3 from __future__ import absolute_import, print_function
5 from operator import attrgetter
7 import libcloud.common.types as cloud_types
8 from libcloud.compute.base import NodeDriver
10 from ...config import NETWORK_ERRORS
12 class BaseComputeNodeDriver(object):
13 """Abstract base class for compute node drivers.
15 libcloud drivers abstract away many of the differences between
16 cloud providers, but managing compute nodes requires some
17 cloud-specific features (e.g., keeping track of node FQDNs and
18 boot times). Compute node drivers are responsible for translating
19 the node manager's cloud requests to a specific cloud's
22 Subclasses must implement arvados_create_kwargs, sync_node,
23 node_fqdn, and node_start_time.
25 CLOUD_ERRORS = NETWORK_ERRORS + (cloud_types.LibcloudError,)
27 def __init__(self, auth_kwargs, list_kwargs, create_kwargs, driver_class):
28 """Base initializer for compute node drivers.
31 * auth_kwargs: A dictionary of arguments that are passed into the
32 driver_class constructor to instantiate a libcloud driver.
33 * list_kwargs: A dictionary of arguments that are passed to the
34 libcloud driver's list_nodes method to return the list of compute
36 * create_kwargs: A dictionary of arguments that are passed to the
37 libcloud driver's create_node method to create a new compute node.
38 * driver_class: The class of a libcloud driver to use.
40 self.real = driver_class(**auth_kwargs)
41 self.list_kwargs = list_kwargs
42 self.create_kwargs = create_kwargs
43 # Transform entries in create_kwargs. For each key K, if this class
44 # has an _init_K method, remove the entry and call _init_K with the
45 # corresponding value. If _init_K returns None, the entry stays out
46 # of the dictionary (we expect we're holding the value somewhere
47 # else, like an instance variable). Otherwise, _init_K returns a
48 # key-value tuple pair, and we add that entry to create_kwargs.
49 for key in self.create_kwargs.keys():
50 init_method = getattr(self, '_init_' + key, None)
51 if init_method is not None:
52 new_pair = init_method(self.create_kwargs.pop(key))
53 if new_pair is not None:
54 self.create_kwargs[new_pair[0]] = new_pair[1]
56 def _init_ping_host(self, ping_host):
57 self.ping_host = ping_host
59 def search_for(self, term, list_method, key=attrgetter('id')):
60 """Return one matching item from a list of cloud objects.
62 Raises ValueError if the number of matching objects is not exactly 1.
65 * term: The value that identifies a matching item.
66 * list_method: A string that names the method to call on this
67 instance's libcloud driver for a list of objects.
68 * key: A function that accepts a cloud object and returns a
69 value search for a `term` match on each item. Returns the
70 object's 'id' attribute by default.
72 cache_key = (list_method, term)
73 if cache_key not in self.SEARCH_CACHE:
74 results = [item for item in getattr(self.real, list_method)()
78 raise ValueError("{} returned {} results for '{}'".format(
79 list_method, count, term))
80 self.SEARCH_CACHE[cache_key] = results[0]
81 return self.SEARCH_CACHE[cache_key]
84 return self.real.list_nodes(**self.list_kwargs)
86 def arvados_create_kwargs(self, arvados_node):
87 """Return dynamic keyword arguments for create_node.
89 Subclasses must override this method. It should return a dictionary
90 of keyword arguments to pass to the libcloud driver's create_node
91 method. These arguments will extend the static arguments in
95 * arvados_node: The Arvados node record that will be associated
96 with this cloud node, as returned from the API server.
98 raise NotImplementedError("BaseComputeNodeDriver.arvados_create_kwargs")
100 def _make_ping_url(self, arvados_node):
101 return 'https://{}/arvados/v1/nodes/{}/ping?ping_secret={}'.format(
102 self.ping_host, arvados_node['uuid'],
103 arvados_node['info']['ping_secret'])
105 def create_node(self, size, arvados_node):
106 kwargs = self.create_kwargs.copy()
107 kwargs.update(self.arvados_create_kwargs(arvados_node))
108 kwargs['size'] = size
109 return self.real.create_node(**kwargs)
111 def post_create_node(self, cloud_node):
112 # ComputeNodeSetupActor calls this method after the cloud node is
113 # created. Any setup tasks that need to happen afterward (e.g.,
114 # tagging) should be done in this method.
117 def sync_node(self, cloud_node, arvados_node):
118 # When a compute node first pings the API server, the API server
119 # will automatically assign some attributes on the corresponding
120 # node record, like hostname. This method should propagate that
121 # information back to the cloud node appropriately.
122 raise NotImplementedError("BaseComputeNodeDriver.sync_node")
125 def node_fqdn(cls, node):
126 # This method should return the FQDN of the node object argument.
127 # Different clouds store this in different places.
128 raise NotImplementedError("BaseComputeNodeDriver.node_fqdn")
131 def node_start_time(cls, node):
132 # This method should return the time the node was started, in
133 # seconds since the epoch UTC.
134 raise NotImplementedError("BaseComputeNodeDriver.node_start_time")
137 def is_cloud_exception(cls, exception):
138 # libcloud compute drivers typically raise bare Exceptions to
139 # represent API errors. Return True for any exception that is
140 # exactly an Exception, or a better-known higher-level exception.
141 return (isinstance(exception, cls.CLOUD_ERRORS) or
142 type(exception) is Exception)
144 # Now that we've defined all our own methods, delegate generic, public
145 # attributes of libcloud drivers that we haven't defined ourselves.
146 def _delegate_to_real(attr_name):
148 lambda self: getattr(self.real, attr_name),
149 lambda self, value: setattr(self.real, attr_name, value),
150 doc=getattr(getattr(NodeDriver, attr_name), '__doc__', None))
153 for _attr_name in dir(NodeDriver):
154 if (not _attr_name.startswith('_')) and (_attr_name not in _locals):
155 _locals[_attr_name] = _delegate_to_real(_attr_name)