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Upgrade Overview
Overview
Upgrading Mirantis OpenStack from version 6.1 to version 7.0 involves building new environment, installing an HA Controller node in that environment, alongside with the old Controller nodes, switching all compute nodes to the new controller nodes, and then upgrading the Compute nodes.
You do not need any new hardware for the upgrade.
Warning
During the upgrade it virtual machines and other resources might experience temporary network disconnects. Schedule the upgrade during maintenance window.
Upgrade Scenario
The proposed solution includes the following general steps described below in more details:
- OpenStack environment of version 7.0 is created using Fuel API with the settings and network configurations matching the configuration of the original 6.1 environment.
- One of the
Cloud Infrastructure Controllers <cic-term>(CICs) in the original 6.1 environment is deleted and moved to the 6.1 environment. It is then installed in that environment as a primary controller side-by-side with the original 6.1 environment. - All OpenStack platform services are put into
Maintenance Mode <db-backup-ops>for the whole duration of the upgrade procedure to prevent user data loss and/or corruption. - Copy the state databases of all the upgradeable OpenStack components to the new Controller and upgrade these wuth the standard ‘database migration’ feature of OpenStack.
- Reconfigure the Ceph cluster in such a way that the Monitors on the new 7.0 CICs replace the Monitors of the 6.1 environment, retaining the original IP addresses and configuration parameters.
- The 7.0 CIC is connected to the Management and External networks,
while the original 6.1 ones are disconnected. The 7.0 CIC takes over
Virtual IPs in the Management and Public
networks <logical-networks-arch>. - Control plane services on the Compute nodes in the 6.1 environment are upgraded to 7.0 without affecting the virtual server instances and workloads. After the upgrade, the Compute service reconnects to 7.0 CICs.
- Compute nodes from the 6.1 environment work with the CICs from the 7.0 environment, forming a temporary hybrid OpenStack environment that is only used to upgrade the Compute nodes one by one by re-assigning them to the 7.0 environment and re-installing with the new version.
- Ceph OSD nodes from the 6.1 environment transparently switch to the new Monitors without the actual data moving in the Ceph cluster.
- User data stored on OSD nodes must be preserved through re-installation of the nodes into a new release of the operating system and OpenStack services, and OSD nodes must connect to the Monitors without changing their original IDs and data set.
Every step requires certain actions. All of these actions are scripted as subcommands to the upgrade script called 'octane'.
Prerequisites and dependencies
The procedure of upgrading Mirantis OpenStack from 6.1 to 7.0 version has certain prerequisites and dependencies. You need to verify if your installation of Mirantis OpenStack meets these requirements.
Fuel installer
Mirantis OpenStack 6.1 environment must be deployed and managed by
Fuel installer to be upgradeable. If you installed your environment
without leveraging Fuel, or removed the Fuel Master node <fuel-master-node-term> from
the installation after a successful deployment, you will not be able to
upgrade your environments using these instructions.
The upgrade scenario deviates from the standard sequence used in Fuel
installer to deploy Mirantis OpenStack environment. These modifications
to the behavior of the installer are implemented as modifications to the
deployment tasks <0010-tasks-schema> and
extensions to certain components of Fuel. Patches are applied to the
Fuel Master node as part of 'preparation' phase of the Upgrade scenario.
See the sections below for the detailed description of which components
are modified and why.
Architecture constraints
Make sure that your Mirantis OpenStack 6.1 environment meets the following architecture constraints. Otherwise, these instructions will not work for you:
| Constraint | Check if comply |
|---|---|
| High Availability architecture | |
| Ubuntu 14.04 as an operating system | |
| Neutron networking manager with OVS+VLAN plugin | |
| Cinder virtual block storage volumes | |
| Ceph shared storage for volumes and ephemeral data | |
| Ceph shared storage for images and objeсt store |
Fuel upgrade to 7.0
In this guide we assume that the user upgrades Fuel installer from version 6.1 to 7.0. The upgrade of Fuel installer is a standard feature of the system. Upgraded Fuel retains the ability to manage 6.1 environments, which is leveraged by the environment upgrade solution.
Additional hardware
The upgrade strategy requires installing 7.0 environment that will result in an OpenStack cluster along with the original environment. One of the Controller nodes from the original 6.1 environment will be deleted, added to the new 7.0 environment, and reinstalled. This allows performing an upgrade with no additional hardware.
Note
The trade-off for using one of the existing controllers as a primary upgraded controller is that the 7.0 environment will not be highly available for some time during the maintenance window dedicated to the upgrade. Once the remaining controllers are moved from the 6.1 environment and reinstalled into the 7.0 environment, its High Availability is restored.