configquery: T3402: add library for querying config values from op mode

A small library that allows querying existence or value(s) of config
settings from op mode, and execution of arbitrary op mode commands.

1 files changed, 90 insertions, 0 deletions

diff --git a/python/vyos/configquery.py b/python/vyos/configquery.py
new file mode 100644
index 000000000..ed7346f1f
--- /dev/null
+++ b/python/vyos/configquery.py
@@ -0,0 +1,90 @@
+# Copyright 2021 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/>.
+
+'''
+A small library that allows querying existence or value(s) of config
+settings from op mode, and execution of arbitrary op mode commands.
+'''
+
+from subprocess import STDOUT
+from vyos.util import popen
+
+
+class ConfigQueryError(Exception):
+    pass
+
+class GenericConfigQuery:
+    def __init__(self):
+        pass
+
+    def exists(self, path: list):
+        raise NotImplementedError
+
+    def value(self, path: list):
+        raise NotImplementedError
+
+    def values(self, path: list):
+        raise NotImplementedError
+
+class GenericOpRun:
+    def __init__(self):
+        pass
+
+    def run(self, path: list, **kwargs):
+        raise NotImplementedError
+
+class CliShellApiConfigQuery(GenericConfigQuery):
+    def __init__(self):
+        super().__init__()
+
+    def exists(self, path: list):
+        cmd = ' '.join(path)
+        (_, err) = popen(f'cli-shell-api existsActive {cmd}')
+        if err:
+            return False
+        return True
+
+    def value(self, path: list):
+        cmd = ' '.join(path)
+        (out, err) = popen(f'cli-shell-api returnActiveValue {cmd}')
+        if err:
+            raise ConfigQueryError('No value for given path')
+        return out
+
+    def values(self, path: list):
+        cmd = ' '.join(path)
+        (out, err) = popen(f'cli-shell-api returnActiveValues {cmd}')
+        if err:
+            raise ConfigQueryError('No values for given path')
+        return out
+
+class VbashOpRun(GenericOpRun):
+    def __init__(self):
+        super().__init__()
+
+    def run(self, path: list, **kwargs):
+        cmd = ' '.join(path)
+        (out, err) = popen(f'.  /opt/vyatta/share/vyatta-op/functions/interpreter/vyatta-op-run; _vyatta_op_run {cmd}', stderr=STDOUT, **kwargs)
+        if err:
+            raise ConfigQueryError(out)
+        return out
+
+def query_context(config_query_class=CliShellApiConfigQuery,
+                  op_run_class=VbashOpRun):
+    query = config_query_class()
+    run = op_run_class()
+    return query, run
+
+