]> scripts.mit.edu Git - wizard.git/blobdiff - wizard/deploy.py
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[wizard.git] / wizard / deploy.py
index 3ae65e3b2c9d4206652b0278758a14e5937ff0ef..507fdf314b78eee89b6c1581213eb7b393ee7d49 100644 (file)
@@ -1,30 +1,39 @@
 """
 Object model for querying information and manipulating deployments
-of autoinstalls.  Every :class:`Deployment` has an :class:`ApplicationVersion`
-which in turn has an :class:`Application`.
+of autoinstalls.  Every :class:`Deployment` has an :class:`app.ApplicationVersion`
+which in turn has an :class:`app.Application`.
 """
 
 import os.path
 import fileinput
-import dateutil.parser
-import distutils.version
+import logging
+import decorator
+import datetime
 import tempfile
+import time
+import traceback
+import shutil
+import errno
+import pkg_resources
+import urlparse
 
 import wizard
-from wizard import git, log, util
+from wizard import app, git, old_log, shell, sql, util
 
 ## -- Global Functions --
 
-def get_install_lines(versions_store):
+def get_install_lines(versions_store, user=None):
     """
     Low level function that retrieves a list of lines from the
     :term:`versions store` that can be passed to :meth:`Deployment.parse`.
     """
     if os.path.isfile(versions_store):
         return fileinput.input([versions_store])
-    return fileinput.input([versions_store + "/" + f for f in os.listdir(versions_store)])
+    if user:
+        return fileinput.input([versions_store + "/" + user])
+    return fileinput.input([versions_store + "/" + f for f in sorted(os.listdir(versions_store))])
 
-def parse_install_lines(show, versions_store, yield_errors = False):
+def parse_install_lines(show, versions_store, yield_errors = False, user = None):
     """
     Generator function for iterating through all autoinstalls.
     Each item is an instance of :class:`Deployment`, or possibly
@@ -33,14 +42,24 @@ def parse_install_lines(show, versions_store, yield_errors = False):
     or ``app-1.2.3`` in ``show``.  This function may generate
     log output.
     """
-    if not show: show = applications()
-    show = frozenset(show)
-    for line in get_install_lines(versions_store):
+    if not show:
+        show = app.applications()
+    elif isinstance(show, str):
+        # otherwise, frozenset will treat string as an iterable
+        show = frozenset([show])
+    else:
+        show = frozenset(show)
+    for line in get_install_lines(versions_store, user):
         # construction
         try:
             d = Deployment.parse(line)
             name = d.application.name
-        except NoSuchApplication as e:
+        except app.NoSuchApplication as e:
+            if not e.location:
+                try:
+                    e.location = line.split(':')[0]
+                except IndexError:
+                    e.location = line
             if yield_errors:
                 yield e
             continue
@@ -49,22 +68,78 @@ def parse_install_lines(show, versions_store, yield_errors = False):
             logging.warning("Error with '%s'" % line.rstrip())
             continue
         # filter
-        if name + "-" + str(d.version) in show or name in show:
+        if name + "-" + util.truncate(str(d.version)) in show or name in show:
             pass
         else:
             continue
         # yield
         yield d
 
+def web(dir, url=None):
+    """
+    Attempts to determine the URL a directory would be web-accessible at.
+    If ``url`` is specified, automatically use it.  Returns a generator which
+    produces a list of candidate urls.
+
+    This function implements a plugin interface named :ref:`wizard.deploy.web`.
+    """
+    if url:
+        if isinstance(url, str):
+            url = urlparse.urlparse(url)
+        logging.info("wizard.deploy.web: Using default URL %s", url)
+        yield url
+        return
+
+    for entry in pkg_resources.iter_entry_points("wizard.deploy.web"):
+        logging.debug("wizard.deploy.web: Processing %s", entry)
+        f = entry.load()
+        for r in f(dir):
+            if isinstance(r, str):
+                r = urlparse.urlparse(r)
+            logging.info("wizard.deploy.web: Using plugin-supplied URL %s", r)
+            yield r
+
+    # try the environment
+    host = os.getenv("WIZARD_WEB_HOST")
+    path = os.getenv("WIZARD_WEB_PATH")
+    if host is not None and path is not None:
+        r = urlparse.ParseResult(
+                "http",
+                host,
+                path.rstrip('/'),
+                "", "", "")
+        logging.info("wizard.deploy.web: Using environment URL %s", r)
+        yield r
+
+    logging.info("wizard.deploy.web: Exhausted URLs")
+
 ## -- Model Objects --
 
