Source Code for Module virtualization.domain_directory

  1  # 
  2  # Copyright (c) 2008--2013 Red Hat, Inc. 
  3  # 
  4  # This software is licensed to you under the GNU General Public License, 
  5  # version 2 (GPLv2). There is NO WARRANTY for this software, express or 
  6  # implied, including the implied warranties of MERCHANTABILITY or FITNESS 
  7  # FOR A PARTICULAR PURPOSE. You should have received a copy of GPLv2 
  8  # along with this software; if not, see 
  9  # http://www.gnu.org/licenses/old-licenses/gpl-2.0.txt. 
 10  # 
 11  # Red Hat trademarks are not licensed under GPLv2. No permission is 
 12  # granted to use or replicate Red Hat trademarks that are incorporated 
 13  # in this software or its documentation. 
 14  # 
 15   
 16  import binascii 
 17  import os 
 18  import sys 
 19   
 20  try: 
 21      import libvirt 
 22  except ImportError: 
 23      # There might not be a libvirt; we won't die here so that other modules 
 24      # who import us can exit gracefully. 
 25      libvirt = None 
 26   
 27  from rhn.i18n import sstr 
 28   
 29  from virtualization.domain_config import DomainConfig 
 30  from virtualization.errors        import VirtualizationException 
 31  from virtualization.util          import dehyphenize_uuid, \ 
 32                                           hyphenize_uuid,   \ 
 33                                           is_host_uuid 
 34   
 35  ############################################################################### 
 36  # Constants 
 37  ############################################################################### 
 38   
 39  CONFIG_DIR = '/etc/sysconfig/rhn/virt' 
 40  STANDARD_CONFIG_TEMPLATE = """ 
 41      <domain type='xen'> 
 42          <name>%(name)s</name> 
 43          <bootloader>/usr/bin/pygrub</bootloader> 
 44          <memory>%(mem_kb)s</memory> 
 45          <vcpu>%(vcpus)s</vcpu> 
 46          <uuid>%(uuid)s</uuid> 
 47          <on_reboot>restart</on_reboot> 
 48          <on_poweroff>destroy</on_poweroff> 
 49          <on_crash>preserve</on_crash> 
 50          <devices> 
 51              <disk type='file'> 
 52                  <source file='%(disk)s'/> 
 53                  <target dev='xvda'/> 
 54              </disk> 
 55              <interface type='bridge'> 
 56                  <source bridge='xenbr0'/> 
 57                  <mac address='%(mac)s'/> 
 58                  <script path='/etc/xen/scripts/vif-bridge'/> 
 59              </interface> 
 60          </devices> 
 61  </domain> 
 62  """ 
 63   
 64  ############################################################################### 
 65  # Classes 
 66  ############################################################################### 
 67   
 68 -class DomainDirectory: 
 69   
 70 -    def __init__(self): 
 71          self.__path = CONFIG_DIR 
 72          self.conn = libvirt.openReadOnly(None) 
 73          if not self.conn: 
 74              raise VirtualizationException("Failed to open connection to hypervisor.") 
 75   
 76 -    def get_config_path(self, uuid): 
 77          cfg_filename = "%s.xml" % uuid 
 78          cfg_pathname = os.path.join(self.__path, cfg_filename) 
 79          return cfg_pathname 
 80   
 81 -    def is_known_config(self, uuid): 
 82          """ 
 83          Returns true if a config for the given uuid is saved in the directory. 
 84          """ 
 85          path = self.get_config_path(uuid) 
 86          return os.path.exists(path) 
 87   
 88 -    def load_config(self, uuid): 
 89          """ 
 90          This function loads a domain's configuration by its UUID.  A 
 91          DomainConfig object is returned. 
 92          """ 
 93          return DomainConfig(self.__path, uuid) 
 94   
 95 -    def create_standard_config(self, uuid, name, mem_kb, vcpus, disk, mac): 
 96          # First, populate the XML with the appropriate values. 
 97          boot_params = { 'name'       : name, 
 98                          'mem_kb'     : mem_kb, 
 99                          'vcpus'      : vcpus, 
100                          'uuid'       : hyphenize_uuid(uuid), 
101                          'disk'       : disk, 
102                          'mac'        : mac } 
103   
104          xml = STANDARD_CONFIG_TEMPLATE % boot_params 
105   
106          self.__write_xml_file(uuid, xml) 
107   
108 -    def save_unknown_domain_configs(self, domain_uuids): 
109          """ 
110          This function saves the configuration for any domains whose UUIDs are 
111          passed in the domain_uuids list.  If the UUID is already known, it is 
112          skipped. 
