I have a lot of docker containers that I need addressable on the the same LAN as their hosts. Up until now, I have been achieving this by using setting up a bridge and manually assigning them IPs, and managing the IPs myself. An example startup would be like so:
docker run \ --net="none" \ \ --lxc-conf="lxc.network.type = veth" \ --lxc-conf="lxc.network.ipv4 = 192.168.1.3/24" \ --lxc-conf="lxc.network.ipv4.gateway = 192.168.1.254" \ --lxc-conf="lxc.network.link = br0" \ --lxc-conf="lxc.network.name = eth0" \ --lxc-conf="lxc.network.flags = up" \ -d [Docker Image ID]
With the host having the bridge defined in
/etc/network/interfaces (ubuntu) like so:
auto eth0 iface eth0 inet manual auto br0 iface br0 inet static address 192.168.1.2 netmask 255.255.255.0 gateway 192.168.1.254 bridge_ports eth0 bridge_stp off bridge_fd 0 bridge_maxwait 0
Since I discovered serf, I have been trying to move over to using automatic discovery within the containers, so that DHCP can keep track of IPs and hand them out to containers. I since changed the startup command to:
docker run \ --net="none" \ --lxc-conf="lxc.network.type = veth" \ --lxc-conf="lxc.network.link = br0" \ --lxc-conf="lxc.network.flags = up" \ -d [Docker Image ID] /bin/bash
and the bridge to:
auto br0 iface br0 inet dhcp bridge_ports eth0 bridge_stp off bridge_fd 0 bridge_maxwait 0
This resulted in the container starting up, but not having an IP. I then took advice from an online post who managed to get it done with Fedora, by calling
dhclient. Unfortunately this is not working for me within ubuntu based containers.
Below are the following error messages I get under different conditions:
dhclientwhen I have enabled
--privilegedin starting the container:
dhclient: error while loading shared libraries: libc.so.6: cannot open shared object file: Permission denied
sudo dhclient eth0when not in
RTNETLINK answers: Operation not permitted mv: cannot move '/etc/resolv.conf.dhclient-new.31' to '/etc/resolv.conf': Device or resource busy
dhclient(no interface specified).
Returns immediately and there is still no IP or network connectivity.
How can I get docker containers to grab dynamic IPs from the same subnet as their hosts, such that I can deploy containers across multiple hosts without tracking IPs?
- Host is Ubuntu 14.04
- Docker containers are built using
from ubuntu:14.04in the Dockerfile.