[WIP] Solve some concurrency issues

docs/LagoInitFile.rst

@@ -164,12 +164,15 @@ domains
 
 nets
 ----
-``<name>``: The name of the network.
+``<name>``: The name of the network, should be an alphanumeric string.
+            Currently we do not enforce that it is only alphanumeric,
+            but we might do so in the future.
 
     type(string)
         Type of the network. May be `nat` or `bridge`.
 
 
+
 .. _Templates: Templates.html
 .. _`virt-customize`: http://libguestfs.org/virt-customize.1.html
 .. _lago-ost-plugin: https://github.com/lago-project/lago-ost-plugin/blob/master/setup.cfg

docs/conf.py

@@ -39,6 +39,7 @@
 # expected with no need to download them (some are not in pip even)
 autodoc_mock_imports = [
     'enum',
+    'future',
     'guestfs',
     'libvirt',
     'lockfile',

lago/prefix.py

@@ -32,6 +32,7 @@
 import uuid
 import warnings
 import pkg_resources
+from hashlib import sha256
 from os.path import join
 from plugins.output import YAMLOutFormatPlugin
 
@@ -130,6 +131,53 @@ def metadata(self):
                 self._metadata = {}
         return self._metadata
 
+    @property
+    @sdk_utils.expose
+    def uuid(self):
+        """
+        The prefix UUID
+
+        Returns:
+            str: UUID4
+        """
+        if not os.path.isfile(self.paths.uuid()):
+            raise utils.LagoException(
+                'No UUID found at {0}'.format(os.paths.uuid())
+            )
+        with open(self.paths.uuid(), 'r') as uuid_fd:
+            uuid = uuid_fd.read().strip()
+        return str(uuid)
+
+    @sdk_utils.expose
+    def prefixed_name(self, unprefixed_name, max_length=15):
+        """
+        Returns an alpha-numeric identifier for the `unprefixed_name` specific
+            to this prefix, it is composed from:
+                (last 8 chars from the prefix uuid) concatenated with
+                (last min(max_length-8,72) chars of the SHA256 of
+                    `unprefixed_name`)
+        Note that it is highly recommended to use the maximal length
+        possible(72), otherwise, hash collisions are more likely to happen.
+
+
+        Args:
+            unprefixed_name(str): Name to hash
+            max_length(int): Maximum identifier length to return. 0 means 15.
+                Other than 0 allowed values are in range [11, 15].
+        Returns:
+            str: prefix identifier for `unprefixed_name`
+        """
+
+        if max_length < 11:
+            raise utils.LagoException('max length must be larger than 11')
+
+        hashed_name = sha256(unprefixed_name)
+
+        return '{uuid}{hashed}'.format(
+            uuid=self.uuid[:8],
+            hashed=hashed_name.hexdigest()[:min(max_length - 8, 72)]
+        )
+
     def _save_metadata(self):
         """
         Write this prefix metadata to disk
@@ -181,19 +229,21 @@ def _create_ssh_keys(self):
             )
 
     @log_task('Initialize prefix')
-    def initialize(self):
+    def initialize(self, skip_ssh=False):
         """
         Initialize this prefix, this includes creating the destination path,
         and creating the uuid for the prefix, for any other actions see
         :func:`Prefix.virt_conf`
 
         Will safely roll back if any of those steps fail
 
+        Args:
+            skip_ssh(bool): Skip generating SSH keys
         Returns:
             None
 
         Raises:
-            RuntimeError: If it fails to create the prefix dir
+            :exc:`LagoInitException`: If it fails to create the prefix dir
         """
         prefix = self.paths.prefix_path()
         os.environ['LAGO_PREFIX_PATH'] = prefix
@@ -204,17 +254,17 @@ def initialize(self):
                 try:
                     os.mkdir(prefix)
                 except OSError as error:
-                    raise RuntimeError(
+                    raise LagoInitException(
                         'Could not create prefix at %s:\n%s' % (prefix, error)
                     )
             rollback.prependDefer(shutil.rmtree, prefix)
 
             with open(self.paths.uuid(), 'w') as f, \
-                    LogTask('Generate prefix uuid'):
-                f.write(uuid.uuid1().hex)
-
-            with LogTask('Create ssh keys'):
-                self._create_ssh_keys()
+                    LogTask('Generate prefix uuid4'):
+                f.write(uuid.uuid4().hex)
+            if not skip_ssh:
+                with LogTask('Create ssh keys'):
+                    self._create_ssh_keys()
 
             with LogTask('Tag prefix as initialized'):
                 with open(self.paths.prefix_lagofile(), 'w') as fd:

lago/providers/libvirt/network.py

@@ -38,7 +38,7 @@ def __init__(self, env, spec, compat):
         self._env = env
         libvirt_url = config.get('libvirt_url')
         self.libvirt_con = libvirt_utils.get_libvirt_connection(
-            name=env.uuid + libvirt_url,
+            name=env.prefix.prefixed_name(libvirt_url),
             libvirt_url=libvirt_url,
         )
         self._spec = spec
@@ -79,8 +79,10 @@ def resolve(self, name):
     def mapping(self):
         return self._spec['mapping']
 
