Merge "Nova compatible serial console support"
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specs/approved/nova-compatible-serial-console.rst
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specs/approved/nova-compatible-serial-console.rst
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..
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This work is licensed under a Creative Commons Attribution 3.0 Unported
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License.
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http://creativecommons.org/licenses/by/3.0/legalcode
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==============================
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Nova-compatible Serial Console
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==============================
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https://bugs.launchpad.net/ironic/+bug/1553083
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This implements console interfaces using "socat" which provides nova-
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compatible serial console capability.
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Problem description
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===================
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Currently, ironic's only console interface is based on shellinabox,
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which provides a stand-alone web console, and is not compatible with
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nova-serialproxy.
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Proposed change
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===============
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In order to address the problem of not having a serial console compatible with
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nova, this spec proposes using a command line tool ``socat`` [#]_ in
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conjunction with IPMI Serial-Over-Lan capabilities.
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``socat`` is a command line based utility that establishes two bidirectional
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byte streams and transfers data between them.
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This application allows us to activate the ipmitool Serial-over-LAN
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process and redirect it through a TCP connection which can then be consumed
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by the ``nova-serialproxy`` service.
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Each console (socat + ipmitool) will run on its own process on the same host
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that the ironic-conductor which is currently managing that node is running.
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``socat`` will run first, then it will execute ipmitool when it has connections
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from ``nova-serialproxy``, and will work like a ``bridge`` between them.
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Start/stop of an ironic-conductor process
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-----------------------------------------
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* When ironic-conductor starts, if console mode of the node is true, start
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socat also.
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* When ironic-conductor stops, if console is started, stop it.
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* About takeover work, we're planning:
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* When an ironic-conductor stops, console session will be stopped due to
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security reason. In this case, if there are other ironic-conductors,
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they takeover nodes and enables their console session again.
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* When ironic-conductor starts, if there are console enabled nodes, the
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ironic-conductor starts their console.
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* Start/stop console will be implemented with subprocess.Popen.
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* About start/stop socat, we're planning to implement a new console interface
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IPMISocatConsole and implement same methods as shellinabox classes.
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About this, discussed in: [#]_ .
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* About reconnection, for example, in case of temporary network problem with
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using Horizon, "Closed" message will be shown. And socat itself
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supports session reconnect from client side, so that, when the network
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problem is resolved, users can try to reconnect.
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Specify which of shellinabox or socat to use
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--------------------------------------------
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We're planning to specify which driver to use shellinabox or socat by setting
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driver like ``pxe_ipmitool_socat`` or ``agent_ipmitool_socat``.
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(Please see ``Other deployer impact`` section.)
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Alternatives
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------------
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Creating a new service "ironic-xxx" instead of adding a new ConsoleInterface
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to ``ironic-conductor`` . The upside of new service is that it can be scaled
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independently, and has no implications on conductor failover. However
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it will need its own HA model as well, and will be more work for developers
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(API, DB, driver, ...).
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Data model impact
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-----------------
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None
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State Machine Impact
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--------------------
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None
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REST API impact
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---------------
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The response body of "GET /v1/nodes/<UUID>/states/console" contains a
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JSON object like below::
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{
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"console_enabled": true,
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"console_info": {
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"url": <url>,
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"type": <type>
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}
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}
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In case of using socat instead of shellinabox,
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<type> will be "socat" and <url> is like "tcp://<host>:<port>".
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Client (CLI) impact
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-------------------
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None
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RPC API impact
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--------------
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None
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Driver API impact
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-----------------
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None
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Nova driver impact
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------------------
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get_serial_console() will be implemented in ironic driver of Nova. It
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returns a dictionary, similar to
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nova.virt.libvirt.driver.LibvirtDriver.get_serial_console(). No other
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impact for nova, and nova-serialproxy works well with the new one.
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And also, nova has agreed to the nova side of the work [#]_.
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Security impact
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---------------
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The connection between nova-serialproxy and socat is TCP based, like
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KVM. Socat supports OpenSSL connections, so we can improve the
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security in the future.
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Other end user impact
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---------------------
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None
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Scalability impact
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------------------
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If a conductor can service 1000 nodes, and a process is created for a console
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to each node, but it's the same scalability issue as shellinabox.
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Performance Impact
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------------------
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None
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Other deployer impact
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---------------------
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To use socat serial console, deployer needs to specify new driver.
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For example, to use PXE + IPMItool + socat, specify ``pxe_ipmitool_socat``.
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To use IPA + IPMItool + socat, specify ``agent_ipmitool_socat``.
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To use existing shellinabox console, deployer doesn't need to change anything.
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We will implement new driver ``IPMISocatConsole`` initially, so that just
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``pxe_ipmitool_socat`` and ``agent_ipmitool_socat`` drivers will support socat
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console. After ``Driver composition reform`` [#]_ is implemented, this feature
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will be available for a lot more drivers (or hardware types).
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About configuration options, existing options ``terminal``,
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``terminal_pid_dir``, ``subprocess_checking_interval``, ``subprocess_timeout``
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are available for socat in the same way as shellinabox.
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``terminal_cert_dir`` is not used in the case of socat because SSL is not
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supported.
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To use socat, .conf file will be::
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[console]
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# Path to serial console terminal program. "shellinaboxd"
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# provides stand-alone web console. "socat" provides
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# Nova-compatible serial console. Notes that only
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# a few drivers support "socat". (string value)
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terminal = shellinaboxd
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# Directory containing the terminal SSL cert(PEM) for serial
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# console access. Notes that only Shellinabox console uses
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# this value. (string value)
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terminal_cert_dir = <None>
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# Directory for holding terminal pid files. If not specified,
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# the temporary directory will be used. (string value)
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terminal_pid_dir = <None>
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# Time interval (in seconds) for checking the status of
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# console subprocess. (integer value)
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subprocess_checking_interval = 1
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# Time (in seconds) to wait for the console subprocess to
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# start. (integer value)
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subprocess_timeout = 10
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Developer impact
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----------------
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None
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Implementation
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==============
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Assignee(s)
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-----------
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Primary assignee:
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* Akira Yoshiyama <akirayoshiyama@gmail.com>
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Other contributors:
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* Dao Cong Tien <tiendc@vn.fujitsu.com>
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* Nguyen Tuong Thanh <thanhnt@vn.fujitsu.com>
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* Cao Xuan Hoang<hoangcx@vn.fujitsu.com >
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* Hironori Shiina <shiina.hironori@jp.fujitsu.com>
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* Yuiko Takada Mori <y-mori@ti.jp.nec.com>
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Work Items
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----------
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* Implement ``IPMISocatConsole`` and ``NativeIPMISocatConsole`` class
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inherited from ``base.ConsoleInterface``.
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Dependencies
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============
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None
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Testing
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=======
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Unit Testing will be added.
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Upgrades and Backwards Compatibility
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====================================
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None
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Documentation Impact
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====================
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Add configuration description to the install guide.
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References
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==========
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.. [#] http://linux.die.net/man/1/socat
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.. [#] https://review.openstack.org/#/c/293873/
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.. [#] https://blueprints.launchpad.net/nova/+spec/ironic-serial-console-support
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.. [#] https://review.openstack.org/#/c/188370/
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1
specs/not-implemented/nova-compatible-serial-console.rst
Symbolic link
1
specs/not-implemented/nova-compatible-serial-console.rst
Symbolic link
@ -0,0 +1 @@
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../approved/nova-compatible-serial-console.rst
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