546 lines
22 KiB
ReStructuredText
546 lines
22 KiB
ReStructuredText
========
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Upgrades
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========
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With the exception of Object Storage, upgrading from one version of
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OpenStack to another can take a great deal of effort. This chapter
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provides some guidance on the operational aspects that you should
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consider for performing an upgrade for an OpenStack environment.
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Pre-upgrade considerations
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~~~~~~~~~~~~~~~~~~~~~~~~~~
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Upgrade planning
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----------------
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- Thoroughly review the `release
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notes <http://releases.openstack.org/>`_ to learn
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about new, updated, and deprecated features. Find incompatibilities
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between versions.
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- Consider the impact of an upgrade to users. The upgrade process
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interrupts management of your environment including the dashboard. If
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you properly prepare for the upgrade, existing instances, networking,
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and storage should continue to operate. However, instances might
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experience intermittent network interruptions.
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- Consider the approach to upgrading your environment. You can perform
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an upgrade with operational instances, but this is a dangerous
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approach. You might consider using live migration to temporarily
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relocate instances to other compute nodes while performing upgrades.
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However, you must ensure database consistency throughout the process;
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otherwise your environment might become unstable. Also, don't forget
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to provide sufficient notice to your users, including giving them
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plenty of time to perform their own backups.
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- Consider adopting structure and options from the service
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configuration files and merging them with existing configuration
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files. The `OpenStack Configuration
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Reference <http://docs.openstack.org/newton/config-reference/>`_
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contains new, updated, and deprecated options for most services.
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- Like all major system upgrades, your upgrade could fail for one or
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more reasons. You can prepare for this situation by having the
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ability to roll back your environment to the previous release,
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including databases, configuration files, and packages. We provide an
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example process for rolling back your environment in
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:ref:`rolling_back_a_failed_upgrade`.
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- Develop an upgrade procedure and assess it thoroughly by using a test
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environment similar to your production environment.
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Pre-upgrade testing environment
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-------------------------------
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The most important step is the pre-upgrade testing. If you are upgrading
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immediately after release of a new version, undiscovered bugs might
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hinder your progress. Some deployers prefer to wait until the first
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point release is announced. However, if you have a significant
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deployment, you might follow the development and testing of the release
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to ensure that bugs for your use cases are fixed.
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Each OpenStack cloud is different even if you have a near-identical
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architecture as described in this guide. As a result, you must still
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test upgrades between versions in your environment using an approximate
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clone of your environment.
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However, that is not to say that it needs to be the same size or use
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identical hardware as the production environment. It is important to
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consider the hardware and scale of the cloud that you are upgrading. The
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following tips can help you minimise the cost:
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Use your own cloud
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The simplest place to start testing the next version of OpenStack is
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by setting up a new environment inside your own cloud. This might
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seem odd, especially the double virtualization used in running
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compute nodes. But it is a sure way to very quickly test your
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configuration.
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Use a public cloud
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Consider using a public cloud to test the scalability limits of your
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cloud controller configuration. Most public clouds bill by the hour,
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which means it can be inexpensive to perform even a test with many
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nodes.
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Make another storage endpoint on the same system
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If you use an external storage plug-in or shared file system with
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your cloud, you can test whether it works by creating a second share
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or endpoint. This allows you to test the system before entrusting
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the new version on to your storage.
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Watch the network
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Even at smaller-scale testing, look for excess network packets to
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determine whether something is going horribly wrong in
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inter-component communication.
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To set up the test environment, you can use one of several methods:
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- Do a full manual install by using the `Installation Tutorials and Guides
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<http://docs.openstack.org/project-install-guide/newton/>`_ for
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your platform. Review the final configuration files and installed
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packages.
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- Create a clone of your automated configuration infrastructure with
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changed package repository URLs.
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Alter the configuration until it works.
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Either approach is valid. Use the approach that matches your experience.
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An upgrade pre-testing system is excellent for getting the configuration
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to work. However, it is important to note that the historical use of the
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system and differences in user interaction can affect the success of
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upgrades.
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If possible, we highly recommend that you dump your production database
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tables and test the upgrade in your development environment using this
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data. Several MySQL bugs have been uncovered during database migrations
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because of slight table differences between a fresh installation and
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tables that migrated from one version to another. This will have impact
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on large real datasets, which you do not want to encounter during a
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production outage.
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Artificial scale testing can go only so far. After your cloud is
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upgraded, you must pay careful attention to the performance aspects of
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your cloud.
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Upgrade Levels
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--------------
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Upgrade levels are a feature added to OpenStack Compute since the
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Grizzly release to provide version locking on the RPC (Message Queue)
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communications between the various Compute services.
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This functionality is an important piece of the puzzle when it comes to
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live upgrades and is conceptually similar to the existing API versioning
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that allows OpenStack services of different versions to communicate
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without issue.
