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Can --link be made more robust for ip/port mappings


(Sam Saffron) #1

I was considering using --link to link up default Discourse data and web containers.

Trivially the trick you would follow is:

docker run -d -p 80 --name data ubuntu /bin/sleep 999999
docker run -it --rm  --name web --link data ubuntu /bin/bash

All is good in the web container, if I run:

# env
...
DATA_PORT_80_TCP=tcp://172.17.0.79:80

Which is fantastic

BUT… if I restart my data container it gets a new IP.

Now DATA_PORT_80_TCP does not point at the correct IP address so effectively my environment is in a broken state.

My suggestions / feature request

  • Can an extra var be added that forces all depending containers to restart if a parent linked container restarts (which would force the env refresh)

  • Can/will docker act as a DNS server to provide a proper lookup for the IP for depending containers?

As it is … this link by ip/port feature is mostly useless to us as it is not resilient or restarts and can lead to very bad and hard to troubleshoot environments.


(Sven Dowideit) #2

have you played with the experimental networking code?


(Sam Saffron) #3

Not yet, I may have a go playing with libnetwork