+@decorator.decorator
+def chdir_to_location(f, self, *args, **kwargs):
+    """
+    Decorator for making a function have working directory
+    :attr:`Deployment.location`.
+    """
+    with util.ChangeDirectory(self.location):
+        return f(self, *args, **kwargs)
+
 class Deployment(object):
     """
-    Represents a deployment of an autoinstall, e.g. directory in a user's
-    web_scripts that has ``.scripts`` directory or ``.scripts-version``
-    file in it.  Supply ``version`` with an :class:`ApplicationVersion` only if
-    you were reading from the :term:`versions store` and care about
-    speed (data from there can be stale).
+    Represents a deployment of an autoinstall, e.g. directory that has a
+    ``.wizard`` directory in it.  Supply ``version`` with an
+    :class:`ApplicationVersion` only if you were reading from the
+    :term:`versions store` and care about speed (data from there can be
+    stale).
+
+    The Deployment interface is somewhat neutered, so you may
+    want to use :class:`WorkingCopy` or :class:`ProductionCopy` for
+    more powerful operations.
+
+    .. note::
+
+        For legacy purposes, deployments can also be marked by a
+        ``.scripts`` directory or a ``.scripts-version`` file.
     """
     #: Absolute path to the deployment
     location = None
@@ -73,7 +148,26 @@ class Deployment(object):
         self._app_version = version
         # some cache variables
         self._read_cache = {}
-        self._log = None
+        self._old_log = None
+        self._dsn = None
+        self._url = None
+        self._urlGen = None
+        self._wizard_dir = None
+    def invalidateCache(self):
+        """
+        Invalidates all cached variables.  This currently applies to
+        :attr:`app_version`, :attr:`old_log` and :meth:`read`.
+        """
+        self._app_version = None
+        self._read_cache = {}
+        self._old_log = None
+    def setAppVersion(self, app_version):
+        """
+        Manually resets the application version; useful if the working
+        copy is off in space (i.e. not anchored to something we can
+        git describe off of) or there is no metadata to be heard of.
+        """
+        self._app_version = app_version
     def read(self, file, force = False):
         """
         Reads a file's contents, possibly from cache unless ``force``
@@ -92,72 +186,158 @@ class Deployment(object):
         and local configuration.
         """
         return self.application.extract(self)
-    def parametrize(self, dir):
-        """
-        Edits files in ``dir`` to replace WIZARD_* variables with literal
-        instances.  This is used for constructing virtual merge bases, and
-        as such dir will generally not equal :attr:`location`.
-        """
-        return self.application.parametrize(self, dir)
-    def updateVersion(self, version):
-        """
-        Update the version of this deployment.
-
-        This method will update the version of this deployment in memory
-        and on disk.  It doesn't actually do an upgrade.  The version
-        string you pass here should have ``-scripts`` as a suffix.
-        """
-        self._app_version = self.application.makeVersion(version)
-        f = open(os.path.join(self.scripts_dir, 'version'), 'w')
-        f.write(self.application.name + '-' + version + "\n")
-        f.close()
-    def scriptsifyVersion(self):
-        """
-        Converts from ``v1.0`` to ``v1.0-scripts``; use at end of migration.
 