-    def _libvirt_name(self):
-        return self._env.prefixed_name(self.name(), max_length=15)
+    def _libvirt_name(self, max_length=15):
+        return self._env.prefix.prefixed_name(
+            self.name(), max_length=max_length
+        )
 
     def _libvirt_xml(self):
         raise NotImplementedError(
@@ -184,7 +186,7 @@ def _libvirt_xml(self):
 
         replacements = {
             '@NAME@': self._libvirt_name(),
-            '@BR_NAME@': ('%s-nic' % self._libvirt_name())[:12],
+            '@BR_NAME@': 'b' + self._libvirt_name(11),
             '@GW_ADDR@': self.gw(),
             '@SUBNET@': subnet
         }

lago/providers/libvirt/vm.py

@@ -56,7 +56,7 @@ def __init__(self, vm):
         self._has_guestfs = 'lago.guestfs_tools' in sys.modules
         libvirt_url = config.get('libvirt_url')
         self.libvirt_con = libvirt_utils.get_libvirt_connection(
-            name=self.vm.virt_env.uuid + libvirt_url,
+            name=vm.virt_env.prefix.prefixed_name(libvirt_url),
             libvirt_url=libvirt_url,
         )
         self._libvirt_ver = self.libvirt_con.getLibVersion()
@@ -468,7 +468,7 @@ def cpu_vendor(self):
         return self._cpu.vendor
 
     def _libvirt_name(self):
-        return self.vm.virt_env.prefixed_name(self.vm.name())
+        return self.vm.virt_env.prefix.prefixed_name(self.vm.name())
 
     def _get_qemu_kvm_path(self):
         qemu_kvm_path = self._caps.findtext(
@@ -590,9 +590,8 @@ def _libvirt_xml(self):
             interface.append(
                 ET.Element(
                     'source',
-                    network=self.vm.virt_env.prefixed_name(
-                        dev_spec['net'], max_length=15
-                    ),
+                    network=self.vm.virt_env.prefix.
+                    prefixed_name(dev_spec['net']),
                 ),
             )
             interface.append(

lago/virt.py

@@ -19,12 +19,9 @@
 #
 from copy import deepcopy
 import functools
-import hashlib
 import json
 import logging
 import os
-import uuid
-
 import yaml
 
 from lago import log_utils, plugins, utils
@@ -37,34 +34,6 @@
 log_task = functools.partial(log_utils.log_task, logger=LOGGER)
 
 
-def _gen_ssh_command_id():
-    return uuid.uuid1().hex[:8]
-
-
-def _guestfs_copy_path(g, guest_path, host_path):
-    if g.is_file(guest_path):
-        with open(host_path, 'w') as f:
-            f.write(g.read_file(guest_path))
-    elif g.is_dir(guest_path):
-        os.mkdir(host_path)
-        for path in g.ls(guest_path):
-            _guestfs_copy_path(
-                g,
-                os.path.join(
-                    guest_path,
-                    path,
-                ),
-                os.path.join(host_path, os.path.basename(path)),
-            )
-
-
-def _path_to_xml(basename):
-    return os.path.join(
-        os.path.dirname(__file__),
-        basename,
-    )
-
-
 class VirtEnv(object):
     '''Env properties:
     * prefix
@@ -81,12 +50,9 @@ def __init__(self, prefix, vm_specs, net_specs):
         )
         self.prefix = prefix
 
-        with open(self.prefix.paths.uuid(), 'r') as uuid_fd:
-            self.uuid = uuid_fd.read().strip()
-
         libvirt_url = config.get('libvirt_url')
         self.libvirt_con = libvirt_utils.get_libvirt_connection(
-            name=self.uuid + libvirt_url,
+            name=self.prefix.prefixed_name(libvirt_url),
             libvirt_url=libvirt_url,
         )
         self._nets = {}
@@ -118,41 +84,6 @@ def _create_vm(self, vm_spec):
         vm_spec['vm-type'] = vm_type_name
         return vm_type(self, vm_spec)
 
-    def prefixed_name(self, unprefixed_name, max_length=0):
-        """
-        Returns a uuid pefixed identifier
-
-        Args:
-            unprefixed_name(str): Name to add a prefix to
-            max_length(int): maximum length of the resultant prefixed name,
-                will adapt the given name and the length of the uuid ot fit it
-
-        Returns:
-            str: prefixed identifier for the given unprefixed name
-        """
-        if max_length == 0:
-            prefixed_name = '%s-%s' % (self.uuid[:8], unprefixed_name)
-        else:
-            if max_length < 6:
-                raise RuntimeError(
-                    "Can't prefix with less than 6 chars (%s)" %
-                    unprefixed_name
-                )
-            if max_length < 16:
-                _uuid = self.uuid[:4]
-            else:
-                _uuid = self.uuid[:8]
-
-            name_max_length = max_length - len(_uuid) - 1
-
-            if name_max_length < len(unprefixed_name):
-                hashed_name = hashlib.sha1(unprefixed_name).hexdigest()
-                unprefixed_name = hashed_name[:name_max_length]
-
-            prefixed_name = '%s-%s' % (_uuid, unprefixed_name)
-
-        return prefixed_name
-
     def virt_path(self, *args):
         return self.prefix.paths.virt(*args)