How do I mount a persistent disk to a container volume? - google-compute-engine

Question

I'm playing around with Google's managed VM feature and finding you can fairly easily create some interesting setups. However, I have yet to figure out whether it's possible to use persistent disks to mount a volume on the container, and it seems not having this feature limits the usefulness of managed VMs for stateful containers such as databases.
So the question is: how can I mount the persistent disk that Google creates for my Compute engine instance, to a container volume?

Answer 1

Attaching a persistent disk to a Google Compute Engine instance
Follow the official persistent-disk guide:
Create a disk
Attach to an instance during instance creation, or to a running instance
Use the tool /usr/share/google/safe_format_and_mount to mount the device file /dev/disk/by-id/google-...
As noted by Faizan, use docker run -v /mnt/persistent_disk:/container/target/path to include the volume in the docker container
Referencing a persistent disk in Google Container Engine
In this method, you specify the volume declaratively (after initializing it as mentioned above...) in the Replication Controller or Pod declaration. The following is a minimal excerpt of a replication controller JSON declaration. Note that the volume has to be declared read-only because no more than two instances may write to a persistent disk at one time.
{
"id": "<id>",
"kind": "ReplicationController",
"apiVersion": "v1beta1",
"desiredState": {
"replicas": 3,
"replicaSelector": {
"name": "<id>"
},
"podTemplate": {
"desiredState": {
"manifest": {
"version": "v1beta1",
"id": "<id>",
"containers": [
{
"name": "<id>",
"image": "<docker_image>",
"volumeMounts": [
{
"name": "persistent_disk",
"mountPath": "/pd",
"readOnly": true
}
],
...
}
],
"volumes": [
{
"name": "persistent_disk",
"source": {
"persistentDisk": {
"pdName": "<persistend_disk>",
"fsType": "ext4",
"readOnly": true
}
}
}
]
}
},
"labels": {
"name": "<id>"
}
}
},
"labels": {
"name": "<id>"
}
}

Answer 2

If your persistent disk is attached and mounted already to the instance, I believe you can use it as a data volume with your docker container. I was able to find docker documentation which explains the steps on how to manage data in containers.