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Without upgrade levels, an X+1 version Compute service can receive and
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understand X version RPC messages, but it can only send out X+1 version
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RPC messages. For example, if a nova-conductor process has been upgraded
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to X+1 version, then the conductor service will be able to understand
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messages from X version nova-compute processes, but those compute
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services will not be able to understand messages sent by the conductor
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service.
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During an upgrade, operators can add configuration options to
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``nova.conf`` which lock the version of RPC messages and allow live
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upgrading of the services without interruption caused by version
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mismatch. The configuration options allow the specification of RPC
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version numbers if desired, but release name alias are also supported.
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For example:
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.. code-block:: ini
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[upgrade_levels]
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compute=X+1
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conductor=X+1
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scheduler=X+1
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will keep the RPC version locked across the specified services to the
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RPC version used in X+1. As all instances of a particular service are
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upgraded to the newer version, the corresponding line can be removed
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from ``nova.conf``.
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Using this functionality, ideally one would lock the RPC version to the
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OpenStack version being upgraded from on nova-compute nodes, to ensure
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that, for example X+1 version nova-compute processes will continue to
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work with X version nova-conductor processes while the upgrade
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completes. Once the upgrade of nova-compute processes is complete, the
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operator can move onto upgrading nova-conductor and remove the version
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locking for nova-compute in ``nova.conf``.
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Upgrade process
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~~~~~~~~~~~~~~~
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This section describes the process to upgrade a basic OpenStack
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deployment based on the basic two-node architecture in the `Installation
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Tutorials and Guides
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<http://docs.openstack.org/project-install-guide/newton/>`_. All
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nodes must run a supported distribution of Linux with a recent kernel
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and the current release packages.
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Service specific upgrade instructions
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-------------------------------------
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Refer to the following upgrade notes for information on upgrading specific
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OpenStack services:
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* `Upgrading the Networking service
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<http://docs.openstack.org/developer/neutron/devref/upgrade.html>`_
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* `Upgrading the Compute service
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<http://docs.openstack.org/developer/nova/upgrade.html>`_
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* `Upgrading the Identity service
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<http://docs.openstack.org/developer/keystone/upgrading.html>`_
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* `Upgrading the Block Storage service
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<http://docs.openstack.org/developer/cinder/upgrade.html>`_
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Prerequisites
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-------------
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- Perform some cleaning of the environment prior to starting the
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upgrade process to ensure a consistent state. For example, instances
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not fully purged from the system after deletion might cause
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indeterminate behavior.
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- For environments using the OpenStack Networking service (neutron),
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verify the release version of the database. For example:
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.. code-block:: console
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# su -s /bin/sh -c "neutron-db-manage --config-file /etc/neutron/neutron.conf \
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--config-file /etc/neutron/plugins/ml2/ml2_conf.ini current" neutron
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Perform a backup
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----------------
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#. Save the configuration files on all nodes. For example:
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.. code-block:: console
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# for i in keystone glance nova neutron openstack-dashboard cinder heat ceilometer; \
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do mkdir $i-RELEASE_NAME; \
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done
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# for i in keystone glance nova neutron openstack-dashboard cinder heat ceilometer; \
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do cp -r /etc/$i/* $i-RELEASE_NAME/; \
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done
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.. note::
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You can modify this example script on each node to handle different
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services.
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#. Make a full database backup of your production data. Since the Kilo release,
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database downgrades are not supported, and restoring from backup is the only
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method available to retrieve a previous database version.
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.. code-block:: console
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# mysqldump -u root -p --opt --add-drop-database --all-databases > RELEASE_NAME-db-backup.sql
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.. note::
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Consider updating your SQL server configuration as described in the
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`Installation Tutorials and Guides
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<http://docs.openstack.org/project-install-guide/newton/>`_.
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Manage repositories
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-------------------
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On all nodes:
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#. Remove the repository for the previous release packages.
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#. Add the repository for the new release packages.
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#. Update the repository database.
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Upgrade packages on each node
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-----------------------------
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Depending on your specific configuration, upgrading all packages might
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restart or break services supplemental to your OpenStack environment.
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For example, if you use the TGT iSCSI framework for Block Storage
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volumes and the upgrade includes new packages for it, the package
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manager might restart the TGT iSCSI services and impact connectivity to
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volumes.
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If the package manager prompts you to update configuration files, reject
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the changes. The package manager appends a suffix to newer versions of
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configuration files. Consider reviewing and adopting content from these
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files.
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.. note::
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You may need to explicitly install the ``ipset`` package if your
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distribution does not install it as a dependency.
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Update services
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---------------
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To update a service on each node, you generally modify one or more
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configuration files, stop the service, synchronize the database schema,
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and start the service. Some services require different steps. We
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recommend verifying operation of each service before proceeding to the
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next service.
