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|description=Nova instances can be booted from volume, analogous to EBS-backed volumes in EC2.
|description=Nova instances can be booted from volume, analogous to EBS-backed volumes in EC2.


We construct a bootable volume, fire up an instance backed by this volume, and then create a snapshot image of the volume-backed instance.
We construct a bootable volume, then fire up an instance backed by this volume.


|setup=
|setup=
We assume that an instance has already been booted in a previous test, and we use this as a builder to facilitate the creation of a bootable volume.
We assume that an instance has already been booted in the previous test case, and we use this as a builder to facilitate the creation of a bootable volume.


Capture the instance name as an environment variable:
We also need a bootable image, which may be download from:


  INSTANCE=<your instance name>
$> wget https://launchpadlibrarian.net/83305348/cirros-0.3.0-x86_64-disk.img


We also need a rootfs-style image, which may be download from:
Finally, we assume that the nova-volume service or cinder is enabled and running.


  $> wget http://images.ansolabs.com/cirros-0.3.0-x86_64-rootfs.img.gz
|actions=
 
Upload the image to glance:


|actions=
$> glance add name=cirros_boot is_public=true disk_format=qcow2 container_format=bare < ./cirros-0.3.0-x86_64-disk.img
$> <nowiki>IMAGE_ID=$(glance image-list | awk '/cirros-boot/ {print $2}')</nowiki>


Create a 1Gb volume, which we will make bootable:
Create a 1Gb volume, which we will make bootable:


  $> nova volume-create --display_name=bootable_volume 1
$> cinder create --image-id $IMAGE_ID --display_name=bootable_cirros 1
  $> <nowiki>VOLUME_ID=$(nova volume-list | awk '/bootable_volume/ {print $2}')</nowiki>
$> <nowiki>VOLUME_ID=$(cinder list | awk '/bootable_cirros/ {print $2}')</nowiki>


and wait for the volume to become available:
and wait for the volume to become available:


  $> <nowiki>watch "nova volume-show bootable_volume | grep status"</nowiki>
$> <nowiki>watch "cinder show bootable_cirros | grep status"</nowiki>
 
Temporarily attach volume to your builder instance, this will allow us to copy image data into the volume
 
  $> nova volume-attach $INSTANCE $VOLUME_ID /dev/vdb
 
Wait for the volume status to show as in-use:
 
  $> <nowiki>watch "nova volume-show bootable_volume | grep status"</nowiki>
 
Format and mount volume to a staging mount point:
 
  $> ssh -o StrictHostKeyChecking=no cirros@10.0.0.2 << EOF
  set -o errexit
  set -o xtrace
  sudo mkdir -p /tmp/stage
  sudo mkfs.ext3 -b 1024 /dev/vdb 1048576
  sudo mount /dev/vdb /tmp/stage
  sudo touch /tmp/stage/cirros-0.3.0-x86_64-rootfs.img.gz
  sudo chown cirros /tmp/stage/cirros-0.3.0-x86_64-rootfs.img.gz
  EOF
 
Copy image to the staging directory on the builder instance:
 
  $> scp -o StrictHostKeyChecking=no cirros-0.3.0-x86_64-rootfs.img.gz cirros@10.0.0.2:/tmp/stage
 
Unpack image into the volume (don't worry about an unmount failure).
 
  $> ssh -o StrictHostKeyChecking=no -i $KEY_FILE cirros@10.0.0.2 << EOF
  set -o errexit
  set -o xtrace
  cd /tmp/stage
  sudo mkdir -p /tmp/cirros
  sudo gunzip cirros-0.3.0-x86_64-rootfs.img.gz
  sudo mount cirros-0.3.0-x86_64-rootfs.img /tmp/cirros
  sudo cp -pr /tmp/cirros/* /tmp/stage/
  cd
  sync
  sudo umount /tmp/cirros
  <nowiki>sudo umount /tmp/stage || true</nowiki>
  EOF
 
Detach volume for the builder instance:
 
  $> nova volume-detach $INSTANCE $VOLUME_ID
 
and wait for the volume status to show as availble:
 
  $> <nowiki>watch "nova volume-show bootable_volume | grep status"</nowiki>


Now snapshot the bootable volume we just created:
Now snapshot the bootable volume we just created:


