docker-ambassador

A maintained version of the ambassador linking pattern.

This ambassador image can be used to automatically proxy all exposed ports from the linked container, or to proxy a specified port at a specific IP address or hostname.

Use Docker linking to autoattach to all exposed ports

# start a container that exposes a port
docker run --rm --name nginx.1 nginx

# run the ambassador 
docker run --rm -ti --link nginx.1 -p 9999:80 -p 8888:443 dokku/ambassador

Running the ambassador container will result in output lke the following.

Connecting to 172.17.0.4:80 172.17.0.4:443...
2016/01/12 13:03:14 socat[19] E connect(5, AF=2 172.17.0.4:443, 16): Connection refused

You can also proxy exposed ports from more than one container by using more than one –link, but only if there is no duplication of exposed container ports.

Specify host and port

This will allow you Dynamically map a container port after its been created.

For example:

# start a container that exposes a port
docker run --rm --name nginx.1 nginx

In the above example, nginx is running, but no-one can make requests to it. By running:

# Assuming the nginx.1 container is on IP `172.17.0.4`
docker run --rm -p 9999:80 dokku/ambassador 172.17.0.4 80

You will now be able to make requests to the web server on http://localhost:9999

Credit

Thanks to Sven Dowideit for providing the initial implementation.