Merge "FirstApp: Edits section5"
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===========================
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=============
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Section Five: Block Storage
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Block Storage
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===========================
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=============
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.. todo:: (For nick: Restructure the introduction to this chapter to provide context of what we're actually
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.. todo:: (For nick: Restructure the introduction to this chapter to
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going to do.)
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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' disks. These stay with the instance throughout its lifetime, but when the
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By default, data in OpenStack instances is stored on 'ephemeral'
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instance is terminated, that storage disappears -- along with all the data stored on it. Ephemeral storage is allocated to a
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disks. These stay with the instance throughout its lifetime, but when
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single instance and cannot be moved to another instance.
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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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In this section, we will introduce block storage. Block storage (sometimes referred to as volume storage) provides you
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In this section, we will introduce block storage. Block storage
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with access to persistent storage devices. You interact with block storage by attaching volumes
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(sometimes referred to as volume storage) provides you with access to
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to running instances, just as you might attach a USB drive to a physical server. Volumes can be detached from one instance and re-attached to another, and the data remains intact.
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persistent storage devices. You interact with block storage by
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Block storage is implemented in OpenStack by the OpenStack Block Storage (cinder) project.
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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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One component of the Fractal app that cannot be allowed to fail is the database server, which is used to keep track
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One component of the Fractal app that cannot be allowed to fail is the
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of all of the data about fractals that have been created, including their storage location. So while you may have
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database server, which is used to keep track of all of the data about
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configured the images to be stored in Object Storage in the previous section, without the database we lose track of
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fractals that have been created, including their storage location. So
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where in Object Storage they are, and the parameters that were used to create them.
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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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Advanced users should consider how to remove the database from the architecture altogether and replace it
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Advanced users should consider how to remove the database from the
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with metadata in the Object Storage (then contribute these steps to :doc:`section9`). Others should read
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architecture altogether and replace it with metadata in the Object
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on to learn about how to work with block storage and move the Fractal app database server to use it.
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Storage (then contribute these steps to :doc:`section9`). 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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Basics
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Basics
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------
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~~~~~~
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Later on, we'll use a volume from the block storage service
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Later on, we'll use a volume from the block storage service to provide
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to provide persistent storage for the Fractal app's database server,
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persistent storage for the Fractal app's database server, but first -
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but first - let's cover the basics, such as creating and attaching a block storage device.
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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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.. only:: dotnet
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.. only:: dotnet
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.. warning:: This section has not yet been completed for the .NET SDK
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.. warning:: This section has not yet been completed for the .NET SDK.
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.. only:: fog
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.. only:: fog
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.. warning:: This section has not yet been completed for the fog SDK
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.. warning:: This section has not yet been completed for the fog SDK.
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.. only:: jclouds
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.. only:: jclouds
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.. warning:: This section has not yet been completed for the jclouds SDK
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.. warning:: This section has not yet been completed for the jclouds SDK.
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.. only:: node
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.. only:: node
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.. warning:: This section has not yet been completed for the pkgcloud SDK
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.. warning:: This section has not yet been completed for the pkgcloud SDK.
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.. only:: openstacksdk
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.. only:: openstacksdk
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.. warning:: This section has not yet been completed for the OpenStack SDK
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.. warning:: This section has not yet been completed for the OpenStack SDK.
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.. only:: phpopencloud
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.. only:: phpopencloud
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.. warning:: This section has not yet been completed for the PHP-OpenCloud SDK
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.. warning:: This section has not yet been completed for the
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PHP-OpenCloud SDK.
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As always, connect to the API endpoint:
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As always, connect to the API endpoint:
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@ -107,11 +120,12 @@ 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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[<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 already running instance.
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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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Using Block Storage for the Fractal Database Server
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Using Block Storage for the Fractal database server
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---------------------------------------------------
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Firstly, we're going to need a new server for our dedicated database.
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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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Start a new instance called :code:`app-database` using the image, flavor
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@ -131,8 +145,9 @@ 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_keyname=keypair_name,
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ex_security_groups=[db_group])
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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 object, then
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Using the unique identifier (UUID) for the volume, make a new volume
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use the server object from the previous snippet and attach the volume to it at :code:`/dev/vdb`:
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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:: libcloud
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.. only:: libcloud
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@ -143,7 +158,8 @@ use the server object from the previous snippet and attach the volume to it at :
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Log in to the server to be able to run the following steps.
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Log in to the server to be able to run the following steps.
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.. note:: Replace :code:`IP_SERVICES` with the IP address of the services instance and USERNAME to the appropriate username.
