330 lines
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330 lines
13 KiB
ReStructuredText
===============================
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Welcome to Ironic Python Agent!
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===============================
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Overview
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========
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Ironic Python Agent is an agent for controlling and deploying Ironic controlled
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baremetal nodes. Typically run in a ramdisk, the agent exposes a REST API for
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provisioning servers.
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Throughout the documentation, Ironic Python Agent will be
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abbreviated to IPA.
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Index
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=====
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.. toctree::
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contributor/index
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troubleshooting
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How it works
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============
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Integration with Ironic
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-----------------------
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Compatible Deploy Drivers
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~~~~~~~~~~~~~~~~~~~~~~~~~
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Agent Deploy Driver
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<<<<<<<<<<<<<<<<<<<
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IPA works with the agent Deploy driver in Ironic to provision nodes. Starting
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with ironic-python-agent running on a ramdisk on an unprovisioned node,
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Ironic makes API calls to ironic-python-agent to provision the machine. This
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allows for greater control and flexibility of the entire deployment process.
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PXE Deploy Driver
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<<<<<<<<<<<<<<<<<
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IPA may also be used with the original Ironic pxe driver as of the Kilo
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OpenStack Ironic release.
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Configuring Deploy Drivers
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<<<<<<<<<<<<<<<<<<<<<<<<<<
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For information on how to install and configure Ironic drivers, including
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drivers for IPA, see the Ironic drivers documentation [0]_.
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Lookup
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~~~~~~
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On startup, the agent performs a lookup in Ironic to determine its node UUID
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by sending a hardware profile to the Ironic lookup endpoint:
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``/v1/lookup``.
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Heartbeat
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~~~~~~~~~
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After successfully looking up its node, the agent heartbeats via
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``/v1/heartbeat/{node_ident}`` every N seconds, where
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N is the Ironic conductor's agent.heartbeat_timeout value multiplied by a
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number between .3 and .6.
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For example, if your conductor's ironic.conf contains::
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[agent]
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heartbeat_timeout = 60
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IPA will heartbeat between every 20 and 36 seconds. This is to ensure jitter
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for any agents reconnecting after a network or API disruption.
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After the agent heartbeats, the conductor performs any actions needed against
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the node, including querying status of an already run command. For example,
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initiating in-band cleaning tasks or deploying an image to the node.
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Inspection
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~~~~~~~~~~
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IPA can conduct hardware inspection on start up and post data to the `Ironic
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Inspector`_. Edit your default PXE/iPXE configuration or IPA options
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baked in the image, and set ``ipa-inspection-callback-url`` to the
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full endpoint of Ironic Inspector, for example::
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ipa-inspection-callback-url=http://IP:5050/v1/continue
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Make sure your DHCP environment is set to boot IPA by default.
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.. _Ironic Inspector: http://docs.openstack.org/developer/ironic-inspector/
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Hardware Inventory
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------------------
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IPA collects various hardware information using its `Hardware Managers`_,
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and sends it to Ironic on lookup and to Ironic Inspector on Inspection_.
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The exact format of the inventory depends on the hardware manager used.
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Here is the basic format expected to be provided by all hardware managers.
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The inventory is a dictionary (JSON object), containing at least the following
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fields:
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``cpu``
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CPU information: ``model_name``, ``frequency``, ``count``,
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``architecture`` and ``flags``.
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``memory``
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RAM information: ``total`` (total size in bytes), ``physical_mb``
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(physically installed memory size in MiB, optional).
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.. note::
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The difference is that the latter includes the memory region reserved
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by the kernel and is always slightly bigger. It also matches what
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the Nova flavor would contain for this node and thus is used by the
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inspection process instead of ``total``.
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``bmc_address``
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IP address of the node's BMC (aka IPMI address), optional.
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``disks``
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list of disk block devices with fields: ``name``, ``model``,
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``size`` (in bytes), ``rotational`` (boolean), ``wwn``, ``serial``,
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``vendor``, ``wwn_with_extension``, ``wwn_vendor_extension``, ``hctl``.
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``interfaces``
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list of network interfaces with fields: ``name``, ``mac_address``,
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``ipv4_address``, ``lldp``, ``vendor``, ``product``, and optionally
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``biosdevname``(BIOS given NIC name). If configuration option
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``collect_lldp`` is set to True the ``lldp`` field will be populated
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by a list of type-length-value(TLV) fields retrieved using the
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Link Layer Discovery Protocol (LLDP).
