Add block storage to shade's firstapp tutorial
(df) Edits for clarity. Change-Id: Ic31aea856ee2e9ff06ca07438d6a01c9bf8955f6
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Caleb Boylan
Diane Fleming
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firstapp/samples/shade/block_storage.py
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firstapp/samples/shade/block_storage.py
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# step-1
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import shade
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conn = shade.openstack_cloud(cloud='myfavoriteopenstack')
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# step-2
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volume = conn.create_volume(size=1, display_name='test')
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# step-3
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volumes = conn.list_volumes()
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for vol in volumes:
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print(vol)
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# step-4
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db_group = conn.create_security_group('database', 'for database service')
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conn.create_security_group_rule(db_group['name'], 3306, 3306, 'TCP')
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instance = conn.create_server(wait=True, auto_ip=False,
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name=name,
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image=image['id'],
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flavor=flavor['id'],
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security_groups=[db_group['name']])
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# step-5
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conn.attach_volume(instance, volume, '/dev/vdb')
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# step-6
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conn.detach_volume(instance, volume)
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conn.delete_volume(volume['id'])
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# step-7
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# step-8
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@ -5,42 +5,35 @@ Block Storage
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.. todo:: (For nick: Restructure the introduction to this chapter to
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provide context of what we're actually going to do.)
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By default, data in OpenStack instances is stored on 'ephemeral'
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disks. These stay with the instance throughout its lifetime, but when
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the instance is terminated, that storage disappears -- along with all
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the data stored on it. Ephemeral storage is allocated to a single
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instance and cannot be moved to another instance.
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By default, data in OpenStack instances is stored on 'ephemeral' disks. These
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disks stay with the instance throughout its lifetime, but when the instance is
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terminated, that storage and all the data stored on it disappears. Ephemeral
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storage is allocated to a single instance and cannot be moved to another
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instance.
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In this section, we will introduce block storage. Block storage
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(sometimes referred to as volume storage) provides you with access to
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persistent storage devices. You interact with block storage by
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attaching volumes to running instances, just as you might attach a USB
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drive to a physical server. Volumes can be detached from one instance
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and re-attached to another, and the data remains intact. Block
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storage is implemented in OpenStack by the OpenStack Block Storage
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(cinder) project.
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This section introduces block storage, also known as volume storage, which
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provides access to persistent storage devices. You interact with block storage
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by attaching volumes to running instances just as you might attach a USB drive
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to a physical server. You can detach volumes from one instance and reattach
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them to another instance and the data remains intact. The OpenStack Block
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Storage (cinder) project implements block storage.
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One component of the Fractal app that cannot be allowed to fail is the
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database server, which is used to keep track of all of the data about
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fractals that have been created, including their storage location. So
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while you may have configured the images to be stored in Object
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Storage in the previous section, without the database we lose track of
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where in Object Storage they are, and the parameters that were used to
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create them.
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Though you might have configured Object Storage to store images, the Fractal
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application needs a database to track the location of and parameters that were
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used to create images in Object Storage. This database server cannot fail.
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Advanced users should consider how to remove the database from the
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architecture altogether and replace it with metadata in the Object
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Storage (then contribute these steps to :doc:`craziness`). Others
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should read on to learn about how to work with block storage and move
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the Fractal app database server to use it.
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If you are an advanced user, consider how you might remove the database from
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the architecture and replace it with Object Storage metadata (then contribute
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these steps to :doc:`craziness`). Other users can continue reading to learn
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how to work with block storage and move the Fractal application database
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server to use it.
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Basics
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~~~~~~
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Later on, we'll use a volume from the block storage service to provide
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persistent storage for the Fractal app's database server, but first -
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let's cover the basics, such as creating and attaching a block storage
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device.
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Later on, we'll use a Block Storage volume to provide persistent storage for
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the database server for the Fractal application. But first, learn how to
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create and attach a Block Storage device.
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.. only:: dotnet
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@ -91,6 +84,12 @@ As always, connect to the API endpoint:
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ex_tenant_name=project_name,
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ex_force_service_region=region_name)
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.. only:: shade
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.. literalinclude:: ../samples/shade/block_storage.py
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:language: python
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:start-after: step-1
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:end-before: step-2
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To try it out, make a 1GB volume called :test'.
