docker-route-mac-to-containers.md

This is a demo of how to talk between programs running on a Mac, and programs running under Docker on a VM on the same Mac as installed by Docker Toolbox.

Just add a route to your containers using the VM as the gateway. Demo:

• on the mac, run Docker Quickstart Terminal from the latest Docker Toolbox. This launches the virtualbox VM, and configures your shell
• in that shell, figure out the IP address of the VM:

mak@crab 493 ~ $ docker-machine inspect default -f '{{ .Driver.IPAddress }} '
192.168.99.100 

• figure out the addresses used by the docker0 bridge in the VM:

mak@crab 495 ~ $ docker-machine ssh default ip -4 addr list docker0
5: docker0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default 
    inet 172.17.0.1/16 scope global docker0
       valid_lft forever preferred_lft forever

• now add a route for that subnet on your mac:

mak@crab 496 ~ $ sudo route add 172.17.0.0/16  192.168.99.100
Password:
add net 172.17.0.0: gateway 192.168.99.100

• run up a container, print its IP address, and run a server listening on port 6655:

root@56432ab778ae:/# ip -4 addr list eth0
10: eth0@if11: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default 
    inet 172.17.0.2/16 scope global eth0
       valid_lft forever preferred_lft forever
root@56432ab778ae:/# nc.openbsd -l -p 7768

• from the mac whisper sweet nothings into its ear:

mak@crab 548 ~ $ echo "shi" | nc 172.17.0.2 7768
mak@crab 549 ~ $ 

and watch it come out the other end:

root@56432ab778ae:/# nc.openbsd -l -p 7768
shi

And it works the other direction too:

mak@crab 488 ~ $ ifconfig 
...
en0: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500
...
mak@crab 491 ~ $ nc -l 0.0.0.0 7766

 root@56432ab778ae:/# nc 192.168.88.9 7766
jo

mak@crab 491 ~ $ nc -l 0.0.0.0 7766
jo

In my condition，after 'route add' operation，vm's iptables must by be set by:
sudo iptables -I DOCKER-USER -j ACCEPT