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The order you should upgrade services, and any changes from the general
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upgrade process is described below:
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**Controller node**
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#. Identity service - Clear any expired tokens before synchronizing
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the database.
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#. Image service
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#. Compute service, including networking components.
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#. Networking service
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#. Block Storage service
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#. Dashboard - In typical environments, updating Dashboard only
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requires restarting the Apache HTTP service.
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#. Orchestration service
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#. Telemetry service - In typical environments, updating the
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Telemetry service only requires restarting the service.
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#. Compute service - Edit the configuration file and restart the service.
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#. Networking service - Edit the configuration file and restart the service.
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**Storage nodes**
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* Block Storage service - Updating the Block Storage service only requires
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restarting the service.
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**Compute nodes**
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* Networking service - Edit the configuration file and restart the service.
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Final steps
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-----------
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On all distributions, you must perform some final tasks to complete the
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upgrade process.
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#. Decrease DHCP timeouts by modifying the :file:`/etc/nova/nova.conf` file on
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the compute nodes back to the original value for your environment.
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#. Update all ``.ini`` files to match passwords and pipelines as required
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for the OpenStack release in your environment.
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#. After migration, users see different results from
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:command:`openstack image list` and :command:`glance image-list`. To ensure
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users see the same images in the list commands, edit the
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:file:`/etc/glance/policy.json` file and :file:`/etc/nova/policy.json` file
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to contain ``"context_is_admin": "role:admin"``, which limits access to
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private images for projects.
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#. Verify proper operation of your environment. Then, notify your users
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that their cloud is operating normally again.
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.. _rolling_back_a_failed_upgrade:
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Rolling back a failed upgrade
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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This section provides guidance for rolling back to a previous release of
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OpenStack. All distributions follow a similar procedure.
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.. warning::
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Rolling back your environment should be the final course of action
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since you are likely to lose any data added since the backup.
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A common scenario is to take down production management services in
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preparation for an upgrade, completed part of the upgrade process, and
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discovered one or more problems not encountered during testing. As a
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consequence, you must roll back your environment to the original "known
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good" state. You also made sure that you did not make any state changes
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after attempting the upgrade process; no new instances, networks,
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storage volumes, and so on. Any of these new resources will be in a
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frozen state after the databases are restored from backup.
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Within this scope, you must complete these steps to successfully roll
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back your environment:
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#. Roll back configuration files.
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#. Restore databases from backup.
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#. Roll back packages.
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You should verify that you have the requisite backups to restore.
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Rolling back upgrades is a tricky process because distributions tend to
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put much more effort into testing upgrades than downgrades. Broken
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downgrades take significantly more effort to troubleshoot and, resolve
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than broken upgrades. Only you can weigh the risks of trying to push a
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failed upgrade forward versus rolling it back. Generally, consider
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rolling back as the very last option.
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The following steps described for Ubuntu have worked on at least one
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production environment, but they might not work for all environments.
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**To perform a rollback**
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#. Stop all OpenStack services.
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#. Copy contents of configuration backup directories that you created
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during the upgrade process back to ``/etc/<service>`` directory.
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#. Restore databases from the ``RELEASE_NAME-db-backup.sql`` backup file
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that you created with the :command:`mysqldump` command during the upgrade
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process:
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.. code-block:: console
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# mysql -u root -p < RELEASE_NAME-db-backup.sql
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#. Downgrade OpenStack packages.
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.. warning::
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Downgrading packages is by far the most complicated step; it is
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highly dependent on the distribution and the overall administration
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of the system.
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#. Determine which OpenStack packages are installed on your system. Use the
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:command:`dpkg --get-selections` command. Filter for OpenStack
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packages, filter again to omit packages explicitly marked in the
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``deinstall`` state, and save the final output to a file. For example,
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the following command covers a controller node with keystone, glance,
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nova, neutron, and cinder:
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.. code-block:: console
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# dpkg --get-selections | grep -e keystone -e glance -e nova -e neutron \
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-e cinder | grep -v deinstall | tee openstack-selections
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cinder-api install
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cinder-common install
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cinder-scheduler install
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cinder-volume install
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glance install
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glance-api install
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glance-common install
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glance-registry install
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neutron-common install
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neutron-dhcp-agent install
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neutron-l3-agent install
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neutron-lbaas-agent install
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neutron-metadata-agent install
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neutron-plugin-openvswitch install
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neutron-plugin-openvswitch-agent install
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neutron-server install
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nova-api install
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nova-cert install
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nova-common install
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nova-conductor install
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nova-consoleauth install
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nova-novncproxy install
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nova-objectstore install
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nova-scheduler install
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python-cinder install
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python-cinderclient install
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python-glance install
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python-glanceclient install
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python-keystone install
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python-keystoneclient install
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python-neutron install
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python-neutronclient install
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python-nova install
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python-novaclient install
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.. note::
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Depending on the type of server, the contents and order of your
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package list might vary from this example.
