Formatting a Disk With AWS Cloud Init

Question

I am trying to format some EBS volumes on an AWS EC2 instance by supplying user data to the cloud-init program. I would prefer to use the shell script format, not the YAML-based cloud config format. Here is my current user data script:

#!/bin/bash

# Format EBS volumes
yum install -y xfsprogs
parted /dev/sdb mktable gpt
parted -a optimal /dev/sdb mkpart primary xfs 0% 100%
parted /dev/sdb name 1 p4db
mkfs -t xfs /dev/sdb1
xfs_admin -L p4db /dev/sdb1

where /dev/sdb refers to an EBS volume attached using the launch wizard. Here is the log output from /var/log/cloud-init-output.log:

Information: You may need to update /etc/fstab.

Information: You may need to update /etc/fstab.

/dev/sdb1: No such file or directory
Usage: mkfs.xfs
/* blocksize */         [-b log=n|size=num]
/* metadata */          [-m crc=0|1,finobt=0|1]
/* data subvol */       [-d agcount=n,agsize=n,file,name=xxx,size=num,
                            (sunit=value,swidth=value|su=num,sw=num|noalign),
                            sectlog=n|sectsize=num
/* force overwrite */   [-f]
/* inode size */        [-i log=n|perblock=n|size=num,maxpct=n,attr=0|1|2,
                            projid32bit=0|1]
/* no discard */        [-K]
/* log subvol */        [-l agnum=n,internal,size=num,logdev=xxx,version=n
                            sunit=value|su=num,sectlog=n|sectsize=num,
                            lazy-count=0|1]
/* label */             [-L label (maximum 12 characters)]
/* naming */            [-n log=n|size=num,version=2|ci,ftype=0|1]
/* no-op info only */   [-N]
/* prototype file */    [-p fname]
/* quiet */             [-q]
/* realtime subvol */   [-r extsize=num,size=num,rtdev=xxx]
/* sectorsize */        [-s log=n|size=num]
/* version */           [-V]
                        devicename
<devicename> is required unless -d name=xxx is given.
<num> is xxx (bytes), xxxs (sectors), xxxb (fs blocks), xxxk (xxx KiB),
      xxxm (xxx MiB), xxxg (xxx GiB), xxxt (xxx TiB) or xxxp (xxx PiB).
<value> is xxx (512 byte blocks).

/dev/sdb1: No such file or directory

fatal error -- couldn't initialize XFS library
Sep 09 18:40:58 cloud-init[2518]: util.py[WARNING]: Failed running /var/lib/cloud/instance/scripts/part-001 [1]
Sep 09 18:40:58 cloud-init[2518]: cc_scripts_user.py[WARNING]: Failed to run module scripts-user (scripts in /var/lib/cloud/instance/scripts)
Sep 09 18:40:58 cloud-init[2518]: util.py[WARNING]: Running module scripts-user (<module 'cloudinit.config.cc_scripts_user' from '/usr/lib/python2.7/dist-packages/cloudinit/config/cc_scripts_user.pyc'>) failed
Cloud-init v. 0.7.6 finished at Fri, 09 Sep 2016 18:40:58 +0000. Datasource DataSourceEc2.  Up 145.89 seconds

So apparently, all of the calls to parted are working just fine, but the calls to mkfs ( mkfs.xfs ) and xfs_admin are not. How is parted able to format my /dev/sdb drive without issue but the XFS programs think that it doesn't exist? How can I correctly partition and format a drive using the cloud init shell format? Any insights are much appreciated!

Answer 1

Thanks to @Vorsprung's comment, I realized that the issue was in the calls to parted ). This command was expecting user feedback, which of course is not allowed during cloud-init. By adding the -s option to my parted calls, everything works fine :)