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@ -105,7 +104,14 @@ To try it out, make a 1GB volume called :test'.
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<StorageVolume id=755ab026-b5f2-4f53-b34a-6d082fb36689 size=1 driver=OpenStack>
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.. note:: The parameter :code:`size` is in GigaBytes.
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.. only:: shade
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.. literalinclude:: ../samples/shade/block_storage.py
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:language: python
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:start-after: step-2
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:end-before: step-3
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.. note:: The parameter :code:`size` is in gigabytes.
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List all volumes to see if it was successful:
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@ -120,18 +126,24 @@ List all volumes to see if it was successful:
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[<StorageVolume id=755ab026-b5f2-4f53-b34a-6d082fb36689 size=1 driver=OpenStack>]
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Now that you have created a storage volume, let's attach it to an
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already running instance.
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.. only:: shade
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.. literalinclude:: ../samples/shade/block_storage.py
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:language: python
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:start-after: step-3
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:end-before: step-4
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Using Block Storage for the Fractal database server
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Attach the storage volume to a running instance.
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Firstly, we're going to need a new server for our dedicated database.
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Start a new instance called :code:`app-database` using the image, flavor
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and keypair you have been using since :doc:`/getting_started`.
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We will also need a new security group to allow access to the database server
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(for mysql, port 3306) from the network:
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Use Block Storage for the Fractal database server
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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You need a server for the dedicated database. Use the image, flavor, and
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keypair that you used in :doc:`/getting_started` to launch an
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:code:`app-database` instance.
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You also need a security group to permit access to the database server (for
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MySQL, port 3306) from the network:
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.. only:: libcloud
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@ -145,9 +157,16 @@ We will also need a new security group to allow access to the database server
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ex_keyname=keypair_name,
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ex_security_groups=[db_group])
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Using the unique identifier (UUID) for the volume, make a new volume
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object, then use the server object from the previous snippet and
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attach the volume to it at :code:`/dev/vdb`:
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.. only:: shade
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.. literalinclude:: ../samples/shade/block_storage.py
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:language: python
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:start-after: step-4
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:end-before: step-5
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Create a volume object by using the unique identifier (UUID) for the volume.
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Then, use the server object from the previous code snippet to attach the
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volume to it at :code:`/dev/vdb`:
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.. only:: libcloud
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@ -156,10 +175,17 @@ attach the volume to it at :code:`/dev/vdb`:
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volume = connection.ex_get_volume('755ab026-b5f2-4f53-b34a-6d082fb36689')
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connection.attach_volume(instance, volume, '/dev/vdb')
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Log in to the server to be able to run the following steps.
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.. only:: shade
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.. literalinclude:: ../samples/shade/block_storage.py
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:language: python
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:start-after: step-5
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:end-before: step-6
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Log in to the server to run the following steps.
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.. note:: Replace :code:`IP_SERVICES` with the IP address of the
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services instance and USERNAME to the appropriate username.
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services instance and USERNAME to the appropriate user name.
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Now prepare the empty block device.
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@ -173,17 +199,17 @@ Now prepare the empty block device.
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.. todo:: Outputs missing, add attaching log from dmesg.
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Stop the running MySQL database service and move the database files
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from :file:`/var/lib/mysql` onto the new volume (temporary mounted at
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:file:`/mnt/database`).
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Stop the running MySQL database service and move the database files from
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:file:`/var/lib/mysql` to the new volume, which is temporarily mounted at
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:file:`/mnt/database`.
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::
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# systemctl stop mariadb
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# mv /var/lib/mysql/* /mnt/database
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Sync the filesystems and mount the new blockdevice now containing the
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database files to :file:`/var/lib/mysql`.
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Sync the file systems and mount the block device that contains the database
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files to :file:`/var/lib/mysql`.
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::
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@ -193,8 +219,8 @@ database files to :file:`/var/lib/mysql`.
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# echo "/dev/vdb /var/lib/mysql ext4 defaults 1 2" >> /etc/fstab
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# mount /var/lib/mysql
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Finally start the previously stopped MySQL database service and check
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if everything is working like expected.