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#. You can determine the package versions available for reversion by using
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the ``apt-cache policy`` command. For example:
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.. code-block:: console
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# apt-cache policy nova-common
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nova-common:
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Installed: 2:14.0.1-0ubuntu1~cloud0
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Candidate: 2:14.0.1-0ubuntu1~cloud0
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Version table:
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*** 2:14.0.1-0ubuntu1~cloud0 500
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500 http://ubuntu-cloud.archive.canonical.com/ubuntu xenial-updates/newton/main amd64 Packages
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100 /var/lib/dpkg/status
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2:13.1.2-0ubuntu2 500
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500 http://archive.ubuntu.com/ubuntu xenial-updates/main amd64 Packages
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2:13.0.0-0ubuntu2 500
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500 http://archive.ubuntu.com/ubuntu xenial/main amd64 Packages
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.. note::
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If you removed the release repositories, you must first reinstall
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them and run the :command:`apt-get update` command.
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The command output lists the currently installed version of the package,
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newest candidate version, and all versions along with the repository that
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contains each version. Look for the appropriate release
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version— ``2:14.0.1-0ubuntu1~cloud0`` in this case. The process of
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manually picking through this list of packages is rather tedious and
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prone to errors. You should consider using a script to help
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with this process. For example:
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.. code-block:: console
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# for i in `cut -f 1 openstack-selections | sed 's/neutron/;'`;
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do echo -n $i ;apt-cache policy $i | grep -B 1 RELEASE_NAME |
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grep -v Packages | awk '{print "="$1}';done | tr '\n' ' ' |
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tee openstack-RELEASE_NAME-versions
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cinder-api=2:9.0.0-0ubuntu1~cloud0
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cinder-common=2:9.0.0-0ubuntu1~cloud0
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cinder-scheduler=2:9.0.0-0ubuntu1~cloud0
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cinder-volume=2:9.0.0-0ubuntu1~cloud0
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glance=2:13.0.0-0ubuntu1~cloud0
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glance-api=2:13.0.0-0ubuntu1~cloud0 500
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glance-common=2:13.0.0-0ubuntu1~cloud0 500
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glance-registry=2:13.0.0-0ubuntu1~cloud0 500
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neutron-common=2:9.0.0-0ubuntu1~cloud0
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neutron-dhcp-agent=2:9.0.0-0ubuntu1~cloud0
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neutron-l3-agent=2:9.0.0-0ubuntu1~cloud0
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neutron-lbaas-agent=2:9.0.0-0ubuntu1~cloud0
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neutron-metadata-agent=2:9.0.0-0ubuntu1~cloud0
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neutron-server=2:9.0.0-0ubuntu1~cloud0
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nova-api=2:14.0.1-0ubuntu1~cloud0
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nova-cert=2:14.0.1-0ubuntu1~cloud0
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nova-common=2:14.0.1-0ubuntu1~cloud0
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nova-conductor=2:14.0.1-0ubuntu1~cloud0
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nova-consoleauth=2:14.0.1-0ubuntu1~cloud0
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nova-novncproxy=2:14.0.1-0ubuntu1~cloud0
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nova-objectstore=2:14.0.1-0ubuntu1~cloud0
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nova-scheduler=2:14.0.1-0ubuntu1~cloud0
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python-cinder=2:9.0.0-0ubuntu1~cloud0
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python-cinderclient=1:1.9.0-0ubuntu1~cloud0
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python-glance=2:13.0.0-0ubuntu1~cloud0
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|
python-glanceclient=1:2.5.0-0ubuntu1~cloud0
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|
python-neutron=2:9.0.0-0ubuntu1~cloud0
|
|
python-neutronclient=1:6.0.0-0ubuntu1~cloud0
|
|
python-nova=2:14.0.1-0ubuntu1~cloud0
|
|
python-novaclient=2:6.0.0-0ubuntu1~cloud0
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python-openstackclient=3.2.0-0ubuntu2~cloud0
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|
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#. Use the :command:`apt-get install` command to install specific versions
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|
of each package by specifying ``<package-name>=<version>``. The script in
|
|
the previous step conveniently created a list of ``package=version``
|
|
pairs for you:
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|
|
|
.. code-block:: console
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|
|
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# apt-get install `cat openstack-RELEASE_NAME-versions`
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|
|
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This step completes the rollback procedure. You should remove the
|
|
upgrade release repository and run :command:`apt-get update` to prevent
|
|
accidental upgrades until you solve whatever issue caused you to roll
|
|
back your environment.
|