I'm marking this bug as Invalid the test-case specified is working in
upstream cloud-init as well as existing Ubuntu instances with cloud-
init. I believe this issue observed is an Amazon Linux specific issue
and should be handled in the Amazon Linux forum. If you feel there
still remains an upstream or Ubuntu-specific cloud-init issue, please
re-open with further details.
** Changed in: cloud-init
Status: Incomplete => Invalid
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https://bugs.launchpad.net/bugs/1672833
Title:
AWS NVME SSD (i3 family) ephemeral storage fails to mount via fs_setup
Status in cloud-init:
Invalid
Bug description:
I launched an AWS `i3.large` instance and attempted to configure it's
NVME SSD ephemeral storage via fs_setup like so:
fs_setup:
- label: nvme0n1
filesystem: ext4
extra_opts: ["-E", "nodiscard"]
device: /dev/nvme0n1
partition: auto
mounts:
- [ /dev/nvme0n1, "/media/nvme0n1", "ext4", "defaults,discard", "0", "2" ]
I also attempted to manually add a full volume partition using
disk_store, but that did not change the error output below.
The above configuration failed with the following messages in
/var/log/cloud-init.log, leading to the ephemeral storage device provided by
the 'i3' family not being mounted at the requested path:
Mar 14 15:25:53 cloud-init[2718]: helpers.py[DEBUG]: Running config-mounts
using lock (<FileLock using file
'/var/lib/cloud/instances/i-0305fb6a917397bf8/sem/config_mounts'>)
Mar 14 15:25:53 cloud-init[2718]: cc_mounts.py[DEBUG]: Attempting to
determine the real name of /dev/nvme0n1
Mar 14 15:25:53 cloud-init[2718]: cc_mounts.py[DEBUG]: Ignoring nonexistent
named mount /dev/nvme0n1
Mar 14 15:25:53 cloud-init[2718]: cc_mounts.py[DEBUG]: changed /dev/nvme0n1
=> None
The block device for these instance types (i3 family) are automatically
mapped to /dev/nvme0n1 [1] and is visible via `sudo fdisk -l` run from the
machine after boot:
Disk /dev/nvme0n1: 475.0 GB, 475000000000 bytes, 927734375 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
However, it appears that for these instance types, while the device is
automatically made visible, it is not added to the EC2 instance
metadata:
[root@ip-10-0-1-247 ec2-user]# curl
http://169.254.169.254/latest/meta-data/block-device-mapping/
ami
ebs1
...which is what fs_setup and disk_setup use to get the list of valid device
names to perform operations on:
https://git.launchpad.net/cloud-
init/tree/cloudinit/sources/DataSourceEc2.py#n164
It appears that fs_setup and disk_setup only consider devices provided by the
instance metadata, as evidenced by the code path here:
https://git.launchpad.net/cloud-init/tree/cloudinit/config/cc_disk_setup.py#n144
https://git.launchpad.net/cloud-init/tree/cloudinit/cloud.py#n84
which is no longer a valid strategy for mounting ephemeral instance
storage via cloud-config.
Note that after instance launch I was able to manually create the partition
table and a full volume primary partition (at /dev/nvme0n1p1), then create a
filesystem via 'sudo mkfs.ext4 /dev/nvme0n1p1', then finally mount the correct
disk at '/media/nvme0n1p1' via 'mount'. As a workaround to the issue above,
I'll simply run these commands manually via the 'runcmd' option in cloud-config.
**[1] The AWS documentation for the block device mappings states here:
http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/block-device-mapping-concepts.html
that "[NVMe instance store volumes] These volumes are mapped automatically as
/dev/nvme[0-7]n1. You do not need to specify the NVMe volumes supported by an
instance type in a block device mapping." This means they do not follow the
standard 'ephemeral<number>' virtual name mapping that other instances use.
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