db: Create a utility to get credentials from dbconfig

Create helper function that uses Augeas Shellvars to parse dbconfig-common
files.

Signed-off-by: Frederico Gomes fredericojfgomes@gmail.com
[sunil: Fix quotes not getting removed from values]
[sunil: Add test case]
Signed-off-by: Sunil Mohan Adapa <sunil@medhas.org>
Reviewed-by: Sunil Mohan Adapa <sunil@medhas.org>

plinth/db/dbconfig.py

@@ -0,0 +1,40 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
+"""Utilities for parsing dbconfig-common files with Augeas."""
+
+import pathlib
+
+import augeas
+
+
+def get_credentials(dbconfig_path: str) -> dict[str, str]:
+    """Parse dbconfig-common file with Augeas Shellvars lens."""
+    if not pathlib.Path(dbconfig_path).is_file():
+        raise FileNotFoundError(f'DB config not found: {dbconfig_path}')
+
+    aug = _load_augeas(dbconfig_path)
+
+    required = ['dbc_dbuser', 'dbc_dbpass', 'dbc_dbname']
+    credentials = {}
+    for key in required + ['dbc_dbserver']:
+        credentials[key] = aug.get(key).strip('\'"')
+
+    if not all(credentials.get(key) for key in required):
+        raise ValueError('Missing required dbconfig-common credentials')
+
+    return {
+        'user': credentials['dbc_dbuser'],
+        'password': credentials['dbc_dbpass'],
+        'database': credentials['dbc_dbname'],
+        'host': credentials['dbc_dbserver'] or 'localhost'
+    }
+
+
+def _load_augeas(config_path: str):
+    """Initialize Augeas."""
+    aug = augeas.Augeas(flags=augeas.Augeas.NO_LOAD +
+                        augeas.Augeas.NO_MODL_AUTOLOAD)
+    pathstr = str(config_path)
+    aug.transform('Shellvars', pathstr)
+    aug.set('/augeas/context', f'/files{pathstr}')
+    aug.load()
+    return aug

plinth/tests/test_db.py

@@ -6,6 +6,7 @@ import threading
 import time
 
 from .. import db
+from ..db import dbconfig
 
 
 def test_db_lock_no_wait():
@@ -66,3 +67,22 @@ def test_db_lock_release():
     end_time = time.time()
     assert return_value
     assert end_time - start_time <= 0.23
+
+
+def test_dbconfig_get_credentials(tmp_path):
+    """Test that parsing a dbconfig-common file works."""
+    file_path = tmp_path / 'test.conf'
+    configuration = '''
+dbc_dbserver='localhost'
+dbc_dbname='miniflux'
+dbc_dbuser='miniflux'
+dbc_dbpass='gCcNyWjyPjDH'
+'''
+    file_path.write_text(configuration)
+    credentials = dbconfig.get_credentials(file_path)
+    assert credentials == {
+        'host': 'localhost',
+        'database': 'miniflux',
+        'user': 'miniflux',
+        'password': 'gCcNyWjyPjDH',
+    }