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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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Now prepare the empty block device.
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Now prepare the empty block device.
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@ -157,14 +173,17 @@ Now prepare the empty block device.
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.. todo:: Outputs missing, add attaching log from dmesg.
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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 from :code:`/var/lib/mysql` onto the new volume (temporary mounted at :code:`/mnt/database`).
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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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::
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::
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# systemctl stop mariadb
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# systemctl stop mariadb
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# mv /var/lib/mysql/* /mnt/database
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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 database files to :code:`/var/lib/mysql`.
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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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::
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::
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@ -174,7 +193,8 @@ Sync the filesystems and mount the new blockdevice now containing the database f
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# echo "/dev/vdb /var/lib/mysql ext4 defaults 1 2" >> /etc/fstab
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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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# mount /var/lib/mysql
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Finally start the previously stopped MySQL database service and check if everything is working like expected.
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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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::
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::
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@ -182,9 +202,10 @@ Finally start the previously stopped MySQL database service and check if everyth
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# mysql -ufaafo -ppassword -h localhost faafo -e 'show tables;'
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# mysql -ufaafo -ppassword -h localhost faafo -e 'show tables;'
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Extras
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Extras
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------
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~~~~~~
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You can detach the volume and re-attach it elsewhere, or destroy the volume with the below steps.
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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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.. warning::
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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 will result in data loss.
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@ -205,9 +226,11 @@ To detach and destroy a volume:
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connection.destroy_volume(volume)
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connection.destroy_volume(volume)
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.. note:: :code:`detach_volume` and :code:`destroy_volume` take a 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 create snapshots of volumes (handy for backups):
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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:: libcloud
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.. only:: libcloud
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@ -216,32 +239,38 @@ There are also many other useful features, such as the ability to create snapsho
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* snapshot_name = 'test_backup_1'
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* snapshot_name = 'test_backup_1'
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connnection.create_volume_snapshot('test', name='test backup 1')
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connnection.create_volume_snapshot('test', name='test backup 1')
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.. todo:: Do we need a note here to mention that 'test' is the volume name and not the volume object?
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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 `libcloud documentation <http://ci.apache.org/projects/libcloud/docs/compute/drivers/openstack.html>`_.
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You can find information about these calls and more in the
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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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Working with the OpenStack Database service
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Working with the OpenStack Database service
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-------------------------------------------
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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You created the database manually above, which is fine for a case with a single
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You created the database manually above, which is fine for a case with
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database you won't touch often like this. However, OpenStack also has a component
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a single database you won't touch often like this. However, OpenStack
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code-named :code:`trove` that provides Database as a Service (DBaaS).
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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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.. note:: This OpenStack Database service is not installed in many clouds right now, but if your cloud does
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.. note:: This OpenStack Database service is not installed in many
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support it, it can make your life a lot easier when working with databases.
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clouds right now, but if your cloud does support 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 'trove' commandline client
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SDKs don't generally support the service yet, but you can use the
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to work with it instead.
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'trove' commandline 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 commandline client by following this guide:
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http://docs.openstack.org/cli-reference/content/install_clients.html
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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 'openrc' file using this guide:
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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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http://docs.openstack.org/cli-reference/content/cli_openrc.html
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http://docs.openstack.org/cli-reference/content/cli_openrc.html
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Ensure you have an openrc.sh file, source it and then check your trove client works:
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Ensure you have an :file:`openrc.sh` file, source it and then check
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::
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your trove client works: ::
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$ cat openrc.sh
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$ cat openrc.sh
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export OS_USERNAME=your_auth_username
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export OS_USERNAME=your_auth_username
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1.0.9
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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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From there, you can find a good resource on what is supported and how
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to use in `these slides <http://www.slideshare.net/hastexo/hands-on-trove-database-as-a-service-in-openstack-33588994>`_. Steps to work with an existing database
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to use in `these slides
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service installation start on slide 28.
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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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Next Steps
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Next Steps
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----------
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~~~~~~~~~~
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You should now be fairly confident working with Block Storage volumes.
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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,
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There are several calls we did not cover. To see these and more, refer
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refer to the volume documentation of your SDK, or try a different step in the tutorial, including:
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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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* :doc:`/section6` - to automatically orchestrate the application
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* :doc:`/section6`: to automatically orchestrate the application
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* :doc:`/section7` - to learn about more complex networking
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* :doc:`/section7`: to learn about more complex networking
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* :doc:`/section8` - for advice for developers new to operations
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* :doc:`/section8`: for advice for developers new to operations
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