Merge pull request #499 from jestabro/config_source

T2707: allow alternative initialization data for config

config: T2707: use ConfigSource and refactor Config methods
load-config: subclass ConfigSourceSession instead of Config
http-api: remove unneeded check for VyOSError
config: T2707: add ConfigSource classes for alternative init data

1 files changed, 318 insertions, 0 deletions

diff --git a/python/vyos/configsource.py b/python/vyos/configsource.py
new file mode 100644
index 000000000..50222e385
--- /dev/null
+++ b/python/vyos/configsource.py
@@ -0,0 +1,318 @@
+
+# Copyright 2020 VyOS maintainers and contributors <maintainers@vyos.io>
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2.1 of the License, or (at your option) any later version.
+#
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with this library.  If not, see <http://www.gnu.org/licenses/>.
+
+import os
+import re
+import subprocess
+
+from vyos.configtree import ConfigTree
+
+class VyOSError(Exception):
+    """
+    Raised on config access errors.
+    """
+    pass
+
+class ConfigSourceError(Exception):
+    '''
+    Raised on error in ConfigSource subclass init.
+    '''
+    pass
+
+class ConfigSource:
+    def __init__(self):
+        self._running_config: ConfigTree = None
+        self._session_config: ConfigTree = None
+
+    def get_configtree_tuple(self):
+        return self._running_config, self._session_config
+
+    def session_changed(self):
+        """
+        Returns:
+            True if the config session has uncommited changes, False otherwise.
+        """
+        raise NotImplementedError(f"function not available for {type(self)}")
+
+    def in_session(self):
+        """
+        Returns:
+            True if called from a configuration session, False otherwise.
+        """
+        raise NotImplementedError(f"function not available for {type(self)}")
+
+    def show_config(self, path=[], default=None, effective=False):
+        """
+        Args:
+            path (str|list): Configuration tree path, or empty
+            default (str): Default value to return
+
+        Returns:
+            str: working configuration
+        """
+        raise NotImplementedError(f"function not available for {type(self)}")
+
+    def is_multi(self, path):
+        """
+        Args:
+            path (str): Configuration tree path
+
+        Returns:
+            True if a node can have multiple values, False otherwise.
+
+        Note:
+            It also returns False if node doesn't exist.
+        """
+        raise NotImplementedError(f"function not available for {type(self)}")
+
+    def is_tag(self, path):
+        """
+         Args:
+            path (str): Configuration tree path
+
+        Returns:
+            True if a node is a tag node, False otherwise.
+
+        Note:
+            It also returns False if node doesn't exist.
+        """
+        raise NotImplementedError(f"function not available for {type(self)}")
+
+    def is_leaf(self, path):
+        """
+         Args:
+            path (str): Configuration tree path
+
+        Returns:
+            True if a node is a leaf node, False otherwise.
+
+        Note:
+            It also returns False if node doesn't exist.
+        """
+        raise NotImplementedError(f"function not available for {type(self)}")
+
+class ConfigSourceSession(ConfigSource):
+    def __init__(self, session_env=None):
+        super().__init__()
+        self._cli_shell_api = "/bin/cli-shell-api"
+        self._level = []
+        if session_env:
+            self.__session_env = session_env
+        else:
+            self.__session_env = None
+
+        # Running config can be obtained either from op or conf mode, it always succeeds
+        # once the config system is initialized during boot;
+        # before initialization, set to empty string
+        if os.path.isfile('/tmp/vyos-config-status'):
+            try:
+                running_config_text = self._run([self._cli_shell_api, '--show-active-only', '--show-show-defaults', '--show-ignore-edit', 'showConfig'])
+            except VyOSError:
+                running_config_text = ''
+        else:
+            running_config_text = ''
+
+        # Session config ("active") only exists in conf mode.
+        # In op mode, we'll just use the same running config for both active and session configs.
+        if self.in_session():
+            try:
+                session_config_text = self._run([self._cli_shell_api, '--show-working-only', '--show-show-defaults', '--show-ignore-edit', 'showConfig'])
+            except VyOSError:
+                session_config_text = ''
+        else:
+            session_config_text = running_config_text
+
+        if running_config_text:
+            self._running_config = ConfigTree(running_config_text)
+        else:
+            self._running_config = None
+
+        if session_config_text:
+            self._session_config = ConfigTree(session_config_text)
+        else:
+            self._session_config = None
+
+    def _make_command(self, op, path):
+        args = path.split()
+        cmd = [self._cli_shell_api, op] + args
+        return cmd
+
+    def _run(self, cmd):
+        if self.__session_env:
+            p = subprocess.Popen(cmd, stdout=subprocess.PIPE, env=self.__session_env)
+        else:
