I came here because I was trying to use ifconfig on the container to find its IPAaddress and there was no ifconfig. If you really need ifconfig on the container go with @vishnu-narayanan answer above, however you may be able to get the information you need by using docker inspect on the host:
docker inspect <containerid>
There is lots of good stuff in the output including IPAddress of container:
"Networks": {
"bridge": {
"IPAMConfig": null,
"Links": null,
"Aliases": null,
"NetworkID": "12345FAKEID",
"EndpointID": "12345FAKEENDPOINTID",
"Gateway": "172.17.0.1",
"IPAddress": "172.17.0.3",
"IPPrefixLen": 16,
"IPv6Gateway": "",
"GlobalIPv6Address": "",
"GlobalIPv6PrefixLen": 0,
"MacAddress": "01:02:03:04:05:06",
"DriverOpts": null
}
}