.. This work is licensed under a Creative Commons Attribution 3.0 Unported License. http://creativecommons.org/licenses/by/3.0/legalcode ===================== Discover ironic nodes ===================== https://bugs.launchpad.net/ironic-inspector/+bug/1524753 This spec proposes auto-discovery of Ironic nodes feature. Problem description =================== A large network might consist of hundreds of servers. Keeping track of these servers can be a time-consuming process. Auto-discovery could simplify the addition of new servers into Ironic. It will identifies a resource automatically so it's possible to manage it. For now, Ironic is unable to automatically detect nodes. Operators have to create nodes manually and provide driver info for them. Proposed change =============== Nodes that don't exist in the inspector node cache may still be booted and return inspection information to process, the ``node-not-found-hook`` hook is run by the inspector when it receives information from a node it can not identify. For auto-discovery a new hook that will plugin at this point will be written, called ``enroll``. The hook will enroll the unknown node into Ironic with the ``fake`` driver (this driver is a configurable option, set ``enroll_node_driver`` in the configuration file allows to change the Ironic driver). Also the ``enroll`` hook will set the ``ipmi_address`` property on the new node, if its available in the introspection data we received. To customize discovery, introspection rules will be used, it allows operators to control the discovery process. A simple rule to match all new nodes and enroll them in Ironic with the ``agent_ipmitool`` driver will looks like:: "description": "Set IPMI driver_info if no address or credentials", "actions": [ {'action': 'set-attribute', 'path': 'driver', 'value': 'agent_ipmitool'}, {'action': 'set-attribute', 'path': 'driver_info/ipmi_address', 'value': '{data[ipmi_address]}'}, {'action': 'set-attribute', 'path': 'driver_info/ipmi_username', 'value': 'username'}, {'action': 'set-attribute', 'path': 'driver_info/ipmi_password', 'value': 'password'} ] "conditions": [ {'op': 'eq', 'field': 'node://driver_info/ipmi_password', 'multiple': 'all', 'value': None}, {'op': 'eq', 'field': 'node://driver_info/ipmi_username', 'multiple': 'all', 'value': None} ] "description": "Set deploy info if not already set on node", "actions": [ {'action': 'set-attribute', 'path': 'driver_info/deploy_kernel', 'value': ''}, {'action': 'set-attribute', 'path': 'driver_info/deploy_ramdisk', 'value': ''}, ] "conditions": [ {'op': 'eq', 'field': 'node://driver_info.deploy_ramdisk', 'multiple': 'all', 'value': None}, {'op': 'eq', 'field': 'node://driver_info.deploy_kernel', 'multiple': 'all', 'value': None} ] Rule changes: - condition changes: extend field ``field``, for now it's represent a `JSON path`_ to the field in the introspection data to use in comparison. But sometimes it's needed to compare data from node(``deploy_ramdisk`` compared with None in example), so to get data from node, ``node://`` and ``data://`` scheme proposed to add. It will allow to fetch data using path from the nodes info and introspection(``data://`` is default scheme to keep backward compatibility):: node://driver_info.deploy_ramdisk - ``deploy_ramdisk`` attribute from node's driver_info. data://memory_mb - ``memory_mb`` attribute from introspection data. - actions changes: for now it's impossible to assign values from inspection data to node, to address this disadvantage it's proposed to add standard python formatting `Python format`_ to ``value`` field. For example, ``set-attribute`` sets an attribute on an Ironic node. It's required the ``path`` field, which is the path to the attribute in Ironic, e.g.``driver_info/ipmi_username``, and a ``value`` to set. Where ``value`` is simple value, which assigned to path:: {data[ipmi_address]} - ``ipmi_address`` attribute from introspection data will be fetched. All nodes discovered and enrolled via the ``enroll`` hook, will contain an ``auto_discovered`` flag in the introspection data, this flag makes it possible to distinguish between manually enrolled nodes and auto-discovered nodes in the introspection rules using the rule condition ``eq``:: "description": "Enroll auto-discovered nodes with fake driver", "actions": [ {'action': 'set-attribute', 'path': 'driver', 'value': 'fake'} ] "conditions": [ {'op': 'eq', 'field': 'data://auto_discovered', 'value': True} ] Creating new actions will allow the node info to be consumed in different ways. Proposed approach is pretty flexible, so more sophisticated conditions and actions could be added here based on operators specifications. Operator steps for achieve auto-discovery would be following: * Operator creates a new rule or uses the predefined ``discovery rule``; * Operator import rule to Inspector; * All nodes after rule is imported will be discovered with it. Alternatives ------------ Continue enroll nodes manually and run inspection. But it's not appropriate approach for big significant environments. API impact ---------- None Performance and scalability impact ---------------------------------- None Security impact --------------- None Deployer impact --------------- Note: before discovery, the config option ``node_not_found_hook`` should be assigned to the ``enroll_node_not_found_hook`` value; deployers will be required to create rules, so they should be familiar with rules, rules conditions and actions; for simple cases example rules could be used. Developer impact ---------------- Developers can create additional conditions and actions regarding their needs to extend the discovery process. Implementation ============== Assignee(s) ----------- * Anton Arefiev(aarefiev) Work Items ---------- * Extend conditions and actions to support proposed format; * Cover new functionality with unit and integration tests; * Add example rules; * Update docs. Dependencies ============ None Testing ======= Unit, functional and integration tests will be added. References ========== .. _`JSON path`: http://goessner.net/articles/JsonPath/ .. _`Python format`: https://docs.python.org/3/library/stdtypes.html#str.format