145 lines
6.1 KiB
ReStructuredText
145 lines
6.1 KiB
ReStructuredText
===========================
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Bare Metal service overview
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===========================
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The Bare Metal service, codenamed ``ironic``, is a collection of components
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that provides support to manage and provision physical machines.
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Bare Metal service components
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-----------------------------
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The Bare Metal service includes the following components:
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ironic-api
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A RESTful API that processes application requests by sending them to the
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ironic-conductor over `remote procedure call (RPC)`_. Can be run through
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WSGI_ or as a separate process.
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ironic-conductor
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Adds/edits/deletes nodes; powers on/off nodes with IPMI or other
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vendor-specific protocol; provisions/deploys/cleans bare metal nodes.
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ironic-conductor uses :doc:`drivers </install/enabling-drivers>` to execute
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operations on hardware.
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ironic-python-agent
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A python service which is run in a temporary ramdisk to provide
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ironic-conductor and ironic-inspector services with remote access, in-band
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hardware control, and hardware introspection.
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Additionally, the Bare Metal service has certain external dependencies, which
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are very similar to other OpenStack services:
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- A database to store hardware information and state. You can set the database
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back-end type and location. A simple approach is to use the same database
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back end as the Compute service. Another approach is to use a separate
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database back-end to further isolate bare metal resources (and associated
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metadata) from users.
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- An :oslo.messaging-doc:`oslo.messaging <>`
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compatible queue, such as RabbitMQ. It may use the same
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implementation as that of the Compute service, but that is not a requirement.
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Used to implement RPC between ironic-api and ironic-conductor.
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Deployment architecture
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-----------------------
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The Bare Metal RESTful API service is used to enroll hardware that the Bare
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Metal service will manage. A cloud administrator usually registers it,
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specifying their attributes such as MAC addresses and IPMI credentials.
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There can be multiple instances of the API service.
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The *ironic-conductor* process does the bulk of the work. For security
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reasons, it is advisable to place it on an isolated host, since it is the only
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service that requires access to both the data plane and IPMI control plane.
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There can be multiple instances of the conductor service to support
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various class of drivers and also to manage fail over. Instances of the
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conductor service should be on separate nodes. Each conductor can itself run
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many drivers to operate heterogeneous hardware. This is depicted in the
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following figure.
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.. figure:: ../images/deployment_architecture_2.png
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:alt: Deployment Architecture
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The API exposes a list of supported drivers and the names of conductor hosts
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servicing them.
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Interaction with OpenStack components
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-------------------------------------
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The Bare Metal service may, depending upon configuration, interact with several
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other OpenStack services. This includes:
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- the OpenStack Telemetry module (``ceilometer``) for consuming the IPMI
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metrics
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- the OpenStack Identity service (``keystone``) for request authentication and
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to locate other OpenStack services
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- the OpenStack Image service (``glance``) from which to retrieve images and
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image meta-data
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- the OpenStack Networking service (``neutron``) for DHCP and network
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configuration
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- the OpenStack Compute service (``nova``) works with the Bare Metal service
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and acts as a user-facing API for instance management, while the Bare Metal
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service provides the admin/operator API for hardware management. The
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OpenStack Compute service also provides scheduling facilities (matching
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flavors <-> images <-> hardware), tenant quotas, IP assignment, and other
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services which the Bare Metal service does not, in and of itself, provide.
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- the OpenStack Object Storage (``swift``) provides temporary storage
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for the configdrive, user images, deployment logs and inspection data.
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Logical architecture
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--------------------
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The diagram below shows the logical architecture. It shows the basic
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components that form the Bare Metal service, the relation of the Bare Metal
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service with other OpenStack services and the logical flow of a boot instance
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request resulting in the provisioning of a physical server.
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.. figure:: ../images/logical_architecture.png
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:alt: Logical Architecture
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A user's request to boot an instance is passed to the Compute service via
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the Compute API and the Compute Scheduler. The Compute service uses the
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*ironic virt driver* to hand over this request to the Bare Metal service,
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where the request passes from the Bare Metal API, to the Conductor, to a Driver
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to successfully provision a physical server for the user.
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Just as the Compute service talks to various OpenStack services like
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Image, Network, Object Store etc to provision a virtual machine instance, here
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the Bare Metal service talks to the same OpenStack services for image, network
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and other resource needs to provision a bare metal instance.
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See :ref:`understanding-deployment` for a more detailed breakdown of
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a typical deployment process.
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Associated projects
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-------------------
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Optionally, one may wish to utilize the following associated projects for
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additional functionality:
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:python-ironicclient-doc:`python-ironicclient <>`
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A command-line interface (CLI) and python bindings for interacting with the
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Bare Metal service.
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:ironic-ui-doc:`ironic-ui <>`
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Horizon dashboard, providing graphical interface (GUI) for the Bare Metal
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API.
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:ironic-inspector-doc:`ironic-inspector <>`
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An associated service which performs in-band hardware introspection by
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PXE booting unregistered hardware into the ironic-python-agent ramdisk.
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diskimage-builder_
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A related project to help facilitate the creation of ramdisks and machine
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images, such as those running the ironic-python-agent.
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:bifrost-doc:`bifrost <>`
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A set of Ansible playbooks that automates the task of deploying a base image
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onto a set of known hardware using ironic in a standalone mode.
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.. _remote procedure call (RPC): https://en.wikipedia.org/wiki/Remote_procedure_call
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.. _WSGI: https://en.wikipedia.org/wiki/Web_Server_Gateway_Interface
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.. _diskimage-builder: https://docs.openstack.org/diskimage-builder/latest/
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