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, NodeAuthSSHKey
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 _init_ssh_key(self, filename):
60 with open(filename) as ssh_file:
61 key = NodeAuthSSHKey(ssh_file.read())
64 def search_for(self, term, list_method, key=attrgetter('id'), **kwargs):
65 """Return one matching item from a list of cloud objects.
67 Raises ValueError if the number of matching objects is not exactly 1.
70 * term: The value that identifies a matching item.
71 * list_method: A string that names the method to call on this
72 instance's libcloud driver for a list of objects.
73 * key: A function that accepts a cloud object and returns a
74 value search for a `term` match on each item. Returns the
75 object's 'id' attribute by default.
77 cache_key = (list_method, term)
78 if cache_key not in self.SEARCH_CACHE:
79 items = getattr(self.real, list_method)(**kwargs)
80 results = [item for item in items
84 raise ValueError("{} returned {} results for '{}'".format(
85 list_method, count, term))
86 self.SEARCH_CACHE[cache_key] = results[0]
87 return self.SEARCH_CACHE[cache_key]
90 return self.real.list_nodes(**self.list_kwargs)
92 def arvados_create_kwargs(self, arvados_node):
93 """Return dynamic keyword arguments for create_node.
95 Subclasses must override this method. It should return a dictionary
96 of keyword arguments to pass to the libcloud driver's create_node
97 method. These arguments will extend the static arguments in
101 * arvados_node: The Arvados node record that will be associated
102 with this cloud node, as returned from the API server.
104 raise NotImplementedError("BaseComputeNodeDriver.arvados_create_kwargs")
106 def broken(self, cloud_node):
107 """Return true if libcloud has indicated the node is in a "broken" state."""
110 def _make_ping_url(self, arvados_node):
111 return 'https://{}/arvados/v1/nodes/{}/ping?ping_secret={}'.format(
112 self.ping_host, arvados_node['uuid'],
113 arvados_node['info']['ping_secret'])
115 def create_node(self, size, arvados_node):
116 kwargs = self.create_kwargs.copy()
117 kwargs.update(self.arvados_create_kwargs(arvados_node))
118 kwargs['size'] = size
119 return self.real.create_node(**kwargs)
121 def post_create_node(self, cloud_node):
122 # ComputeNodeSetupActor calls this method after the cloud node is
123 # created. Any setup tasks that need to happen afterward (e.g.,
124 # tagging) should be done in this method.
127 def sync_node(self, cloud_node, arvados_node):
128 # When a compute node first pings the API server, the API server
129 # will automatically assign some attributes on the corresponding
130 # node record, like hostname. This method should propagate that
131 # information back to the cloud node appropriately.
132 raise NotImplementedError("BaseComputeNodeDriver.sync_node")
135 def node_fqdn(cls, node):
136 # This method should return the FQDN of the node object argument.
137 # Different clouds store this in different places.
138 raise NotImplementedError("BaseComputeNodeDriver.node_fqdn")
141 def node_start_time(cls, node):
142 # This method should return the time the node was started, in
143 # seconds since the epoch UTC.
144 raise NotImplementedError("BaseComputeNodeDriver.node_start_time")
147 def is_cloud_exception(cls, exception):
148 # libcloud compute drivers typically raise bare Exceptions to
149 # represent API errors. Return True for any exception that is
150 # exactly an Exception, or a better-known higher-level exception.
151 return (isinstance(exception, cls.CLOUD_ERRORS) or
152 type(exception) is Exception)
154 # Now that we've defined all our own methods, delegate generic, public
155 # attributes of libcloud drivers that we haven't defined ourselves.
156 def _delegate_to_real(attr_name):
158 lambda self: getattr(self.real, attr_name),
159 lambda self, value: setattr(self.real, attr_name, value),
160 doc=getattr(getattr(NodeDriver, attr_name), '__doc__', None))
163 for _attr_name in dir(NodeDriver):
164 if (not _attr_name.startswith('_')) and (_attr_name not in _locals):
165 _locals[_attr_name] = _delegate_to_real(_attr_name)