All about containers

Here is the command to create a docker container by using google container image.

  docker run --rm gcr.io/google-containers/busybox

Use docker to run an interactive container from gcr

  docker run -i -t gcr.io/google-containers/busybox 

Use kubectl to run an interactive container from gcr 

  kubectl run -i -t tongbusy --image=gcr.io/google-containers/busybox

Attach to a running container in a pod.

  kubectl attach tongbusy-400598208-v0jpg -c tongbusy -i -t 

Install pypy to coreos

  wget https://bitbucket.org/squeaky/portable-pypy/downloads/pypy-5.6-linux_x86_64-portable.tar.bz2

  tar xf pypy-5.6-linux_x86_64-portable.tar.bz2 

Check coreos releases:

  cat /etc/os-release

Inspect log files of systemd server

journalctl -u [unitfile]

for example, for a service named kube-apiserver, you should do the following:

   sudo journalctl -u kube-apiserver

Other kubernetes services checking log files:

sudo journalctl -u kube-controller-manager

sudo journalctl -u kube-scheduler

sudo journalctl -u kubelet

sudo journalctl -u kube-proxy    

Get various networking related parameters by using basic bash command

vifcidr=$(ip -4 -o addr | grep -v '127.0.0.1' | awk '{print $4}’)
Find the cidr

vifbrd=$(ip -4 -o addr | grep -v '127.0.0.1' | awk '{print $6}’)
Find the broadcast address

vifmtu=$(ip -4 -o link | grep -v 'LOOPBACK' | awk '{print $5}’)
Find MTU

vifip=$(echo $vifcidr | awk -F '/' '{print $1 }')
Find IP address based on the cidr found above

vifname=$(ip -4 -o addr | grep -v '127.0.0.1' | awk '{print $2}')
Find the non-loopback interface card

defaultgw=$(ip route | awk '/default / {print $3}')
Find the default gateway ip address