Docker on Google Compute Engine

docker-on-GCE.md

#Docker on GCE see:

public GCE VM, kubernettes

##Instantiate a docker VM

1. install gcutil/gcloud (see here: https://developers.google.com/compute/docs/gcutil/)
2. gcloud auth login
3. goto the page and auth...
4. Either install on a fresh VM,
5. or use the pre-installed public image:

The following steps are a an example setup, and give a flavour of the steps to go through:

e.g. VM called dockerbox

gcloud compute instances create dockerbox \
   --image container-vm-v20140710 \
   --image-project google-containers \
   --zone europe-west1-b \
   --machine-type f1-micro

Add a additional disk, here a 500GB, (will eventually house /var/lib/docker):

gcutil --project=<PROJECT-ID> adddisk container-vol --size_gb=500 --zone=europe-west1-b --disk_type=pd-standard

Attach it to the dockerbox VM

gcutil --project=secure-electron-631 attachdisk --zone=europe-west1-b --disk=container-vol,mode=read_write dockerbox

format the disk..on the instance..If your disk is listed when you run ls -l /dev/disk/by-id/* will show you the attached disks:

sudo /usr/share/google/safe_format_and_mount -m "mkfs.ext4 -F" /dev/disk/by-id/scsi-0Google_PersistentDisk_container-vol /media/container-vol

create a mount point & add to /etc/fstab (e.g. /dev/sdb in this case):

sudo mkdir /media/container-vol
sudo echo "/dev/sdb /media/container-vol ext4 defaults 1 1" sudo cat >> /etc/fstab

now mount:

sudo mount -a

create a mountpoint for the docker runtime dir & bind mount /var/lib/docker in your new 500gb disk:

sudo mkdir /media/container-vol/var/lib/docker
sudo cp /var/lib/docker /media/container-vol/var/lib/docker
sudo echo "/media/container-vol/var/lib/docker /var/lib/docker bind defaults,bind 0 0" >> /etc/fstab

##Moving the /var/lib/docker to the new disk THe path to use as the root of the Docker runtime is /var/lib/docker. We want to keep the boot disk small (only 10GB), but the /var/lib/docker will house all our containers, filesystems, images etc.. in short it will likely grow substantially. So we need to move it to the 500GB disk.

First stop the docker daemon:

docker ps -q | xargs docker kill
service docker stop

if it exists:

cd /var/lib/docker/devicemapper/mnt
umount ./*

Move the docker dir to the new disk:

dest='/media/container-vol/var/lib/docker'
mv /var/lib/docker $dest

Connect the location While you could link ln -s $dest/docker /var/lib/docker, it is better to use a bind mount see below.

Bind mount:

sudo mount -o bind /media/container-vol/var/lib/docker/ /var/lib/docker

you can also put in the fstab incase you re-start the box then it will still be mounted:

/media/container-vol/var/lib/docker/ /var/lib/docker bind defaults,bind 0 0

NOTE: if you are using a link be mindful that the device filesystem you are moving the /var/lib/docker dir supports hard and soft links! Note VirtualBox FS (vboxfs) doesn't!

modify defaults options in docker in /etc/defaults/docker so it docker daemon knows where to find the root of the docker runtime "-g option":

DOCKER_OPTS="-H 127.0.0.1:4243 -H unix:///var/run/docker.sock -r=false -g $(readlink -f /var/lib/docker)"

Lastly, restart the docker daemon… (you might need to do it a couple of times before it will say 'ok'):

sudo /etc/init.d/docker restart