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Finally, start the stopped MySQL database service and validate that everything
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works as expected.
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::
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@ -204,11 +230,11 @@ if everything is working like expected.
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Extras
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~~~~~~
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You can detach the volume and re-attach it elsewhere, or destroy the
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volume with the below steps.
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You can detach the volume and reattach it elsewhere, or use the following
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steps to destroy the volume.
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.. warning::
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The following operations are destructive and will result in data loss.
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The following operations are destructive and result in data loss.
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To detach and destroy a volume:
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@ -226,14 +252,20 @@ To detach and destroy a volume:
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connection.destroy_volume(volume)
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.. note:: :code:`detach_volume` and :code:`destroy_volume` take a
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volume object, not a name.
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.. note:: :code:`detach_volume` and :code:`destroy_volume` take a
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volume object, not a name.
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There are also many other useful features, such as the ability to
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create snapshots of volumes (handy for backups):
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.. only:: shade
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.. literalinclude:: ../samples/shade/block_storage.py
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:language: python
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:start-after: step-6
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:end-before: step-7
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.. only:: libcloud
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Other features, such as creating volume snapshots, are useful for backups:
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.. code-block:: python
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* snapshot_name = 'test_backup_1'
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@ -242,34 +274,32 @@ create snapshots of volumes (handy for backups):
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.. todo:: Do we need a note here to mention that 'test' is the
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volume name and not the volume object?
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You can find information about these calls and more in the
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For information about these and other calls, see
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`libcloud documentation
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<http://ci.apache.org/projects/libcloud/docs/compute/drivers/openstack.html>`_.
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Work with the OpenStack Database service
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Working with the OpenStack Database service
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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You created the database manually above, which is fine for a case with
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a single database you won't touch often like this. However, OpenStack
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also has a component code-named :code:`trove` that provides Database
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as a Service (DBaaS).
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Previously, you manually created the database, which is useful for a a single
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database that you rarely update. However, the OpenStack :code:`trove`
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component provides Database as a Service (DBaaS).
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.. note:: This OpenStack Database service is not installed in many
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clouds right now, but if your cloud does support it, it can
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clouds right now, but if your cloud supports it, it can
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make your life a lot easier when working with databases.
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SDKs don't generally support the service yet, but you can use the
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'trove' commandline client to work with it instead.
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SDKs do not generally support the service yet, but you can use the
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'trove' command-line client to work with it instead.
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Install the trove commandline client by following this guide:
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Install the trove command-line client by following this guide:
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http://docs.openstack.org/cli-reference/content/install_clients.html
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Then set up the necessary variables for your cloud in an :file:`openrc.sh` file
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using this guide:
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Then, set up necessary variables for your cloud in an :file:`openrc.sh` file
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by using this guide:
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http://docs.openstack.org/cli-reference/content/cli_openrc.html
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Ensure you have an :file:`openrc.sh` file, source it and then check
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Ensure you have an :file:`openrc.sh` file, source it, and validate that
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your trove client works: ::
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$ cat openrc.sh
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@ -284,21 +314,16 @@ your trove client works: ::
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$ trove --version
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1.0.9
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From there, you can find a good resource on what is supported and how
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to use in `these slides
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<http://www.slideshare.net/hastexo/hands-on-trove-database-as-a-service-in-openstack-33588994>`_. Steps
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to work with an existing database service installation start on
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slide 28.
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For information about supported features and how to work with an existing
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database service installation, see these
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`slides <http://www.slideshare.net/hastexo/hands-on-trove-database-as-a-service-in-openstack-33588994>`_.
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Next Steps
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Next steps
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~~~~~~~~~~
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You should now be fairly confident working with Block Storage volumes.
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There are several calls we did not cover. To see these and more, refer
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to the volume documentation of your SDK, or try a different step in
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the tutorial, including:
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You should now be fairly confident working with Block Storage volumes. For
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information about other calls, see the volume documentation for your SDK or
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try one of these tutorial steps:
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* :doc:`/orchestration`: to automatically orchestrate the application
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* :doc:`/networking`: to learn about more complex networking
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