78dfa05258
* Improve comments in tenks_update_state * Add limitations section to README * Add hosts blurb to README * Add reconfiguration blurb to README
312 lines
12 KiB
Python
312 lines
12 KiB
Python
# Copyright (c) 2018 StackHPC Ltd.
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#
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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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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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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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# Avoid shadowing of system copy module by copy action plugin.
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from __future__ import absolute_import
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import abc
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from copy import deepcopy
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import itertools
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import re
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from ansible.errors import AnsibleActionFail
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from ansible.module_utils._text import to_text
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from ansible.plugins.action import ActionBase
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import six
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class ActionModule(ActionBase):
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def run(self, tmp=None, task_vars=None):
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"""
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Produce a dict of Tenks state.
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Actions include:
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* Generating indices for physical networks for each hypervisor.
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* Scheduling specifications of nodes by type onto hypervisors.
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The following task vars are accepted:
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:hypervisor_vars: A dict of hostvars for each hypervisor, keyed
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by hypervisor hostname. Required.
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:specs: A list of node specifications to be instantiated. Required.
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:node_types: A dict mapping node type names to a dict of properties
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of that type.
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:node_name_prefix: A string with which to prefix all sequential
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node names.
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:vol_name_prefix: A string with which to prefix all sequential
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volume names.
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:state: A dict of existing Tenks state (as produced by a previous
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run of this module), to be taken into account in this run.
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Optional.
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:returns: A dict of Tenks state for each hypervisor, keyed by the
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hostname of the hypervisor to which the state refers.
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"""
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result = super(ActionModule, self).run(tmp, task_vars)
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# Initialise our return dict.
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result['result'] = {}
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del tmp # tmp no longer has any effect
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args = self._task.args
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self._validate_args(args)
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# Modify the state as necessary.
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self._set_physnet_idxs(args['state'], args['hypervisor_vars'])
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self._process_specs(task_vars['hostvars']['localhost'], args)
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# Return the modified state.
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result['result'] = args['state']
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return result
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def _set_physnet_idxs(self, state, hypervisor_vars):
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"""
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Set the index of each physnet for each host.
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Use the specified physnet mappings and any existing physnet indices to
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ensure the generated indices are consistent.
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"""
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for hostname, hostvars in six.iteritems(hypervisor_vars):
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# The desired mappings given in the Tenks configuration. These do
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# not include IDXs which are an implementation detail of Tenks.
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specified_mappings = hostvars['physnet_mappings']
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try:
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# The physnet indices currently in the state file.
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old_idxs = state[hostname]['physnet_indices']
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except KeyError:
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# The hypervisor is new since the last run.
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state[hostname] = {}
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old_idxs = {}
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new_idxs = {}
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next_idx = 0
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used_idxs = old_idxs.values()
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for name, dev in six.iteritems(specified_mappings):
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try:
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# We need to re-use the IDXs of any existing physnets.
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idx = old_idxs[name]
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except KeyError:
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# New physnet requires a new IDX.
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while next_idx in used_idxs:
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next_idx += 1
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used_idxs.append(next_idx)
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idx = next_idx
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finally:
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new_idxs[name] = idx
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state[hostname]['physnet_indices'] = new_idxs
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def _process_specs(self, localhost_vars, args):
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"""
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Ensure the correct nodes are present in `state`.
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Remove unnecessary nodes by marking as 'absent' and schedule new nodes
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to hypervisors such that the nodes in `state` match what's specified in
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`specs`.
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"""
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# Iterate through existing nodes, marking for deletion where necessary.
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for hyp in args['state'].values():
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# Anything already marked as 'absent' should no longer exist.
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hyp['nodes'] = [n for n in hyp.get('nodes', [])
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if n.get('state') != 'absent']
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for node in hyp['nodes']:
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if ((localhost_vars['cmd'] == 'teardown' or
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not self._tick_off_node(args['specs'], node))):
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# We need to delete this node, since it exists but does not
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# fulfil any spec.
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node['state'] = 'absent'
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if localhost_vars['cmd'] != 'teardown':
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# Now create all the required new nodes.
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self._create_nodes(localhost_vars, args)
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def _tick_off_node(self, specs, node):
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"""
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Tick off an existing node as fulfilling a node specification.
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If `node` is required in `specs`, decrement that spec's count and
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return True. Otherwise, return False.
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"""
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# Attributes that a spec and a node have to have in common for the node
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# to count as an 'instance' of the spec.
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MATCHING_ATTRS = {'type', 'ironic_config'}
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for spec in specs:
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if ((all(spec[attr] == node[attr] for attr in MATCHING_ATTRS) and
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spec['count'] > 0)):
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spec['count'] -= 1
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return True
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return False
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def _create_nodes(self, localhost_vars, args):
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"""
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Create new nodes to fulfil the specs.
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"""
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scheduler = RoundRobinScheduler(args['hypervisor_vars'],
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args['state'])
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# Anything left in specs needs to be created.
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for spec in args['specs']:
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for _ in six.moves.range(spec['count']):
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node = self._gen_node(localhost_vars, spec['type'],
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args, spec.get('ironic_config'))
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hostname, idx = scheduler.choose_host(node)
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# Set node name based on its index.