  $> nova volume-snapshot-create --display_name bootable_snapshot $VOLUME_ID
$> cinder snapshot-create --display_name bootable_snapshot $VOLUME_ID


and wait for the snapshot to become available:
and wait for the snapshot to become available:


  $> nova volume-snapshot-show bootable_snapshot
$> watch "cinder snapshot-show bootable_snapshot"
  $> <nowiki>SNAPSHOT_ID=$(nova volume-snapshot-list | awk '/bootable_snapshot/ {print $2}')</nowiki>
$> <nowiki>SNAPSHOT_ID=$(cinder snapshot-list | awk '/bootable_snapshot/ {print $2}')</nowiki>
 
Now we can boot from the bootable volume. We use the same image as the builder instance but that is only in order to retrieve the image properties (kernel and ramdisk IDs)
 
  $> <nowiki>IMAGE_ID=$(nova show $INSTANCE | awk '/image/ {print $5}' | sed 's,(\(.*\)),\1,')</nowiki>
  $> nova boot --flavor 1 --image $INSTANCE --block_device_mapping vda=${SNAPSHOT_ID}:snap::0 volume_backed
 
Create an image fromt he running instance:
 
  $> nova image-create volume_backed volume_backed_image


Boot the image created from the running volume-backed instance:
Now we can boot from the bootable volume. We use the same image as the builder instance, but that is only in order to retrieve the image properties.


  $> <nowiki>nova boot --flavor 1 --image $(glance image-list | awk '/volume_backed_image/ {print $2}') from_volume_backed</nowiki>
$> nova boot --flavor 1 --block_device_mapping vda=${SNAPSHOT_ID}:snap::0 --key_name nova_key volume_backed


|results=
|results=


You should be able able to shh into both volume-backed instances.
You should be able able to ssh into the volume-backed instance.
 
Note the properties on the new image:
 
  $> glance image-show <nowiki>$(glance image-list | awk '/volume_backed_image/ {print $2}')</nowiki>
 
and the lack of image data (as that is taken from the volume snapshot).
 
Note also that the EC2 API reports the image as being EBS-backed as opposed to instance-store:
 
  $> euca-describe-images
 
Note that an additional snapshot now exists to back the image:
 
  $> nova volume-snapshot-list


Also note for each of the two volume-backed instances you've fired up, there is a volume cloned from the corresponding snapshot:
Also note that for the volume-backed instance you've fired up, there is a volume cloned from the corresponding snapshot:


  $> nova volume-list
$> cinder list


}}
}}

Latest revision as of 16:26, 2 April 2013

Description

Nova instances can be booted from volume, analogous to EBS-backed volumes in EC2.

We construct a bootable volume, then fire up an instance backed by this volume.

Setup

We assume that an instance has already been booted in the previous test case, and we use this as a builder to facilitate the creation of a bootable volume.

We also need a bootable image, which may be download from: 

$> wget https://launchpadlibrarian.net/83305348/cirros-0.3.0-x86_64-disk.img

Finally, we assume that the nova-volume service or cinder is enabled and running.

How to test

Upload the image to glance: 

$> glance add name=cirros_boot is_public=true disk_format=qcow2 container_format=bare < ./cirros-0.3.0-x86_64-disk.img
$> IMAGE_ID=$(glance image-list | awk '/cirros-boot/ {print $2}')

Create a 1Gb volume, which we will make bootable: 

$> cinder create --image-id $IMAGE_ID --display_name=bootable_cirros 1
$> VOLUME_ID=$(cinder list | awk '/bootable_cirros/ {print $2}')

and wait for the volume to become available: 

$> watch "cinder show bootable_cirros | grep status"

Now snapshot the bootable volume we just created: 

$> cinder snapshot-create --display_name bootable_snapshot $VOLUME_ID

and wait for the snapshot to become available: 

$> watch "cinder snapshot-show bootable_snapshot"
$> SNAPSHOT_ID=$(cinder snapshot-list | awk '/bootable_snapshot/ {print $2}')

Now we can boot from the bootable volume. We use the same image as the builder instance, but that is only in order to retrieve the image properties. 

$> nova boot --flavor 1 --block_device_mapping vda=${SNAPSHOT_ID}:snap::0 --key_name nova_key volume_backed

Expected Results

You should be able able to ssh into the volume-backed instance.

Also note that for the volume-backed instance you've fired up, there is a volume cloned from the corresponding snapshot: 

$> cinder list


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