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``system_vendor``
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system vendor information from SMBIOS as reported by ``dmidecode``:
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``product_name``, ``serial_number`` and ``manufacturer``.
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``boot``
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boot information with fields: ``current_boot_mode`` (boot mode used for
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the current boot - BIOS or UEFI) and ``pxe_interface`` (interface used
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for PXE booting, if any).
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Image Builders
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--------------
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Unlike most other python software, you must build an IPA ramdisk image before
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use. This is because it's not installed in an operating system, but instead is
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run from within a ramdisk.
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CoreOS
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~~~~~~
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One way to build a ramdisk image for IPA is with the CoreOS image [1]_.
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Prebuilt copies of the CoreOS image, suitable for pxe, are available on
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`tarballs.openstack.org <http://tarballs.openstack.org/ironic-python-agent/coreos/files/>`__.
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Build process
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<<<<<<<<<<<<<
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On a high level, the build steps are as follows:
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1) A docker build is performed using the ``Dockerfile`` in the root of the
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ironic-python-agent project.
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2) The resulting docker image is exported to a filesystem image.
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3) The filesystem image, along with a cloud-config.yml [2]_, are embedded into
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the CoreOS PXE image at /usr/share/oem/.
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4) On boot, the ironic-python-agent filesystem image is extracted and run
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inside a systemd-nspawn container. /usr/share/oem is mounted into this
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container as /mnt.
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Customizing the image
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<<<<<<<<<<<<<<<<<<<<<
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There are several methods you can use to customize the IPA ramdisk:
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* Embed SSH keys by putting an authorized_keys file in /usr/share/oem/
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* Add your own hardware managers by modifying the Dockerfile to install
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additional python packages.
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* Modify the cloud-config.yml [2]_ to perform additional tasks at boot time.
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diskimage-builder
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~~~~~~~~~~~~~~~~~~
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Another way to build a ramdisk image for IPA is by using diskimage-builder
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[3]_. The ironic-agent diskimage-builder element builds the IPA ramdisk, which
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installs all the required packages and configures services as needed.
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tinyipa
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~~~~~~~
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Ironic Python Agent repo also provides a set of scripts to build a
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Tiny Core Linux-based deployment kernel and ramdisk (code name ``tinyipa``)
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under ``imagebuild/tinyipa`` folder.
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`Tiny Core Linux <http://tinycorelinux.net/>`_
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is a very minimalistic Linux distribution.
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Due to its small size and decreased RAM requirements
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it is mostly suitable for usage in CI with virtualized hardware,
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and is already used on a number of gate jobs in projects under
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OpenStack Baremetal program.
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On the other hand, due to its generally newer Linux kernel it also known to
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work on real hardware if the kernel supports all necessary components
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installed.
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Please refer to ``imagebuild/tinyipa/README.rst`` for more information and
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build instructions.
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ISO Images
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~~~~~~~~~~
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Additionally, the IPA ramdisk can be packaged inside of an ISO for use with
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supported virtual media drivers. Simply use the ``iso-image-create`` utility
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packaged with IPA, pass it an initrd and kernel. e.g.::
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./iso-image-create -o /path/to/output.iso -i /path/to/ipa.initrd -k /path/to/ipa.kernel
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This is a generic tool that can be used to combine any initrd and kernel into
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a suitable ISO for booting, and so should work against any IPA ramdisk created
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-- both DIB and CoreOS.
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IPA Flags
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=========
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You can pass a variety of flags to IPA on start up to change its behavior.
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If you're using the CoreOS image, you can modify the
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ironic-python-agent.service unit in cloud-config.yaml [5]_.
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* ``--standalone``: This disables the initial lookup and heartbeats to Ironic.
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Lookup sends some information to Ironic in order to determine Ironic's node
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UUID for the node. Heartbeat sends periodic pings to Ironic to tell Ironic
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the node is still running. These heartbeats also trigger parts of the deploy
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and cleaning cycles. This flag is useful for debugging IPA without an Ironic
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installation.
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* ``--debug``: Enables debug logging.
