Help with setting ephemeral volume on EC2

[Tzach Livyatan]

I'm struggling with adding ephemeral volume to EC2 instance on creation

Base on examples, I use the following task, but its look like its ignored with out any error message.

What am I'm doing wrong?

Thanks

    - name: Launch instances

      local_action:

        module: ec2

        region: "{{region}}"

        keypair: "{{key_name}}"

        group: "{{security_group}}"

        instance_type: "{{instance_type}}"

        image: "{{image}}"

        count: "{{cluster_nodes}}"

        volumes:

          - device_name: /dev/xvdb

            ephemeral: ephemeral0

          - device_name: /dev/xvdc

            ephemeral: ephemeral1

        wait: yes

      register: ec2_cluster

[Tzach Livyatan]

I'm using ansible 1.9.1

[Roy]

What type of instance you are using, because not all instances comes with ephemeral