Docker containers in real life

Question

I have been following the tutorials and been experimenting with Docker for a couple of days but I can't find any "real-world" usage example..

How can I communicate with my container from the outside?

All examples I can find ends up with 1 or more containers, they can share ports with their-others, but no-one outside the host gets access to their exposed ports.

Isn't the whole point of having containers like this, that at least 1 of them needs to be accessible from the outside?

I have found a tool called pipework (https://github.com/jpetazzo/pipework) which probably will help me with this. But is this the tool everyone testing out Docker for production what they are using?

Is a "hack" necessary to get the outside to talk to my container?

Answer 1

You can use the argument -p to expose a port of your container to the host machine.

For example:

  sudo docker run -p80:8080 ubuntu bash

Will bind the port 8080 of your container to the port 80 of the host machine.

Therefore, you can then access to your container from the outside using the URL of the host:

  http://you.domain -> losthost:80 -> container:8080

Is that what you wanted to do? Or maybe I missed something

(The parameter -expose only expose port to other containers (not the host))

Answer 2

This (https://blog.codecentric.de/en/2014/01/docker-networking-made-simple-3-ways-connect-lxc-containers/) blog post explains the problem and the solution.

Basicly, it looks like pipeworks (https://github.com/jpetazzo/pipework) is the way to expose container ports to the outside as of now... Hope this gets integrated soon..

Update: In this case, iptables was to blame, and there was a rule that blocked forwarded traffic. Adding -A FORWARD -i em1 -o docker0 -j ACCEPT solved it..