[MESOS-6269] CNI isolator doesn't activate loopback interface

• Type: Bug
• Status: Resolved
• Priority: Blocker
• Resolution: Fixed
• Affects Version/s: 1.0.1
• Fix Version/s: 1.0.2, 1.1.0
• Component/s: containerization, network
• Labels: isolation networking
• Assignee: Avinash Sridharan
• Reporter: Greg Mann
• Shepherd: Jie Yu
• Created: 28/Sep/16 23:14
• Updated: 26/Apr/17 16:53
• Resolved: 29/Sep/16 01:26

Description

Launching a nested CNI-enabled container yielded the following agent log output:

cni.cpp:1255] Got assigned IPv4 address '9.0.1.25/25' from CNI network 'dcos' for container 7c1ef3c4-ba7b-4b43-ba33-0612d84100cc

indicating that the container was successfully assigned an IP. Running ifconfig -a inside the container yields:

eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1420
        inet 9.0.1.25  netmask 255.255.255.128  broadcast 0.0.0.0
        inet6 fe80::e004:4bff:fefc:6816  prefixlen 64  scopeid 0x20<link>
        ether 0a:58:09:00:01:19  txqueuelen 0  (Ethernet)
        RX packets 31  bytes 5052 (4.9 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 36  bytes 5689 (5.5 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

lo: flags=8<LOOPBACK>  mtu 65536
        loop  txqueuelen 1  (Local Loopback)
        RX packets 0  bytes 0 (0.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 0  bytes 0 (0.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

it can be seen that the loopback interface is not activated. ifconfig lo up must be run before a process within the container can bind to that interface, but this should be handled by the CNI isolator.