Enable tests to have host-specific parameters

server/site_host_attributes.py

+# Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import logging, os, utils
+
+# Host attributes are specified a strings with the format:
+#   <key>{,<value>}?
+#
+# A machine may have a list of strings for attributes like:
+#
+#   ['has_80211n,True',
+#    'has_ssd,False',
+#    'drive_kind,string,ssd,1']
+#
+# A legal attribute has the pattern:
+#   <name>,<kind>(,<extra>)?
+#
+# Name can be any legal python identifier.  Kind may be any of 'string',
+# 'True', or 'False'.  Only if kind is string can there be extra data.
+#
+# Strings which are not legal attributes are ignored.
+#
+# Given the above list of attributes, you can use the syntax:
+#   host_attributes.drive_kind => 'ssd,1'
+#   host_attributes.has_80211n => True
+#   host_attributes.has_ssd => False
+#   host_attributes.unknown_attribute => raise KeyError
+#
+# Machine attributes can be specified in two ways.
+#
+# If you create private_host_attributes_config.py and
+# private_host_attributes there, we will use it when possible instead of
+# using the server front-end.
+#
+# Example configuration:
+#   private_host_attributes = {
+#     "myserver": ["has_80211n,True",
+#                  "has_resume_bug,False"]
+#   }
+#
+# We also consult the AFE database for its labels which are all treated
+# as host attribute strings defined above.  Illegal strings are ignored.
+#
+
+private_host_attributes = utils.import_site_symbol(
+    __file__,
+    'autotest_lib.server.private_host_attributes_config',
+    'private_host_attributes', dummy={})
+
+try:
+    settings = 'autotest_lib.frontend.settings'
+    os.environ['DJANGO_SETTINGS_MODULE'] = settings
+    from autotest_lib.frontend.afe import models
+    has_models = True
+except ImportError, e:
+    has_models = False
+
+
+_DEFAULT_ATTRIBUTES = [
+    'has_80211n,True',
+    'has_chromeos_firmware,False',
+    'has_resume_bug,False',
+    'has_ssd,True',
+    ]
+
+
+class HostAttributes(object):
+
+
+    def __init__(self, host):
+        """
+        Create an instance of HostAttribute for the given hostname.
+        We look up the host in both the hardcoded configuration and
+        the AFE models if they can be found.
+        """
+        self._add_attributes(_DEFAULT_ATTRIBUTES)
+        if host in private_host_attributes:
+            self._add_attributes(private_host_attributes[host])
+        if has_models:
+            host_obj = models.Host.valid_objects.get(hostname=host)
+            self._add_attributes(host_obj.labels.all())
+        for key, value in self.__dict__.items():
+            logging.info('Host attribute: %s => %s', key, value)
+
+
+    def _add_attributes(self, attributes):
+        for attribute in attributes:
+            splitnames = attribute.split(',')
+            value = ','.join(splitnames[1:])
+            if value == 'True':
+                value = True
+            elif value == 'False':
+                value = False
+            elif splitnames[1] == 'string':
+                value = ','.join(splitnames[2:])
+            else:
+                log.info('Non-attribute string "%s" is ignored' % attribute)
+                continue
+            setattr(self, splitnames[0], value)