Ansible EC2 ephemeral custom facter to use in software RAID and with_items

ephemeral.fact

#!/usr/bin/python

import json
import backoff
import urllib2

METADATA_URL_BASE = "http://169.254.169.254/2012-01-12/"
BLOCK_DEVICE_MAPPING = METADATA_URL_BASE + "meta-data/block-device-mapping/"

@backoff.on_exception(backoff.expo,
                        urllib2.URLError,
                        max_tries=3)
def get_http_data(resource_url):
              response = urllib2.urlopen(resource_url, timeout = 2).read()
              resp_list = []
              buff = []
              for item in response:
                  if item == '\n':
                        resp_list.append(''.join(buff))
                        buff = []
                  else:
                        buff.append(item)
              else:
                    if buff:
                       resp_list.append(''.join(buff))
              return resp_list

bd_mapping = get_http_data(BLOCK_DEVICE_MAPPING)

dout = {}
deout = {}
rdout = {}
dout['ephemerals'] = {}
deout['ephemerals_external'] = {}
rdout['ephemerals_raid'] = {}
drive_list = []

for eph in bd_mapping:
    detailed_rul = METADATA_URL_BASE + "meta-data/block-device-mapping/" + eph
    drive = get_http_data(detailed_rul)
    drive_replaced = drive[0].replace('sd', 'xvd')
    if "ephemeral" in eph:
        drive_list.append(drive_replaced)
    dout['ephemerals'][eph] = drive_replaced
deout['ephemerals_external'] = drive_list

drive_list = ["/dev/" + s for s in drive_list]
raid_drives = " ".join(drive_list)

rdout['ephemerals_raid'] = raid_drives
rdout['ephemerals_count'] = len(drive_list)

out_dict = dout.copy()
out_dict.update(deout)
out_dict.update(rdout)

print json.dumps(out_dict, indent=2)

json_additional_ephemerals.json

{
  "ephemerals_raid": "/dev/xvdb /dev/xvdc /dev/xvdd /dev/xvde /dev/xvdf /dev/xvdg /dev/xvdh /dev/xvdi",
  "ephemerals_external": [
    "xvdb",
    "xvdc",
    "xvdd",
    "xvde",
    "xvdf",
    "xvdg",
    "xvdh",
    "xvdi"
  ],
  "ephemerals_count": 8,
  "ephemerals": {
    "ami": "/dev/sda1",
    "ephemeral5": "xvdg",
    "ephemeral4": "xvdf",
    "ephemeral7": "xvdi",
    "ephemeral6": "xvdh",
    "ephemeral1": "xvdc",
    "ephemeral0": "xvdb",
    "ephemeral3": "xvde",
    "ephemeral2": "xvdd",
    "root": "/dev/sda1"
  }
}

json_no_ephemeral.json

{
  "ephemerals_raid": "",
  "ephemerals_external": [],
  "ephemerals_count": 0,
  "ephemerals": {
    "ami": "/dev/sda1",
    "root": "/dev/sda1"
  }
}

json_normal.json

{
  "ephemerals_raid": "/dev/sdb /dev/sdc",
  "ephemerals_external": [
    "sdb",
    "sdc"
  ],
  "ephemerals_count": 2,
  "ephemerals": {
    "ami": "sda1",
    "root": "/dev/sda1",
    "ephemeral1": "sdc",
    "ephemeral0": "sdb"
  }
}

mdadm_ansible_example.yml

- name: build a new RAID0 array from local drives
  shell: /bin/echo yes | /sbin/mdadm --create /dev/md0 --chunk=128 --level=0 --raid-devices={{ ansible_local.ephemeral.ephemerals_count }} {{ ansible_local.ephemeral.ephemerals_raid }} creates=/dev/md0
  when: ansible_local.ephemeral.ephemerals_count|int > 1