fs_setup/disk_setup: option to wait for the device to exist before continuing

This bug was originally filed in Launchpad as [LP: #1832645](https://bugs.launchpad.net/cloud-init/+bug/1832645)

Launchpad details

affected_projects = []

assignee = None

assignee_name = None

date_closed = None

date_created = 2019-06-12T20:48:53.539989+00:00

date_fix_committed = None

date_fix_released = None

id = 1832645

importance = medium

is_complete = False

lp_url = https://bugs.launchpad.net/cloud-init/+bug/1832645

milestone = None

owner = minfrin-y

owner_name = Graham Leggett

private = False

status = in_progress

submitter = minfrin-y

submitter_name = Graham Leggett

tags = []

duplicates = [1907080]

_Launchpad user **Graham Leggett(minfrin-y)** wrote on 2019-06-12T20:48:53.539989+00:00_

When using the AWS::EC2::Volume and AWS::EC2::VolumeAttachment options to add a volume to an AWS::EC2::Instance on AWS EC2, the volume is not immediately available on the instance.

This causes fs_setup and disk_setup to fail.

What would prevent this failure is a "wait" option on both fs_setup and disk_setup, which if true, will cause cloud-init to wait until the device exists (caused by AWS catching up and attaching the device) before continuing.

Start by locating the fs_setup and disk_setup entry points and their existing tests, then trace how each currently handles a device that is not yet available. Done means both options can wait for the device before continuing, with tests covering delayed device attachment.

Written by the indexing model from the issue text.