Repro cloud-init setup_fs bug

cloud-config.yml

#cloud-config
# vim: syntax=yaml

disk_setup:
  /dev/sdc:
     table_type: gpt
     layout: true
     overwrite: true

fs_setup:
  - label: etcd_disk
    filesystem: ext4
    device: /dev/sdc1
    extra_opts:
    - "-F"
    - "-E"
    - "lazy_itable_init=1,lazy_journal_init=1"

mounts:
  - - /dev/sdc1
    - /var/lib/etcddisk

cloudinit_subp_logging.patch

--- /usr/lib/python3/dist-packages/cloudinit/util.py	2017-04-03 14:04:43.000000000 +0000
+++ /usr/lib/python3/dist-packages/cloudinit/util.py	2017-05-20 05:03:03.646228392 +0000
@@ -1776,10 +1776,13 @@
 
         sp = subprocess.Popen(args, stdout=stdout,
                               stderr=stderr, stdin=stdin,
                               env=env, shell=shell)
         (out, err) = sp.communicate(data)
+        LOG.debug("out=%s", out)
+        LOG.debug("err=%s", err)
+        LOG.debug("rc=%d", sp.returncode)
 
         # Just ensure blank instead of none.
         if not out and capture:
             out = b''
         if not err and capture:

cloudinit_udevsettle_enumerate_disk.patch

--- /usr/lib/python3/dist-packages/cloudinit/config/cc_disk_setup.py	2017-04-03 14:04:43.000000000 +0000
+++ cc_disk_setup.py	2017-05-20 05:04:41.317718710 +0000
@@ -232,16 +232,18 @@
         name: the device name, i.e. sda
     """
 
     lsblk_cmd = [LSBLK_CMD, '--pairs', '--output', 'NAME,TYPE,FSTYPE,LABEL',
                  device]
+    udev_cmd = [UDEVADM_CMD, 'settle']
 
     if nodeps:
         lsblk_cmd.append('--nodeps')
 
     info = None
     try:
+        util.subp(udev_cmd)
         info, _err = util.subp(lsblk_cmd)
     except Exception as e:
         raise Exception("Failed during disk check for %s\n%s" % (device, e))
 
     parts = [x for x in (info.strip()).splitlines() if len(x.split()) > 0]

repro.sh

#!/bin/bash

[ -n "$rg" ] || ( echo "Set \$rg to the resource group name you want to use" )

echo "Creating VM"
r=$(az group create -n $rg -l westus2)
r=$(az vm create -g $rg --image UbuntuLTS -n testvm -l westus2 --custom-data cloud-config.yml --data-disk-sizes-gb 1023)
ip=$(jq <<< $r '.publicIpAddress' -r)
echo "VM is at $ip"
rm -f .knownhosts
ssh-keyscan $ip > .knownhosts 2>/dev/null
echo "First boot, saving cloud-init log as cloud-init.log.initialboot"
scp -oUserKnownHostsFile=.knownhosts $ip:/var/log/cloud-init.log cloud-init.log.initialboot
ssh -oUserKnownHostsFile=.knownhosts $ip sudo rm /var/log/cloud-init.log
echo "  creating file in /var/lib/etcddisk/:"
ssh -oUserKnownHostsFile=.knownhosts $ip sudo touch /var/lib/etcddisk/hello
ssh -oUserKnownHostsFile=.knownhosts $ip ls -al /var/lib/etcddisk/
echo "  patching util.py to increase logging of command output"
scp -oUserKnownHostsFile=.knownhosts *.patch $ip:
ssh -oUserKnownHostsFile=.knownhosts $ip sudo patch -p0 -d / <cloudinit_subp_logging.patch
echo "  rebooting"
ssh -oUserKnownHostsFile=.knownhosts $ip sudo reboot
sleep 2
time while ! ssh -oUserKnownHostsFile=.knownhosts -oConnectTimeout=1 $ip echo "reboot complete" 2>/dev/null; do true ; done
echo "After first reboot, contents of /var/lib/etcddisk/:"
ssh -oUserKnownHostsFile=.knownhosts $ip ls -al /var/lib/etcddisk/
echo "  saving cloud-init log as cloud-init.log.failreboot"
scp -oUserKnownHostsFile=.knownhosts $ip:/var/log/cloud-init.log cloud-init.log.failreboot
ssh -oUserKnownHostsFile=.knownhosts $ip sudo rm /var/log/cloud-init.log
echo "  creating file in /var/lib/etcddisk/:"
ssh -oUserKnownHostsFile=.knownhosts $ip sudo touch /var/lib/etcddisk/retry
ssh -oUserKnownHostsFile=.knownhosts $ip ls -al /var/lib/etcddisk/
echo "  patching enumerate_disk function"
ssh -oUserKnownHostsFile=.knownhosts $ip sudo patch -p0 -d / <cloudinit_udevsettle_enumerate_disk.patch
echo "  rebooting"
ssh -oUserKnownHostsFile=.knownhosts $ip sudo reboot
sleep 2
time while ! ssh -oUserKnownHostsFile=.knownhosts -oConnectTimeout=1 $ip echo "reboot complete" 2>/dev/null; do true ; done
echo "After second reboot, contents of /var/lib/etcddisk/::"
ssh -oUserKnownHostsFile=.knownhosts $ip ls -al /var/lib/etcddisk/
echo "  saving cloud-init log as cloud-init.log.successreboot"
scp -oUserKnownHostsFile=.knownhosts $ip:/var/log/cloud-init.log cloud-init.log.successreboot