Terraform: Mount volume

Question

According to documentation, using terraform, I'm able to create a droplet on digital ocean:

resource "digitalocean_volume" "foobar" {
  region      = "nyc1"
  name        = "baz"
  size        = 100
  description = "an example volume"
}

So, I'm also able to add a volume to it:

resource "digitalocean_droplet" "foobar" {
  name       = "baz"
  size       = "1gb"
  image      = "coreos-stable"
  region     = "nyc1"
  volume_ids = ["${digitalocean_volume.foobar.id}"]
}

I'd like to know how to mount this on a desired location. I need to mount it automatically. I mean, when droplet is up I need to the volume is mounted. I was thinking about using chef...

Any ideas?

Answer 1

To mount the volume automatically, you can use user_data via cloud init to run a script as follow:

This is how your digitalocean_droplet resources should reflect:

resource "digitalocean_droplet" "foobar" {
  name       = "baz"
  size       = "1gb"
  image      = "coreos-stable"
  region     = "nyc1"
  volume_ids = ["${digitalocean_volume.foobar.id}"]
   # user data
  user_data = "${data.template_cloudinit_config.cloudinit-example.rendered}"
}

Then your cloud.init file that contains the cloudinit_config should be as bellow. It will reference the shell script in ${TERRAFORM_HOME}/scripts/disk.sh that would mount your volume automatically:

provider "cloudinit" {}


data "template_file" "shell-script" {
  template = "${file("scripts/disk.sh")}"
  
}
data "template_cloudinit_config" "cloudinit-example" {

  gzip = false
  base64_encode = false

  part {
    content_type = "text/x-shellscript"
    content      = "${data.template_file.shell-script.rendered}"
  }

}

The shell script to mount the volume automatically on startup is in ${TERRAFORM_HOME}/scripts/disk.sh

It will first check if a file system exist. If true it wouldn't format the disk if not it will

#!/bin/bash


DEVICE_FS=`blkid -o value -s TYPE ${DEVICE}`
if [ "`echo -n $DEVICE_FS`" == "" ] ; then
        mkfs.ext4 ${DEVICE}
fi
mkdir -p /data
echo '${DEVICE} /data ext4 defaults 0 0' >> /etc/fstab
mount /data

  

I hope this helps

Answer 2

Mounting the volume needs to be done from the guest OS itself using mount, fstab, etc.

The digital ocean docs cover this here.

Using Chef you could use resource_mount to mount it in an automated fashion.

The device name will be /dev/disk/by-id/scsi-0DO_Volume_YOUR_VOLUME_NAME. So, using the example from the Terraform docs, it would be /dev/disk/by-id/scsi-0DO_Volume_baz.