Redundancy Failover with Traefik

What is Traefik?

Traefik is a modern, open-source reverse proxy and load balancer for microservice-oriented architectures. It supports multiple backends such as Docker and Kubernetes, offers automatic service discovery, SSL/TLS encryption, and easy management via a dashboard or API.

There are several ways to configure Traefik, as different "providers" can be used for configuration, e.g., files and Docker.

The following section first discusses the configuration of Traefik with files, as this type of configuration is universally applicable. Later, an example will be used to show how Traefik can be configured in Docker Compose.

Configuring failover with files

The general configuration of Traefik for using configuration files could look like this. In this example, all configuration files in the /etc/traefik/traefik_configs folder are used to configure Traefik.

traefik.yaml

api:
  dashboard: true
  insecure: true

ping: {}

providers:
  file:
    # Specifies the directory where the configuration files are located.
    directory: /etc/traefik/traefik_configs

entryPoints:
  web:
    address: ":80"

A configuration file for failover for an OPC Router redundancy pair could look like this. This file must be located in the configured directory for configuration files.

redundancy_failover.yaml

http:
  routers:
    api-router:
      # Responds to the prefix /api
      rule: "PathPrefix(`/api`)"
      # Sends requests to opcrouter-service
      service: opcrouter-service
      entryPoints:
        - web
      middlewares:
        - api-rewrite

  middlewares:
    api-rewrite:
      # Replaces /api/ with /services/MyRestServer/api/
      replacePathRegex:
        regex: "^/api/(.*)"
        replacement: "/services/MyRestServer/api/$1"

  services:
    opcrouter-service:
      loadBalancer:
        # Servers in the redundancy pair
        servers:
          - url: "http://opcrouter-primary:8080"
          - url: "http://opcrouter-secondary:8080"
        # Sends requests to the specified path to test availability
        healthCheck:
          path: "/health/runtime/ready"
          interval: "5s"
          timeout: "2s"