-        .. note::
+    def verify(self, no_touch=False):
+        """
+        Checks if this is an autoinstall, throws an exception if there
+        are problems.  If ``no_touch`` is ``True``, it will not attempt
+        edit the installation.
+        """
+        with util.ChangeDirectory(self.location):
+            has_git = os.path.isdir(".git")
+            has_wizard = os.path.isdir(".wizard")
+            if not has_wizard and os.path.isdir(".scripts"):
+                # LEGACY
+                os.symlink(".scripts", ".wizard")
+                has_wizard = True
+            if not has_git and has_wizard:
+                raise CorruptedAutoinstallError(self.location)
+            elif has_git and not has_wizard:
+                raise AlreadyVersionedError(self.location)
+            # LEGACY
+            elif not has_git and not has_wizard:
+                if os.path.isfile(".scripts-version"):
+                    raise NotMigratedError(self.location)
+                else:
+                    raise NotAutoinstallError(self.location)
+
+    def verifyTag(self, srv_path):
+        """
+        Checks if the purported version has a corresponding tag
+        in the upstream repository.
+        """
+        repo = self.application.repository(srv_path)
+        try:
+            shell.eval("git", "--git-dir", repo, "rev-parse", self.app_version.wizard_tag, '--')
+        except shell.CallError:
+            raise NoTagError(self.app_version.wizard_tag)
+
+    def verifyGit(self, srv_path):
+        """
+        Checks if the autoinstall's Git repository makes sense,
+        checking if the tag is parseable and corresponds to
+        a real application, and if the tag in this repository
+        corresponds to the one in the remote repository.
+        """
+        with util.ChangeDirectory(self.location):
+            repo = self.application.repository(srv_path)
+            def repo_rev_parse(tag):
+                return shell.eval("git", "--git-dir", repo, "rev-parse", tag)
+            def self_rev_parse(tag):
+                try:
+                    return shell.safeCall("git", "rev-parse", tag, strip=True)
+                except shell.CallError:
+                    raise NoLocalTagError(tag)
+            def compare_tags(tag):
+                return repo_rev_parse(tag) == self_rev_parse(tag)
+            if not compare_tags(self.app_version.pristine_tag):
+                raise InconsistentPristineTagError(self.app_version.pristine_tag)
+            if not compare_tags(self.app_version.wizard_tag):
+                # Causes remastering
+                raise InconsistentWizardTagError(self.app_version.wizard_tag)
+            parent = repo_rev_parse(self.app_version.wizard_tag)
+            merge_base = shell.safeCall("git", "merge-base", parent, "HEAD", strip=True)
+            if merge_base != parent:
+                # Causes remastering
+                raise HeadNotDescendantError(self.app_version.wizard_tag)
+
+    def verifyConfigured(self):
+        """
+        Checks if the autoinstall is configured running.
+        """
+        if not self.configured:
+            raise NotConfiguredError(self.location)
+
+    @chdir_to_location
+    def verifyVersion(self):
+        """
+        Checks if our version and the version number recorded in a file
+        are consistent.
+        """
+        real = self.detectVersion()
+        if not str(real) == self.app_version.pristine_tag.partition('-')[2]:
+            raise VersionMismatchError(real, self.version)
+
+    @chdir_to_location
+    def detectVersion(self):
+        """
+        Returns the real version, based on filesystem, of install.
+
+        Throws a :class:`VersionDetectionError` if we couldn't figure out
+        what the real version was.
+        """
+        real = self.application.detectVersion(self)
+        if not real:
+            raise VersionDetectionError
+        return real
 
