Docker Mapping

Ports

How can someone access your application?

docker run webapp
>> * Running on http://0.0.0.0:5000/

You can access it through port 5000 (the docker container is listening/exposed from this port), but what IP do we use?

1. The IP of the docker container (every docker container gets a default IP address)

   • IMPORTANT NOTE: This is internal and is only accessible within the docker host. So opening a browser within the docker browser would yield the application.

   • e.g. http://172.17.0.2:5000/

2. The IP of the docker host

   • You must map port inside docker container to free port on docker host (e.g. map port 80 from localhost to port 5000)

   • e.g. http://192.168.1.5:80/

   • Command to map the port: docker run -p 80:5000 <name>

     • All traffic to port 80 gets routed to port 5000 inside the docker container

     • This way, we can run multiple instances of the application and map the instances to different ports at the same time

Volumes

When you remove a container, all the data goes with it. How do we persist the data? We have to map the data stored in the container to a local location:

docker run -v <local/file/path>:/var/lib/mysql mysql