Docker containers serving different subdomains on port 80

Question

Is it possible to have a 2 docker containers serve on port 80 but different subdomains or hostnames?

Something like:

api.example.com goes to a node application

app.example.com goes to a Java application

Answer 1

Yes you can. using a proxy.

There is a project by jwilder/nginx-proxy which allows you to give your hostname via an enviroment variable which will than route your request to the appropriate container.

A good example of this implemented is given here: https://blog.florianlopes.io/host-multiple-websites-on-single-host-docker/

Answer 2

No. The first container you start will have exclusive access to the port, and if you try and start a second container on the same port it will fail.

Instead, use a load balancer such as Nginx or Traefik to handle the incoming traffic to port 80 and proxy it on to your two app containers based on host headers.