[Problem]Docker Daemon Can Not Start

Docker was running fine early.But docker daemon can not start after host server force restarting.The reason to restart the host server is docker crashed it.

]#docker ps
Cannot connect to the Docker daemon. Is ‘docker -d’ running on this host?

]#service docker status
docker dead but subsys locked

*Kernal Version:*2.6.32-573.8.1.el6.x86_64 (RHEL 6.7)

*Docker Version:*1.7.1

\nSat Nov 21 11:22:29 EST 2015\n
time=“2015-11-21T11:22:29.214558304-05:00” level=warning msg="You are running linux kernel version 2.6.32-573.8.1.el6.x86_64, which might be unstable running docker. Please upgrade your kernel to 3.10.0."
time=“2015-11-21T11:22:29.218656829-05:00” level=info msg="Listening for HTTP on unix (/var/run/docker.sock)“
time=“2015-11-21T11:22:29.249156479-05:00” level=info msg=”[graphdriver] using prior storage driver “devicemapper”"
time=“2015-11-21T11:22:29.279735164-05:00” level=warning msg="Running modprobe bridge nf_nat failed with message: install /dev/true\ninstall /sbin/modprobe --ignore-install bridge && /sbin/sysctl -q -w net.bridge.bridge-nf-call-arptables=0 net.bridge.bridge-nf-call-iptables=0 net.bridge.bridge-nf-call-ip6tables=0\ninstall /dev/true\ninsmod /lib/modules/2.6.32-573.8.1.el6.x86_64/kernel/net/bridge/bridge.ko \n, error: exit status 1"
time=“2015-11-21T11:22:29.377004507-05:00” level=fatal msg=“Error starting daemon: Error initializing network controller: Error creating default “bridge” network: package not installed”

Looks like you have a kernel version that is not supported. need 3.10+ to get everything to run properly.

From: https://docs.docker.com/engine/installation/rhel/

Docker requires a 64-bit installation regardless of your Red Hat version. Docker
requires that your kernel must be 3.10 at minimum, which Red Hat 7 runs.

To check your current kernel version, open a terminal and use uname -r to
display your kernel version:

$ uname -r

Hello Macedemo:

    Thanks for your feedback.
    I just use docker 1.7.1 which is not the latest docker version.

    And this version was running stable before I run a yum update with my OS.

    If I do not want to use Docker 1.9.

    Do I still need upgrade my kernel to 3.10?

Dear all:

    This problem has been solved.Hope the below solution can help.

    **Root Cause:**
    1.I've run "yum update" to upgrade kernel from 2.6.32-504.30.3.el6.x86_64 to 2.6.32-573.8.1.el6.x86_64.
    2.After restart the Linux host,it will start with the new kernel version 2.6.32-573
    3.Docker daemon crashed many times until can not be started after I use kernel 2.6.32-573 to run docker 1.7.1.

    1.Edit the Linux host grub.conf file to set the previous kernel version 2.6.32-504 as default one.
    2.Restart server and the docker daemon is running stable now.

   **Lesson learn:**
   1.Do not update the kernel version if docker is running on the host. 
   2.Need to confirm the version match between host kernel and docker.

Glad you got it working. And good info to know also. I see from some of my other notes that you need minimally 2.6.24 and above for containers/docker as that’s seems when cgroups was added to the kernel. I also have notes that say it was redesigned in 2013 with changes in 3.15+ kernels. Not sure but if you upgrade to newer docker you might need to upgrade kernel version also.