+            p = subprocess.Popen(cmd, stdout=subprocess.PIPE)
+        out = p.stdout.read()
+        p.wait()
+        p.communicate()
+        if p.returncode != 0:
+            raise VyOSError()
+        else:
+            return out.decode('ascii')
+
+    def set_level(self, path):
+        """
+        Set the *edit level*, that is, a relative config tree path.
+        Once set, all operations will be relative to this path,
+        for example, after ``set_level("system")``, calling
+        ``exists("name-server")`` is equivalent to calling
+        ``exists("system name-server"`` without ``set_level``.
+
+        Args:
+            path (str|list): relative config path
+        """
+        # Make sure there's always a space between default path (level)
+        # and path supplied as method argument
+        # XXX: for small strings in-place concatenation is not a problem
+        if isinstance(path, str):
+            if path:
+                self._level = re.split(r'\s+', path)
+            else:
+                self._level = []
+        elif isinstance(path, list):
+            self._level = path.copy()
+        else:
+            raise TypeError("Level path must be either a whitespace-separated string or a list")
+
+    def session_changed(self):
+        """
+        Returns:
+            True if the config session has uncommited changes, False otherwise.
+        """
+        try:
+            self._run(self._make_command('sessionChanged', ''))
+            return True
+        except VyOSError:
+            return False
+
+    def in_session(self):
+        """
+        Returns:
+            True if called from a configuration session, False otherwise.
+        """
+        try:
+            self._run(self._make_command('inSession', ''))
+            return True
+        except VyOSError:
+            return False
+
+    def show_config(self, path=[], default=None, effective=False):
+        """
+        Args:
+            path (str|list): Configuration tree path, or empty
+            default (str): Default value to return
+
+        Returns:
+            str: working configuration
+        """
+
+        # show_config should be independent of CLI edit level.
+        # Set the CLI edit environment to the top level, and
+        # restore original on exit.
+        save_env = self.__session_env
+
+        env_str = self._run(self._make_command('getEditResetEnv', ''))
+        env_list = re.findall(r'([A-Z_]+)=\'([^;\s]+)\'', env_str)
+        root_env = os.environ
+        for k, v in env_list:
+            root_env[k] = v
+
+        self.__session_env = root_env
+
+        # FIXUP: by default, showConfig will give you a diff
+        # if there are uncommitted changes.
+        # The config parser obviously cannot work with diffs,
+        # so we need to supress diff production using appropriate
+        # options for getting either running (active)
+        # or proposed (working) config.
+        if effective:
+            path = ['--show-active-only'] + path
+        else:
+            path = ['--show-working-only'] + path
+
+        if isinstance(path, list):
+            path = " ".join(path)
+        try:
+            out = self._run(self._make_command('showConfig', path))
+            self.__session_env = save_env
+            return out
+        except VyOSError:
+            self.__session_env = save_env
+            return(default)
+
+    def is_multi(self, path):
+        """
+        Args:
+            path (str): Configuration tree path
+
+        Returns:
+            True if a node can have multiple values, False otherwise.
+
+        Note:
+            It also returns False if node doesn't exist.
+        """
+        try:
+            path = " ".join(self._level) + " " + path
+            self._run(self._make_command('isMulti', path))
+            return True
+        except VyOSError:
+            return False
+
+    def is_tag(self, path):
+        """
+         Args:
+            path (str): Configuration tree path
+
+        Returns:
+            True if a node is a tag node, False otherwise.
+
+        Note:
+            It also returns False if node doesn't exist.
+        """
+        try:
+            path = " ".join(self._level) + " " + path
+            self._run(self._make_command('isTag', path))
+            return True
+        except VyOSError:
+            return False
+
+    def is_leaf(self, path):
+        """
+         Args:
+            path (str): Configuration tree path
+
+        Returns:
+            True if a node is a leaf node, False otherwise.
+
+        Note:
+            It also returns False if node doesn't exist.
+        """
+        try:
+            path = " ".join(self._level) + " " + path
+            self._run(self._make_command('isLeaf', path))
+            return True
+        except VyOSError:
+            return False
+
+class ConfigSourceString(ConfigSource):
+    def __init__(self, running_config_text=None, session_config_text=None):
+        super().__init__()
+
+        try:
+            self._running_config = ConfigTree(running_config_text) if running_config_text else None
+            self._session_config = ConfigTree(session_config_text) if session_config_text else None
+        except ValueError:
+            raise ConfigSourceError(f"Init error in {type(self)}")