-            This makes the assumption that a migration will be to
-            a ``-scripts`` tag and not a ``-scripts2`` tag.  If you botch
-            migration, blow away the tag and try again.
-        """
-        self.updateVersion(self.app_version.scripts_tag)
+    @property
+    @chdir_to_location
+    def configured(self):
+        """Whether or not an autoinstall has been configured/installed for use."""
+        return self.application.checkConfig(self)
     @property
     def migrated(self):
         """Whether or not the autoinstalls has been migrated."""
-        return os.path.isdir(self.scripts_dir)
+        return os.path.isdir(self.wizard_dir)
+    @property
+    def wizard_dir(self):
+        """The absolute path of the Wizard directory."""
+        return os.path.join(self.location, ".wizard")
     @property
-    def scripts_dir(self):
-        """The absolute path of the ``.scripts`` directory."""
-        return os.path.join(self.location, '.scripts')
+    def backup_dir(self):
+        """The absolute path to ``.wizard/backups``."""
+        return os.path.join(self.wizard_dir, "backups")
+    # LEGACY
     @property
     def old_version_file(self):
         """
-        The absolute path of either ``.scripts-version`` (for unmigrated
-        installs) or ``.scripts/version``.
-
-        .. note::
-
-            Use of this is discouraged for migrated installs.
+        The absolute path of either ``.scripts-version``.
         """
-        if self.migrated:
-            return os.path.join(self.scripts_dir, 'old-version')
-        else:
-            return os.path.join(self.location, '.scripts-version')
+        return os.path.join(self.location, '.scripts-version')
+    @property
+    def blacklisted_file(self):
+        """The absolute path of the ``.wizard/blacklisted`` file."""
+        return os.path.join(self.wizard_dir, 'blacklisted')
+    @property
+    def pending_file(self):
+        """The absolute path of the ``.wizard/pending`` file."""
+        return os.path.join(self.wizard_dir, 'pending')
     @property
     def version_file(self):
-        """The absolute path of the ``.scripts/version`` file."""
-        return os.path.join(self.scripts_dir, 'version')
+        """The absolute path of the ``.wizard/version`` file."""
+        return os.path.join(self.wizard_dir, 'version')
+    @property
+    def dsn_file(self):
+        """The absolute path of the :file:`.wizard/dsn` override file."""
+        return os.path.join(self.wizard_dir, 'dsn')
+    @property
+    def url_file(self):
+        """The absolute path of the :file:`.wizard/url` override file."""
+        return os.path.join(self.wizard_dir, 'url')
     @property
     def application(self):
-        """The :class:`Application` of this deployment."""
+        """The :class:`app.Application` of this deployment."""
         return self.app_version.application
     @property
-    def log(self):
-        """The :class:`wizard.deploy.Log` of this deployment."""
-        if not self._log:
-            self._log = log.DeployLog.load(self)
-        return self._log
+    def old_log(self):
+        """
+        The :class:`wizard.old_log.Log` of this deployment.  This
+        is only applicable to un-migrated autoinstalls.
+        """
+        if not self._old_log:
+            self._old_log = old_log.DeployLog.load(self)
+        return self._old_log
     @property
     def version(self):
         """
@@ -167,15 +347,50 @@ class Deployment(object):
         return self.app_version.version
     @property
     def app_version(self):
-        """The :class:`ApplicationVersion` of this deployment."""
+        """The :class:`app.ApplicationVersion` of this deployment."""
         if not self._app_version:
             if os.path.isdir(os.path.join(self.location, ".git")):
-                with util.ChangeDirectory(self.location):
-                    appname, _, version = git.describe().partition('-')
-                self._app_version = ApplicationVersion.make(appname, version)
-            else:
-                self._app_version = self.log[-1].version
+                try:
+                    with util.ChangeDirectory(self.location):
+                        appname, _, version = git.describe().partition('-')
+                    self._app_version = app.ApplicationVersion.make(appname, version)
+                except shell.CallError:
+                    pass
+        if not self._app_version:
+            # LEGACY
+            try:
+                self._app_version = self.old_log[-1].version
+            except old_log.ScriptsVersionNoSuchFile:
+                pass
+        if not self._app_version:
+            appname = shell.eval("git", "config", "remote.origin.url").rpartition("/")[2].partition(".")[0]
+            self._app_version = app.ApplicationVersion.make(appname, "unknown")
         return self._app_version
+    @property
+    def dsn(self):
+        """The :class:`sqlalchemy.engine.url.URL` for this deployment."""
+        if not self._dsn:
+            self._dsn = sql.auth(self.application.dsn(self))
+        return self._dsn
+    @property
+    def url(self):
+        """The :class:`urlparse.ParseResult` for this deployment."""
+        if not self._url:
+            self.nextUrl()
+        return self._url
+    def nextUrl(self):
+        """
+        Initializes :attr:`url` with a possible URL the web application may
+        be located at.  It may be called again to switch to another possible
+        URL, usually in the event of a web access failure.
+        """
+        if not self._urlGen:
+            self._urlGen = web(self.location, self.application.url(self))
+        try:
+            self._url = self._urlGen.next() # pylint: disable-msg=E1101
+            return self._url
+        except StopIteration:
+            raise UnknownWebPath
     @staticmethod
     def parse(line):
         """
@@ -191,167 +406,148 @@ class Deployment(object):
         try:
             location, deploydir = line.split(":")
         except ValueError:
-            return Deployment(line) # lazy loaded version
+            return ProductionCopy(line) # lazy loaded version
         try:
-            return Deployment(location, version=ApplicationVersion.parse(deploydir))
+            return ProductionCopy(location, version=app.ApplicationVersion.parse(deploydir))
         except Error as e:
             e.location = location
             raise e
 
