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Version: 5.4

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 a configuration, e.g. files and Docker.

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

Configuration of failover with files​

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

api:
  dashboard: true
  insecure: true

ping: {}

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

entryPoints:
  web:
    address: ":80"

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

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:
        # Server of 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"