This Docker image helps you start your own apex/root to www redirecting HTTP server.

When Docker is installed, run this:

$ docker run --name apex2www --detach \
  --restart=always --publish 80:80 \
  yegor256/apex2www

Now you can point A DNS record of your domain to the IP address of the server where the Docker container is running. Once an HTTP request arrives, it will automatically be redirected to the www. hostname.