Rolling Updates

Update services with zero downtime:

# Update service image
docker service update --image webapp:v2 myapp_webapp

# Update with custom settings
docker service update \
  --image webapp:v2 \
  --update-parallelism 2 \
  --update-delay 10s \
  myapp_webapp

EasyHAProxy continues routing to healthy containers during rollout.

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Management Commands

View Stacks

docker stack ls

View Services in Stack

docker stack services myapp

View Service Details

docker service inspect myapp_webapp

View Service Logs

docker service logs -f myapp_webapp

Update Service Labels

docker service update \
  --label-add easyhaproxy.http.certbot=true \
  myapp_webapp

Remove Stack

docker stack rm myapp

---

SSL Certificates in Swarm

Option 1: Let's Encrypt (Recommended)

Configure in easyhaproxy.yml:

environment:
  EASYHAPROXY_CERTBOT_EMAIL: your-email@example.com

Enable per-service:

deploy:
  labels:
    easyhaproxy.http.certbot: "true"

Option 2: Custom Certificates

Mount certificates directory:

# easyhaproxy.yml
volumes:
  - ./certs:/certs/haproxy

Place certificate files:

./certs/
  ├── example.com.pem
  ├── api.example.com.pem
  └── secure.example.com.pem

Option 3: Docker Secrets (Production)

# Create secret
docker secret create example_com_cert ./example.com.pem

# Use in stack
version: "3"
services:
  haproxy:
    secrets:
      - example_com_cert
    environment:
      EASYHAPROXY_SSL_CERT_example_com: /run/secrets/example_com_cert

secrets:
  example_com_cert:
    external: true

---

Monitoring and Stats

HAProxy Stats Interface

Access at: http://<swarm-ip>:1936

• Username: admin (configured in easyhaproxy.yml)
• Password: password (configured in easyhaproxy.yml)

Service Health

# Check service health
docker service ps myapp_webapp

# View detailed service info
docker service inspect --pretty myapp_webapp

---

Troubleshooting

Service Not Detected

Check service labels:

docker service inspect myapp_webapp | grep -A 20 Labels

Ensure labels are under deploy.labels, not top-level labels.

Check EasyHAProxy logs:

docker service logs -f easyhaproxy_haproxy

Service Unreachable (503)

Causes:

• Service containers not ready yet
• Wrong network configuration
• Service crashed

Debug:

# Check service is running
docker service ps myapp_webapp

# Check network
docker network inspect easyhaproxy

# Test service directly
docker run --rm --network easyhaproxy alpine \
  wget -O- http://myapp_webapp:8080

Overlay Network Issues

Create network if missing:

docker network create --driver overlay --attachable easyhaproxy

Verify service is on network:

docker service inspect myapp_webapp | grep -A 5 Networks

EasyHAProxy Not Starting

Check Docker socket permissions:

docker service logs easyhaproxy_haproxy

Verify socket is mounted:

docker service inspect easyhaproxy_haproxy | grep -A 5 Mounts

Certificate Issues

Certbot fails:

• Ensure swarm is publicly accessible
• Check DNS points to swarm IP
• Verify ports 80/443 are open
• Check certbot logs: docker service logs easyhaproxy_haproxy | grep certbot

Custom cert not found:

# Exec into service container
docker exec -it $(docker ps -q -f name=easyhaproxy) sh
ls -la /certs/haproxy/

---

High Availability Setup

Multiple Manager Nodes

# On additional manager nodes
docker swarm join-token manager
# Use token on new nodes

EasyHAProxy Constraints

Run EasyHAProxy on specific node:

services:
  haproxy:
    deploy:
      placement:
        constraints:
          - node.role == manager
          - node.labels.haproxy == true

Label node:

docker node update --label-add haproxy=true <node-name>

Multiple EasyHAProxy Replicas

Not recommended - EasyHAProxy should run as single instance because:

• Multiple instances would compete for port binding
• Use external load balancer (cloud LB, keepalived, etc.) for HA

Alternative HA pattern:

Internet → Cloud Load Balancer → Multiple Swarm Nodes
                                  └→ EasyHAProxy (runs on 1 node)
                                     └→ Services (distributed across nodes)

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Best Practices

1. Use Overlay Networks:

   • Create dedicated network for EasyHAProxy
   • Use --attachable for flexibility

2. Service Labels:

   • Always use deploy.labels, never top-level labels
   • Use clear, descriptive domain names

3. Replicas:

   • Start with 2-3 replicas per service
   • Scale based on load monitoring
   • Use odd number for consensus (3, 5, 7)

4. Updates:

   • Use rolling updates for zero downtime
   • Set appropriate update-delay
   • Test in staging first

5. Monitoring:

   • Enable HAProxy stats
   • Use Portainer for visual management
   • Monitor service health regularly

6. Security:

   • Use Docker secrets for sensitive data
   • Restrict admin panel access
   • Use SSL/TLS for production
   • Apply IP whitelisting for admin interfaces

7. Persistence:

   • Use volumes for certbot certificates
   • Backup certificate volumes
   • Store custom certs in version control (encrypted)

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Further Reading

• Docker Swarm Documentation
• Container Labels Reference
• Using Plugins
• ACME/Let's Encrypt
• Environment Variables
• Official Docker Swarm Docs