How to attach and mount volumes to an EC2 instance using CloudFormation

Question

I can't find a way to attach and mount volumes using cloudformation.

I can attach a volume using VolumeAttachment; however, when I do lsblk after my EC2 instance is in running state, I see this attached instances as being unmounted.

Is there a way to mount this instance from Cloudformation file? I can mount this using linux commands but would be much better to handle everything from cloudformation instead.

Here is what I've so far:

"MyEc2Instance" : {
   "Type" : "AWS::EC2::Instance",
   "Properties" : {
      "KeyName" : { "Ref" : "KeyName" }
   }
},
    "MyVolume" : {
      "Type" : "AWS::EC2::Volume",
      "Properties" : {
        "Size" : "50",
        "AvailabilityZone" : "xyz"
      }
    },
    "attachment" : {
      "Type" : "AWS::EC2::VolumeAttachment",
      "Properties" : {
        "InstanceId" : { "Ref" : "MyEc2Instance" },
        "VolumeId"  : { "Ref" : "MyVolume" },
        "Device" : "/dev/sdh"
      }
    }

And when I do lsblk on the instance, this is the result i see:

xvda    202:0    0   8G  0 disk
└─xvda1 202:1    0   8G  0 part /
xvdh    202:112  0  50G  0 disk

Notice even though I specified device name to be 'sdh' it shows attached as 'xvdh'. Why is that? And as you can see this is unmounted. How do I mount this?

Answer 1

As mentioned by helloV you will need to mount it when the instance launches using UserData. I find the new YAML format for CloudFormation templates is much easier but I've put the example in JSON too.

JSON:

"UserData"       : { "Fn::Base64" : { "Fn::Join" : ["", [
    "#!/bin/bash -xe\n",
    "# create mount point directory\n",
    "mkdir /mnt/xvdh\n",
    "# create ext4 filesystem on new volume\n",    
    "mkfs -t ext4 /dev/xvdh\n",
    "# add an entry to fstab to mount volume during boot\n",
    "echo \"/dev/xvdh       /mnt/xvdh   ext4    defaults,nofail 0       2\" >> /etc/fstab\n",
    "# mount the volume on current boot\n",
    "mount -a\n"
]]}}

YAML:

UserData:
    'Fn::Base64': !Sub
      - |
        #!/bin/bash -xe
        # create mount point directory
        mkdir /mnt/xvdh
        # create ext4 filesystem on new volume           
        mkfs -t ext4 /dev/xvdh
        # add an entry to fstab to mount volume during boot
        echo "/dev/xvdh       /mnt/xvdh   ext4    defaults,nofail 0       2" >> /etc/fstab
        # mount the volume on current boot
        mount -a