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node['name'] = "%s%d" % (args['node_name_prefix'], idx)
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# Set IPMI port using its index as an offset from the lowest
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# port.
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node['ipmi_port'] = (
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args['hypervisor_vars'][hostname][
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'ipmi_port_range_start'] + idx)
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# Set up node list structure for this host.
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args['state'].setdefault(hostname, {})
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args['state'][hostname].setdefault('nodes', [])
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args['state'][hostname]['nodes'].append(node)
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def _gen_node(self, localhost_vars, type_name, args, ironic_config=None):
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"""
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Generate a node description.
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A name will not be assigned at this point because we don't know which
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hypervisor the node will be scheduled to.
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"""
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node_type = args['node_types'][type_name]
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node = deepcopy(node_type)
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# All nodes need an Ironic driver.
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node.setdefault(
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'ironic_driver',
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localhost_vars['default_ironic_driver']
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)
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# Set the type name, for future reference.
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node['type'] = type_name
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# Sequentially number the volume names.
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for vol_idx, vol in enumerate(node['volumes']):
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vol['name'] = (
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"%s%d" % (args['vol_name_prefix'], vol_idx))
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# Ironic config is not mandatory.
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if ironic_config:
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node['ironic_config'] = ironic_config
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return node
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def _validate_args(self, args):
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if args is None:
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args = {}
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REQUIRED_ARGS = {'hypervisor_vars', 'specs', 'node_types'}
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# Var names and their defaults.
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OPTIONAL_ARGS = [
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('node_name_prefix', 'tk'),
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# state is optional, since if this is the first run there won't be
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# any yet.
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('state', {}),
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('vol_name_prefix', 'vol'),
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]
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for arg in REQUIRED_ARGS:
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if arg not in args:
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e = "The parameter '%s' must be specified." % arg
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raise AnsibleActionFail(to_text(e))
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for arg in OPTIONAL_ARGS:
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if arg[0] not in args:
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args[arg[0]] = arg[1]
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if not args['hypervisor_vars']:
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e = ("There are no hosts in the 'hypervisors' group to which we "
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"can schedule.")
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raise AnsibleActionFail(to_text(e))
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for spec in args['specs']:
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if 'type' not in spec or 'count' not in spec:
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e = ("All specs must contain a `type` and a `count`. "
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"Offending spec: %s" % spec)
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raise AnsibleActionFail(to_text(e))
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@six.add_metaclass(abc.ABCMeta)
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class Scheduler():
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"""
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Abstract class representing a 'method' of scheduling nodes to hosts.
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"""
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def __init__(self, hostvars, state):
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self.hostvars = hostvars
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self.state = state
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self._host_free_idxs = {}
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@abc.abstractmethod
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def choose_host(self, node):
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"""Abstract method to choose a host to which we can schedule `node`.
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Returns a tuple of the hostname of the chosen host and the index of
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this node on the host.
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"""
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raise NotImplementedError()
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def host_next_idx(self, hostname):
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"""
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Return the next available index for a node on this host.
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If the free indices are not cached for this host, they will be
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calculated.
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:param hostname: The name of the host in question
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:returns: The next available index, or None if none is available
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"""
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if hostname not in self._host_free_idxs:
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self._calculate_free_idxs(hostname)
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try:
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return self._host_free_idxs[hostname].pop(0)
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except IndexError:
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return None
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def host_passes(self, node, hostname):
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"""
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Perform checks to ascertain whether this host can support this node.
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"""
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# Check that the host is connected to all physical networks that the
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# node requires.
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return all(pn in self.hostvars[hostname]['physnet_mappings'].keys()
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for pn in node['physical_networks'])
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def _calculate_free_idxs(self, hostname):
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# The maximum number of nodes this host can have is the number of
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# IPMI ports it has available.
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all_idxs = six.moves.range(
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self.hostvars[hostname]['ipmi_port_range_end'] -
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self.hostvars[hostname]['ipmi_port_range_start'] + 1)
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get_idx = (
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lambda n: int(re.match(r'[A-Za-z]*([0-9]+)$', n).group(1)))
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used_idxs = {get_idx(n['name']) for n in self.state[hostname]['nodes']
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if n.get('state') != 'absent'}
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self._host_free_idxs[hostname] = sorted([i for i in all_idxs
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if i not in used_idxs])
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class RoundRobinScheduler(Scheduler):
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"""
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Schedule nodes in a round-robin fashion to hosts.
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"""
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def __init__(self, hostvars, state):
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super(RoundRobinScheduler, self).__init__(hostvars, state)
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self.hostvars = hostvars
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self._host_cycle = itertools.cycle(hostvars.keys())
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def choose_host(self, node):
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idx = None
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count = 0
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while idx is None:
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# Ensure we don't get into an infinite loop if no hosts are
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# available.
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if count >= len(self.hostvars):
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e = ("No hypervisors are left that can support the node %s."
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% node)
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raise AnsibleActionFail(to_text(e))
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count += 1
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hostname = next(self._host_cycle)
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if self.host_passes(node, hostname):
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idx = self.host_next_idx(hostname)
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return hostname, idx
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