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IPA and SSL
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===========
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During its operation IPA makes HTTP requests to a number of other services,
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currently including
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- ironic for lookup/heartbeats
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- ironic-inspector to publish results of introspection
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- HTTP image storage to fetch the user image to be written to the node's disk
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(Object storage service or other service storing user images
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when ironic is running in a standalone mode)
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When these services are configured to require SSL-encrypted connections,
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IPA can be configured to either properly use such secure connections or
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ignore verifying such SSL connections.
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Configuration mostly happens in the IPA config file
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(default is ``/etc/ironic_python_agent/ironic_python_agent.conf``)
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or command line arguments passed to ``ironic-python-agent``,
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and it is possible to provide some options via kernel command line arguments
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instead.
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Available options in the ``[DEFAULT]`` config file section are:
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insecure
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Whether to verify server SSL certificates.
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When not specified explicitly, defaults to the value of ``ipa-insecure``
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kernel command line argument (converted to boolean).
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The default for this kernel command line argument is taken to be ``False``.
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Overriding it to ``True`` by adding ``ipa-insecure=1`` to the value of
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``[pxe]pxe_append_params`` in ironic configuration file will allow running
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the same IPA-based deploy ramdisk in a CI-like environment when services
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are using secure HTTPS endpoints with self-signed certificates without
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adding a custom CA file to the deploy ramdisk (see below).
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cafile
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Path to the PEM encoded Certificate Authority file.
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When not specified, available system-wide list of CAs will be used to
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verify server certificates.
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Thus in order to use IPA with HTTPS endpoints of other services in
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a secure fashion (with ``insecure`` option being ``False``, see above),
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operators should either ensure that certificates of those services
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are verifiable by root CAs present in the deploy ramdisk,
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or add a custom CA file to the ramdisk and set this IPA option to point
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to this file at ramdisk build time.
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certfile
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Path to PEM encoded client certificate cert file.
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This option must be used when services are configured to require client
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certificates on SSL-secured connections.
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This cert file must be added to the deploy ramdisk and path
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to it specified for IPA via this option at ramdisk build time.
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This option has an effect only when the ``keyfile`` option is also set.
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keyfile
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Path to PEM encoded client certificate key file.
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This option must be used when services are configured to require client
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certificates on SSL-secured connections.
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This key file must be added to the deploy ramdisk and path
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to it specified for IPA via this option at ramdisk build time.
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This option has an effect only when the ``certfile`` option is also set.
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Currently a single set of cafile/certfile/keyfile options is used for all
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HTTP requests to the other services.
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Securing IPA's HTTP server itself with SSL is not yet supported in default
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ramdisk builds.
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Hardware Managers
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=================
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What is a HardwareManager?
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--------------------------
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Hardware managers are how IPA supports multiple different hardware platforms
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in the same agent. Any action performed on hardware can be overridden by
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deploying your own hardware manager.
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Why build a custom HardwareManager?
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-----------------------------------
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Custom hardware managers allow you to include hardware-specific tools, files
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and cleaning steps in the Ironic Python Agent. For example, you could include a
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BIOS flashing utility and BIOS file in a custom ramdisk. Your custom
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hardware manager could expose a cleaning step that calls the flashing utility
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and flashes the packaged BIOS version (or even download it from a tested web
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server).
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How can I build a custom HardwareManager?
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-----------------------------------------
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Operators wishing to build their own hardware managers should reference
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the documentation available at [4]_.
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References
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==========
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.. [0] Enabling Drivers - http://docs.openstack.org/developer/ironic/drivers/ipa.html
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.. [1] CoreOS PXE Images - https://coreos.com/docs/running-coreos/bare-metal/booting-with-pxe/
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.. [2] CoreOS Cloud Init - https://coreos.com/docs/cluster-management/setup/cloudinit-cloud-config/
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.. [3] DIB Element for IPA - http://docs.openstack.org/developer/diskimage-builder/elements/ironic-agent/README.html
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.. [4] Hardware Managers - https://docs.openstack.org/ironic/latest/contributor/hardware_managers.html
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.. [5] cloud-config.yaml - https://git.openstack.org/cgit/openstack/ironic-python-agent/tree/imagebuild/coreos/oem/cloud-config.yml
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Indices and tables
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==================
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* :ref:`genindex`
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* :ref:`search`
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