-class Application(object):
-    """Represents an application, i.e. mediawiki or phpbb."""
-    #: String name of the application
-    name = None
-    #: Dictionary of version strings to :class:`ApplicationVersion`.
-    #: See also :meth:`makeVersion`.
-    versions = None
-    #: List of files that need to be modified when parametrizing.
-    #: This is a class-wide constant, and should not normally be modified.
-    parametrized_files = []
-    def __init__(self, name):
-        self.name = name
-        self.versions = {}
-        # cache variables
-        self._extractors = {}
-        self._parametrizers = {}
-    def repository(self, srv_path):
-        """
-        Returns the Git repository that would contain this application.
-        ``srv_path`` corresponds to ``options.srv_path`` from the global baton.
-        Throws :exc:`NoRepositoryError` if the calculated path does not
-        exist.
-        """
-        repo = os.path.join(srv_path, self.name + ".git")
-        if not os.path.isdir(repo):
-            repo = os.path.join(srv_path, self.name, ".git")
-            if not os.path.isdir(repo):
-                raise NoRepositoryError(self.name)
-        return repo
-    def makeVersion(self, version):
-        """
-        Creates or retrieves the :class:`ApplicationVersion` singleton for the
-        specified version.
-        """
-        if version not in self.versions:
-            self.versions[version] = ApplicationVersion(distutils.version.LooseVersion(version), self)
-        return self.versions[version]
-    def extract(self, deployment):
-        """Extracts wizard variables from a deployment."""
-        result = {}
-        for k,extractor in self.extractors.items():
-            result[k] = extractor(deployment)
-        return result
-    def parametrize(self, deployment, dir):
-        """
-        Takes a generic source checkout at dir and parametrizes
-        it according to the values of deployment.
-        """
-        variables = deployment.extract()
-        for file in self.parametrized_files:
-            fullpath = os.path.join(dir, file)
-            f = open(fullpath, "r")
-            contents = f.read()
-            f.close()
-            for key, value in variables.items():
-                if value is None: continue
-                contents = contents.replace(key, value)
-            tmp = tempfile.NamedTemporaryFile(delete=False)
-            tmp.write(contents)
-            tmp.close()
-            os.rename(tmp.name, fullpath)
-    @property
-    def extractors(self):
-        """
-        Dictionary of variable names to extractor functions.  These functions
-        take a :class:`Deployment` as an argument and return the value of
-        the variable, or ``None`` if it could not be found.
-        See also :func:`wizard.app.filename_regex_extractor`.
-        """
-        return {}
-    @staticmethod
-    def make(name):
-        """Makes an application, but uses the correct subtype if available."""
+class ProductionCopy(Deployment):
+    """
+    Represents the production copy of a deployment.  This copy
+    is canonical, and is the only one guaranteed to be accessible
+    via web, have a database, etc.
+    """
+    @chdir_to_location
+    def upgrade(self, version, options):
+        """
+        Performs an upgrade of database schemas and other non-versioned data.
+        """
+        return self.application.upgrade(self, version, options)
+    @chdir_to_location
+    def backup(self, options):
+        """
+        Performs a backup of database schemas and other non-versioned data.
+        """
+        # There are retarded amounts of race-safety in this function,
+        # because we do NOT want to claim to have made a backup, when
+        # actually something weird happened to it.
+        if not os.path.exists(self.backup_dir):
+            try:
+                os.mkdir(self.backup_dir)
+            except OSError as e:
+                if e.errno == errno.EEXIST:
+                    pass
+                else:
+                    raise
+        tmpdir = tempfile.mkdtemp() # actually will be kept around
         try:
-            __import__("wizard.app." + name)
-            return getattr(wizard.app, name).Application(name)
-        except ImportError:
-            return Application(name)
-
-class ApplicationVersion(object):
-    """Represents an abstract notion of a version for an application, where
-    ``version`` is a :class:`distutils.version.LooseVersion` and
-    ``application`` is a :class:`Application`."""
-    #: The :class:`distutils.version.LooseVersion` of this instance.
-    version = None
-    #: The :class:`Application` of this instance.
-    application = None
-    def __init__(self, version, application):
-        self.version = version
-        self.application = application
-    @property
-    def scripts_tag(self):
+            self.application.backup(self, tmpdir, options)
+        except app.BackupFailure:
+            # the backup is bogus, don't let it show up
+            shutil.rmtree(tmpdir)
+            raise
+        backup = None
+        with util.LockDirectory(os.path.join(self.backup_dir, "lock")):
+            while 1:
+                backup = str(self.version) + "-" + datetime.datetime.today().strftime("%Y-%m-%dT%H%M%S")
+                outdir = os.path.join(self.backup_dir, backup)
+                if os.path.exists(outdir):
+                    logging.warning("Backup: A backup occurred in the last second. Trying again in a second...")
+                    time.sleep(1)
+                    continue
+                try:
+                    shutil.move(tmpdir, outdir)
+                except:
+                    # don't leave half-baked stuff lying around
+                    try:
+                        shutil.rmtree(outdir)
+                    except OSError:
+                        pass
+                    raise
+                break
+        return backup
+    @chdir_to_location
+    def restore(self, backup, options):
+        """
+        Restores a backup. Destroys state, so be careful! Also, this does
+        NOT restore the file-level backup, which is what 'wizard restore'
+        does, so you probably do NOT want to call this elsewhere unless
+        you know what you're doing (call 'wizard restore' instead).
+        """
+        return self.application.restore(self, os.path.join(self.backup_dir, backup), options)
+    @chdir_to_location
+    def remove(self, options):
+        """
+        Deletes all non-local or non-filesystem data (such as databases) that
+        this application uses.
+        """
+        self.application.remove(self, options)
+    def verifyDatabase(self):
+        """
+        Checks if the autoinstall has a properly configured database.
+        """
+        if not self.application.checkDatabase(self):
+            raise DatabaseVerificationError
+    def verifyWeb(self):
+        """
+        Checks if the autoinstall is viewable from the web.  If you do not run
+        this, there is no guarantee that the url returned by this application
+        is the correct one.
+        """
+        while True:
+            if not self.application.checkWeb(self):
+                try:
+                    self.nextUrl()
+                except UnknownWebPath:
+                    raise WebVerificationError
+            else:
+                break
+    def fetch(self, path, post=None):
         """
-        Returns the name of the Git tag for this version.
-
-        .. note::
+        Performs a HTTP request on the website.
+        """
+        return util.fetch(self.url.netloc, self.url.path, path, post) # pylint: disable-msg=E1103
 
