Imagine that you have deployed a bunch of microservices on your infrastructure. You probably used a service registry (like etcd or consul) and/or an orchestrator (swarm, Mesos/Marathon) to manage all these services. If you want your users to access some of your microservices from the Internet, you will have to use a reverse proxy and configure it using virtual hosts or prefix paths:

• domain api.domain.com will point the microservice api in your private network
• path domain.com/web will point the microservice web in your private network
• domain backoffice.domain.com will point the microservices backoffice in your private network, load-balancing between your multiple instances But a microservices architecture is dynamic... Services are added, removed, killed or upgraded often, eventually several times a day. Traditional reverse-proxies are not natively dynamic. You can't change their configuration and hot-reload easily. Here enters Træfik.