miniflux, ttrss: Factor out duplicated postgres utility methods

Tests:

- Run functional tests on miniflux app.
- Run backup and restore on ttrss app manually and notice that data is restored
and there are no errors.

Signed-off-by: Sunil Mohan Adapa <sunil@medhas.org>
Reviewed-by: Joseph Nuthalapati <njoseph@riseup.net>

plinth/db.py

@@ -3,6 +3,8 @@
 Common utilities to help with handling a database.
 """
 
+import pathlib
+import subprocess
 import threading
 from typing import ClassVar
 
@@ -83,3 +85,51 @@ class DBLock:
 # most of the significant cases where we have seen database lock issues.
 
 lock = DBLock()
+
+
+#
+# PostgreSQL utilites
+#
+def _run_as_postgres(command, stdin=None, stdout=None):
+    """Run a command as postgres user."""
+    command = ['sudo', '--user', 'postgres'] + command
+    return subprocess.run(command, stdin=stdin, stdout=stdout, check=True)
+
+
+def postgres_dump_database(backup_file: str, database_name: str,
+                           database_user: str):
+    """Dump PostgreSQL database to a file.
+
+    Overwrites file if it exists. Uses pg_dump utility from postgres package
+    (needs to be installed).
+    """
+    backup_path = pathlib.Path(backup_file)
+    backup_path.parent.mkdir(parents=True, exist_ok=True)
+    with open(backup_path, 'w', encoding='utf-8') as file_handle:
+        process = _run_as_postgres(['pg_dumpall', '--roles-only'],
+                                   stdout=subprocess.PIPE)
+        file_handle.write(f'DROP ROLE IF EXISTS {database_user};\n')
+        for line in process.stdout.decode().splitlines():
+            if database_user in line:
+                file_handle.write(line + '\n')
+
+    with open(backup_path, 'a', encoding='utf-8') as file_handle:
+        _run_as_postgres(
+            ['pg_dump', '--create', '--clean', '--if-exists', database_name],
+            stdout=file_handle)
+
+
+def postgres_restore_database(backup_file: str, database_name):
+    """Restore PostgreSQL database from a file.
+
+    Drops database and recreates it. Uses pg_dump utility from postgres package
+    (needs to be installed).
+    """
+    # This is needed for old backups only. New backups include 'DROP DATABASE
+    # IF EXISTS' and 'CREATE DATABASE' statements.
+    _run_as_postgres(['dropdb', database_name])
+    _run_as_postgres(['createdb', database_name])
+
+    with open(backup_file, 'r', encoding='utf-8') as file_handle:
+        _run_as_postgres(['psql', '--dbname', database_name],
+                         stdin=file_handle)

plinth/modules/miniflux/privileged.py

@@ -4,13 +4,12 @@
 import json
 import os
 import pathlib
-import subprocess
 from typing import Tuple
 from urllib.parse import urlparse
 
 import pexpect
 
-from plinth import action_utils
+from plinth import action_utils, db
 from plinth.actions import privileged
 from plinth.utils import is_non_empty_file
 
@@ -124,44 +123,16 @@ def _get_database_config():
     }
 
 
-# The following 3 methods are duplicated in tt-rss/privileged.py
-
-
-def _run_as_postgres(command, stdin=None, stdout=None):
-    """Run a command as postgres user."""
-    command = ['sudo', '--user', 'postgres'] + command
-    return subprocess.run(command, stdin=stdin, stdout=stdout, check=True)
-
-
 @privileged
 def dump_database():
     """Dump database to file."""
     config = _get_database_config()
-    os.makedirs(os.path.dirname(DB_BACKUP_FILE), exist_ok=True)
-    with open(DB_BACKUP_FILE, 'w', encoding='utf-8') as db_backup_file:
-        process = _run_as_postgres(['pg_dumpall', '--roles-only'],
-                                   stdout=subprocess.PIPE)
-        db_backup_file.write(f'DROP ROLE IF EXISTS {config["user"]};\n')
-        for line in process.stdout.decode().splitlines():
-            if config['user'] in line:
-                db_backup_file.write(line + '\n')
-
-    with open(DB_BACKUP_FILE, 'a', encoding='utf-8') as db_backup_file:
-        _run_as_postgres([
-            'pg_dump', '--create', '--clean', '--if-exists', config['database']
-        ], stdout=db_backup_file)
+    db.postgres_dump_database(DB_BACKUP_FILE, config['database'],
+                              config['user'])
 
 
 @privileged
 def restore_database():
     """Restore database from file."""
     config = _get_database_config()
-
-    # This is needed for old backups only. New backups include 'DROP DATABASE
-    # IF EXISTS' and 'CREATE DATABASE' statements.
-    _run_as_postgres(['dropdb', config['database']])
-    _run_as_postgres(['createdb', config['database']])
-
-    with open(DB_BACKUP_FILE, 'r', encoding='utf-8') as db_restore_file:
-        _run_as_postgres(['psql', '--dbname', config['database']],
-                         stdin=db_restore_file)
+    db.postgres_restore_database(DB_BACKUP_FILE, config['database'])

plinth/modules/ttrss/privileged.py

@@ -1,12 +1,9 @@
 # SPDX-License-Identifier: AGPL-3.0-or-later
 """Configure Tiny Tiny RSS."""
 
-import os
-import subprocess
-
 import augeas
 
-from plinth import action_utils
+from plinth import action_utils, db
 from plinth.actions import privileged
 
 CONFIG_FILE = '/etc/tt-rss/config.php'
@@ -124,40 +121,15 @@ def enable_api_access():
 def dump_database():
     """Dump database to file."""
     config = _get_database_config()
-    os.makedirs(os.path.dirname(DB_BACKUP_FILE), exist_ok=True)
-    with open(DB_BACKUP_FILE, 'w', encoding='utf-8') as db_backup_file:
-        process = _run_as_postgres(['pg_dumpall', '--roles-only'],
-                                   stdout=subprocess.PIPE)
-        db_backup_file.write(f'DROP ROLE IF EXISTS {config["user"]};\n')
-        for line in process.stdout.decode().splitlines():
-            if config['user'] in line:
-                db_backup_file.write(line + '\n')
-
-    with open(DB_BACKUP_FILE, 'a', encoding='utf-8') as db_backup_file:
-        _run_as_postgres([
-            'pg_dump', '--create', '--clean', '--if-exists', config['database']
-        ], stdout=db_backup_file)
+    db.postgres_dump_database(DB_BACKUP_FILE, config['database'],
+                              config['user'])
 
 
 @privileged
 def restore_database():
     """Restore database from file."""
     config = _get_database_config()
-
-    # This is needed for old backups only. New backups include 'DROP DATABASE
-    # IF EXISTS' and 'CREATE DATABASE' statements.
-    _run_as_postgres(['dropdb', config['database']])
-    _run_as_postgres(['createdb', config['database']])
-
-    with open(DB_BACKUP_FILE, 'r', encoding='utf-8') as db_restore_file:
-        _run_as_postgres(['psql', '--dbname', config['database']],
-                         stdin=db_restore_file)
-
-
-def _run_as_postgres(command, stdin=None, stdout=None):
-    """Run a command as postgres user."""
-    command = ['sudo', '--user', 'postgres'] + command
-    return subprocess.run(command, stdin=stdin, stdout=stdout, check=True)
+    db.postgres_restore_database(DB_BACKUP_FILE, config['database'])
 
 
 def load_augeas():