-            Use this function only during migration, as it does
-            not account for the existence of ``-scripts2``.
+class WorkingCopy(Deployment):
+    """
+    Represents a temporary clone of a deployment that we can make
+    modifications to without fear of interfering with a production
+    deployment.  More operations are permitted on these copies.
+    """
+    @chdir_to_location
+    def parametrize(self, deployment):
         """
-        return "%s-scripts" % self.pristine_tag
-    @property
-    def pristine_tag(self):
+        Edits files in ``dir`` to replace WIZARD_* variables with literal
+        instances based on ``deployment``.  This is used for constructing
+        virtual merge bases, and as such ``deployment`` will generally not
+        equal ``self``.
         """
-        Returns the name of the Git tag for the pristine version corresponding
-        to this version.
+        return self.application.parametrize(self, deployment)
+    @chdir_to_location
+    def prepareConfig(self):
         """
-        return "%s-%s" % (self.application.name, self.version)
-    def __cmp__(x, y):
-        return cmp(x.version, y.version)
-    @staticmethod
-    def parse(value):
+        Edits files in the deployment such that any user-specific configuration
+        is replaced with generic WIZARD_* variables.
         """
-        Parses a line from the :term:`versions store` and return
-        :class:`ApplicationVersion`.
-
-        Use this only for cases when speed is of primary importance;
-        the data in version is unreliable and when possible, you should
-        prefer directly instantiating a Deployment and having it query
-        the autoinstall itself for information.
-
-        The `value` to parse will vary.  For old style installs, it
-        will look like::
-
-           /afs/athena.mit.edu/contrib/scripts/deploy/APP-x.y.z
-
-        For new style installs, it will look like::
-
-           APP-x.y.z-scripts
+        return self.application.prepareConfig(self)
+    @chdir_to_location
+    def resolveConflicts(self):
         """
-        name = value.split("/")[-1]
-        try:
-            if name.find("-") != -1:
-                app, _, version = name.partition("-")
-            else:
-                # kind of poor, maybe should error.  Generally this
-                # will actually result in a not found error
-                app = name
-                version = "trunk"
-        except ValueError:
-            raise DeploymentParseError(deploydir)
-        return ApplicationVersion.make(app, version)
-    @staticmethod
-    def make(app, version):
+        Resolves conflicted files in this working copy.  Returns whether or
+        not all conflicted files were resolved or not.  Fully resolved
+        files are added to the index, but no commit is made.
         """
-        Makes/retrieves a singleton :class:`ApplicationVersion` from
-        a``app`` and ``version`` string.
+        return self.application.resolveConflicts(self)
+    @chdir_to_location
+    def prepareMerge(self):
         """
-        try:
-            # defer to the application for version creation to enforce
-            # singletons
-            return applications()[app].makeVersion(version)
-        except KeyError:
-            raise NoSuchApplication(app)
+        Performs various edits to files in the current working directory in
+        order to make a merge go more smoothly.  This is usually
+        used to fix botched line-endings.
+        """
+        return self.application.prepareMerge(self)
 
