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Copyright (c) 2016 IBM
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Licensed under the Apache License, Version 2.0 (the "License"); you may
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not use this file except in compliance with the License. You may obtain
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a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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License for the specific language governing permissions and limitations
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under the License.
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===================
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Introducing Octavia
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===================
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Welcome to Octavia!
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Octavia is an open source, operator-scale load balancing solution designed to
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work with OpenStack.
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Octavia was borne out of the Neutron LBaaS project. Its conception influenced
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the transformation of the Neutron LBaaS project, as Neutron LBaaS moved from
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version 1 to version 2. Starting with the Liberty release of OpenStack, Octavia
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has become the reference implementation for Neutron LBaaS version 2.
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Octavia accomplishes its delivery of load balancing services by managing a
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fleet of virtual machines, containers, or bare metal servers—collectively known
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as *amphorae*\— which it spins up on demand. This on-demand, horizontal scaling
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feature differentiates Octavia from other load balancing solutions, thereby
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making Octavia truly suited "for the cloud."
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Where Octavia fits into the OpenStack ecosystem
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-----------------------------------------------
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Load balancing is essential for enabling simple or automatic delivery scaling
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and availability. In turn, application delivery scaling and availability must
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be considered vital features of any cloud. Together, these facts imply that
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load balancing is a vital feature of any cloud.
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Therefore, we consider Octavia to be as essential as Nova, Neutron, Glance or
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any other "core" project that enables the essential features of a modern
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OpenStack cloud.
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In accomplishing its role, Octavia makes use of other OpenStack projects:
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* **Nova** - For managing amphora lifecycle and spinning up compute resources
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on demand.
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* **Neutron** - For network connectivity between amphorae, tenant environments,
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and external networks.
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* **Barbican** - For managing TLS certificates and credentials, when TLS
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session termination is configured on the amphorae.
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* **Keystone** - For authentication against the Octavia API, and for Octavia to
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authenticate with other OpenStack projects.
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* **Glance** - For storing the amphora virtual machine image.
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* **Oslo** - For communication between Octavia controller components, making
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Octavia work within the standard OpenStack framework and review system, and
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project code structure.
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* **Taskflow** - Is technically part of Oslo; however, Octavia makes
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extensive use of this job flow system when orchestrating back-end service
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configuration and management.
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Octavia is designed to interact with the components listed previously. In each
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case, we’ve taken care to define this interaction through a driver interface.
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That way, external components can be swapped out with functionally-equivalent
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replacements— without having to restructure major components of Octavia. For
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example, if you use an SDN solution other than Neutron in your environment, it
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should be possible for you to write an Octavia networking driver for your SDN
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environment, which can be a drop-in replacement for the standard Neutron
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networking driver in Octavia.
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It is important for you to know that Octavia is not necessarily designed as a
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complete replacement for the Neutron LBaaS project. That is to say, Octavia is
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designed to "plug in" to Neutron LBaaS in the same way that any proprietary
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vendor solution would: through a Neutron LBaaS version 2 driver interface. You
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could think of Octavia as an "open source vendor" for Neutron LBaaS, rather
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than as a substitute for Neutron LBaaS. For this reason, we recommend that
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tenants configure load balancing services with Octavia through the Neutron
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LBaaS version 2 CLI and API.
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Soon, Octavia will supplant Neutron LBaaS as the load balancing solution for
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OpenStack. At that time, third-party vendor drivers that presently "plug in"
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to Neutron LBaaS will plug in to Octavia instead. For end-users, this
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transition should be relatively seamless, because Octavia supports the Neutron
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LBaaS v2 API and it has a similar CLI interface.
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Octavia terminology
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-------------------
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Before you proceed further in this introduction, please note:
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Experience shows that—within the subsegment of the IT industry that creates,
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deploys, and uses load balancing devices or services— terminology is often used
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inconsistently. To reduce confusion, the Octavia team has created a glossary of
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terms as they are defined and used within the context of the Octavia project
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and Neutron LBaaS version 2. This glossary is available here: :doc:`glossary`
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If you are familiar with Neutron LBaaS version 1 terms and usage, it is
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especially important for you to understand how the meanings of the terms “VIP,"
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"load balancer," and "load balancing," have changed in Neutron LBaaS version 2.
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Our use of these terms should remain consistent with the :doc:`glossary`
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throughout Octavia's documentation, in discussions held by Octavia team members
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on public mailing lists, in IRC channels, and at conferences. To avoid
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misunderstandings, it's a good idea to familiarize yourself with these glossary
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definitions.
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A 10,000-foot overview of Octavia components
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--------------------------------------------
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.. image:: octavia-component-overview.svg
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:width: 660px
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:alt: Octavia Component Overview
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Octavia version 0.9 consists of the following major components:
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* **amphorae** - Amphorae are the individual virtual machines, containers, or
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bare metal servers that accomplish the delivery of load balancing services to
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tenant application environments. In Octavia version 0.8, the reference
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implementation of the amphorae image is an Ubuntu virtual machine running
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HAProxy.
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* **controller** - The Controller is the "brains" of Octavia. It consists of
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four sub-components, which are individual daemons. They can be run on
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separate back-end infrastructure if desired:
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* **API Controller** - As the name implies, this subcomponent runs Octavia's
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API. It takes API requests, performs simple sanitizing on them, and ships
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them off to the controller worker over the Oslo messaging bus.
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* **Controller Worker** - This subcomponent takes sanitized API commands from
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the API controller and performs the actions necessary to fulfill the API
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request.
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* **Health Manager** - This subcomponent monitors individual amphorae to
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ensure they are up and running, and otherwise healthy. It also handles
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failover events if amphorae fail unexpectedly.
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* **Housekeeping Manager** - This subcomponent cleans up stale (deleted)
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database records, manages the spares pool, and manages amphora certificate
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rotation.
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* **network** - Octavia cannot accomplish what it does without manipulating
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the network environment. Amphorae are spun up with a network interface on the
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"load balancer network," and they may also plug directly into tenant networks
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to reach back-end pool members, depending on how any given load balancing
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service is deployed by the tenant.
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For a more complete description of Octavia's components, please see the
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:doc:`../design/version0.5/component-design` document within this documentation
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repository.
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