113          """ 
114   
115          for uuid in domain_uuids: 
116   
117              uuid = sstr(uuid) 
118              # If we already have a config for this uuid, skip it.  Also, don't 
119              # try to figure out a config for a host UUID. 
120              if not is_host_uuid(uuid) and not self.is_known_config(uuid): 
121   
122                  # The UUID is a formatted string.  Turn it back into a number, 
123                  # since that's what libvirt wants. 
124                  dehyphenized_uuid = dehyphenize_uuid(uuid) 
125                  uuid_as_num = binascii.unhexlify(dehyphenized_uuid) 
126   
127                  # Lookup the domain by its uuid. 
128                  try: 
129                      domain = self.conn.lookupByUUID(uuid_as_num) 
130                  except libvirt.libvirtError: 
131                      lve = sys.exc_info()[1] 
132                      raise VirtualizationException("Failed to obtain handle to domain %s: %s" % (uuid, repr(lve))) 
133   
134                  # Now grab the XML description of the configuration. 
135                  xml = domain.XMLDesc(0) 
136   
137                  # Write the xml out to a file so that we can load it into our 
138                  # abstract DomainConfig object and manipulate it easily. 
139                  cfg_file_path = self.__write_xml_file(uuid, xml) 
140                  new_config = DomainConfig(self.__path, uuid) 
141   
142                  # Don't record the config this time if the domain is 
143                  # installing; we don't want to restart the domain later and 
144                  # make it re-install itself. 
145                  if not new_config.isInstallerConfig(): 
146   
147                      # Now we'll reformat the configuration object so that it's 
148                      # valid the next time this domain runs.. 
149                      self.__fixup_config_for_restart(new_config) 
150   
151                      # The config is now prepared.  Save it and move on to the 
152                      # next uuid. 
153                      new_config.save() 
154   
155                  else: 
156                      # Remove the config file we just wrote. 
157                      os.unlink(cfg_file_path) 
158   
159 -    def __fixup_config_for_restart(self, config): 
160          """ 
161          This function edits the given configuration so that it can be used in 
162          subsequent calls to libvirt's createLinux call.  Specifically, the 
163          following modifications are made: 
164   
165              - Remove the "id" attribute from the <domain> tag.  The "id" is 
166                whatever the hypervisor wants to assign to it, so we should not 
167                try to assign it explicitly. 
168   
169              - Determine whether the config contains an <os> section. 
170                  - If it does, check whether the kernel and the initrd files 
171                    it refers to actually exist on disk. 
172                      - If so, do nothing. 
173                      - If not, remove the entire <os> section and insert a 
174                        <bootloader> section if one does not yet exist.  These 
175                        files might not exist if the instance was started by xm 
176                        using a bootloader such as pygrub, which makes temporary 
177                        copies of the kernel & initrd and then removes them after 
178                        starting the instance. 
179                  - If it does not, ensure there is a <bootloader> section or 
180                    add one if needed. 
181          """ 
182          # Remove the domain ID from the XML.  This is a runtime value that 
183          # should not be assigned statically. 
184          if config.hasConfigItem(DomainConfig.DOMAIN_ID): 
185              config.removeConfigItem(DomainConfig.DOMAIN_ID) 
186   
187          if self.conn.getType() == 'QEMU': 
188              # Dont worry about bootloader if its kvm 
189              return 
190   
191          boot_images_exist = 0 
192   
193          if config.hasConfigItem(DomainConfig.KERNEL_PATH) and \ 
194             config.hasConfigItem(DomainConfig.RAMDISK_PATH): 
195   
196              kernel_path = config.getConfigItem(DomainConfig.KERNEL_PATH) 
197              ramdisk_path = config.getConfigItem(DomainConfig.KERNEL_PATH) 
198   
199              if os.path.exists(kernel_path) and os.path.exists(ramdisk_path): 
200                  boot_images_exist = 1 
201   
202          # If we've determined that the referenced boot images do not exist, 
203          # remove the OS section and insert a bootloader piece. 
204          if not boot_images_exist: 
205              if config.hasConfigItem(DomainConfig.OS): 
206                  config.removeConfigItem(DomainConfig.OS) 
207   
208              if not config.hasConfigItem(DomainConfig.BOOTLOADER): 
209                  config.setConfigItem(DomainConfig.BOOTLOADER, "/usr/bin/pygrub") 
210   
211   
212 -    def __write_xml_file(self, uuid, xml): 
213          cfg_pathname = self.get_config_path(uuid) 
214          cfg_file = open(cfg_pathname, "w") 
215          cfg_file.write(xml.strip()) 
216          cfg_file.close() 
217   
218          return cfg_pathname 
219