 ## -- Exceptions --
 
@@ -359,58 +555,183 @@ class Error(wizard.Error):
     """Base error class for this module"""
     pass
 
-class NoSuchApplication(Error):
+# LEGACY
+class NotMigratedError(Error):
     """
-    You attempted to reference a :class:`Application` named
-    ``app``, which is not recognized by Wizard.
+    The deployment contains a .scripts-version file, but no .git
+    or .wizard directory.
     """
-    #: The name of the application that does not exist.
-    app = None
-    #: The location of the autoinstall that threw this variable.
-    #: This should be set by error handling code when it is availble.
-    location = None
-    def __init__(self, app):
-        self.app = app
+    #: Directory of deployment
+    dir = None
+    def __init__(self, dir):
+        self.dir = dir
+    def __str__(self):
+        return """This installation was not migrated"""
+
+class AlreadyVersionedError(Error):
+    """The deployment contained a .git directory but no .wizard directory."""
+    #: Directory of deployment
+    dir = None
+    def __init__(self, dir):
+        self.dir = dir
+    def __str__(self):
+        return """
+
+ERROR: Directory contains a .git directory, but not
+a .wizard directory.  If this is not a corrupt
+migration, this means that the user was versioning their
+install using Git."""
+
+class NotConfiguredError(Error):
+    """The install was missing essential configuration."""
+    #: Directory of unconfigured install
+    dir = None
+    def __init__(self, dir):
+        self.dir = dir
+    def __str__(self):
+        return """
 
-class DeploymentParseError(Error):
-    """
-    Could not parse ``value`` from :term:`versions store`.
-    """
-    #: The value that failed to parse.
-    value = None
-    #: The location of the autoinstall that threw this variable.
-    #: This should be set by error handling code when it is available.
-    location = None
-    def __init__(self, value):
-        self.value = value
+ERROR: The install was well-formed, but not configured
+(essential configuration files were not found.)"""
 
