Create raid0 LVM on EC2 ephemeral storage with Ansible.

lvm-raid-ephemeral.yaml

---
# Create a RAID0 LVM through all ephemeral devices and mounts it.
- hosts: all
  gather_facts: false
  become: true
  tasks:
      - apt: name=lvm2 state=present

      # On ubuntu, sometimes first ephemeral is already mounted in /mnt.
      - mount: name=/mnt src=/dev/xvdb fstype=ext4 state=absent

      - name: Loading list of devices
        uri:
          url: "http://169.254.169.254/2016-06-30/meta-data/block-device-mapping/"
          return_content: yes
        register: devices

      - name: Load ephemeral device names
        uri:
          url: "http://169.254.169.254/2016-06-30/meta-data/block-device-mapping/{{item}}"
          return_content: yes
        with_items: "{{devices.content.split('\n')}}"
        when: item.startswith('ephemeral')
        register: device_names

      - name: Create list of device names
        set_fact:
            ephs: "{{ device_names.results | selectattr('content', 'defined') | map(attribute='content') | map('regex_replace', '^sd', '/dev/xvd') | list }}"

      - name: Create volume group
        lvg: vg=vg.eph pvs="{{ephs | join(',')}}" state=present

      - name: Create logical volume
        lvol: vg=vg.eph lv=eph size=100%VG state=present opts="-i{{ephs | length}}"

      - name: Format logical volume
        filesystem: fstype=ext4 dev=/dev/vg.eph/eph

      - name: Mount logical volume
        mount: name=/mnt src=/dev/vg.eph/eph fstype=ext4 state=mounted

It's not an efficient solution I can guess. Line 14 doesn't return some of the volumes which are attached to EC2. Similar issue as reported here - https://stackoverflow.com/questions/49891037/retrieve-correct-amazon-attached-ebs-device-from-instance-metadata-endpoint