-class NoRepositoryError(Error):
-    """
-    :class:`Application` does not appear to have a Git repository
-    in the normal location.
-    """
-    #: The name of the application that does not have a Git repository.
-    app = None
-    def __init__(self, app):
-        self.app = app
+class CorruptedAutoinstallError(Error):
+    """The install was missing a .git directory, but had a .wizard directory."""
+    #: Directory of the corrupted install
+    dir = None
+    def __init__(self, dir):
+        self.dir = dir
+    def __str__(self):
+        return """
+
+ERROR: Directory contains a .wizard directory,
+but not a .git directory."""
+
+class NotAutoinstallError(Error):
+    """Application is not an autoinstall."""
+    #: Directory of the not autoinstall
+    dir = None
+    def __init__(self, dir):
+        self.dir = dir
+    def __str__(self):
+        return """
+
+ERROR: The directory
+
+    %s
+
+does not appear to be an autoinstall.  If you are in a
+subdirectory of an autoinstall, you need to use the root
+directory for the autoinstall.""" % self.dir
+
+class NoTagError(Error):
+    """Deployment has a tag that does not have an equivalent in upstream repository."""
+    #: Missing tag
+    tag = None
+    def __init__(self, tag):
+        self.tag = tag
+    def __str__(self):
+        return """
+
+ERROR: Could not find tag %s in repository.""" % self.tag
+
+class NoLocalTagError(Error):
+    """Could not find tag in local repository."""
+    #: Missing tag
+    tag = None
+    def __init__(self, tag):
+        self.tag = tag
+    def __str__(self):
+        return """
+
+ERROR: Could not find tag %s in local repository.""" % self.tag
+
+class InconsistentPristineTagError(Error):
+    """Pristine tag commit ID does not match upstream pristine tag commit ID."""
+    #: Inconsistent tag
+    tag = None
+    def __init__(self, tag):
+        self.tag = tag
+    def __str__(self):
+        return """
+
+ERROR: Local pristine tag %s did not match repository's.  This
+probably means an upstream rebase occured.""" % self.tag
+
+class InconsistentWizardTagError(Error):
+    """Wizard tag commit ID does not match upstream wizard tag commit ID."""
+    #: Inconsistent tag
+    tag = None
+    def __init__(self, tag):
+        self.tag = tag
+    def __str__(self):
+        return """
+
+ERROR: Local wizard tag %s did not match repository's.  This
+probably means an upstream rebase occurred.  Try
+'git fetch --tags && wizard remaster'.""" % self.tag
+
+class HeadNotDescendantError(Error):
+    """HEAD is not connected to tag."""
+    #: Tag that HEAD should have been descendant of.
+    tag = None
+    def __init__(self, tag):
+        self.tag = tag
+    def __str__(self):
+        return """
+
+ERROR: HEAD is not a descendant of %s.  This probably
+means that an upstream rebase occurred, and new tags were
+pulled, but local user commits were never rebased.  Try
+running 'wizard remaster'.""" % self.tag
+
+class VersionDetectionError(Error):
+    """Could not detect real version of application."""
+    def __str__(self):
+        return """
+
+ERROR: Could not detect the real version of the application."""
+
+class VersionMismatchError(Error):
+    """Git version of application does not match detected version."""
+    #: Detected version
+    real_version = None
+    #: Version from Git
+    git_version = None
+    def __init__(self, real_version, git_version):
+        self.real_version = real_version
+        self.git_version = git_version
+    def __str__(self):
+        return """
+
+ERROR: The detected version %s did not match the Git
+version %s.""" % (self.real_version, self.git_version)
+
+class WebVerificationError(Error):
+    """Could not access the application on the web"""
+    def __str__(self):
+        return """
+
+ERROR: We were not able to access the application on the
+web.  This may indicate that the website is behind
+authentication on the htaccess level.  You can find
+the contents of the page from the debug backtraces."""
+
+class DatabaseVerificationError(Error):
+    """Could not access the database"""
+    def __str__(self):
+        return """
+
+ERROR: We were not able to access the database for
+this application; this probably means that your database
+configuration is misconfigured."""
+
+class UnknownWebPath(Error):
+    """Could not determine application's web path."""
     def __str__(self):
-        return """Could not find Git repository for '%s'.  If you would like to use a local version, try specifying --srv-path or WIZARD_SRV_PATH.""" % self.app
-
-# If you want, you can wrap this up into a registry and access things
-# through that, but it's not really necessary
-
-_application_list = [
-    "mediawiki", "wordpress", "joomla", "e107", "gallery2",
-    "phpBB", "advancedbook", "phpical", "trac", "turbogears", "django",
-    # these are technically deprecated
-    "advancedpoll", "gallery",
-]
-_applications = None
-
-def applications():
-    """Hash table for looking up string application name to instance"""
-    global _applications
-    if not _applications:
-        _applications = dict([(n,Application.make(n)) for n in _application_list ])
-    return _applications
+        return """
 
+ERROR: We were not able to determine what the application's
+host and path were in order to perform a web request
+on the application.  You can specify this manually using
+the WIZARD_WEB_HOST and WIZARD_WEB_PATH environment
+variables."""