Fixed #23658 -- Provided the password to PostgreSQL dbshell command

The password from settings.py is written in a temporary .pgpass file
file whose name is given to psql using the PGPASSFILE environment
variable.

django/db/backends/postgresql_psycopg2/client.py

+import os
 import subprocess
 
+from django.core.files.temp import NamedTemporaryFile
 from django.db.backends.base.client import BaseDatabaseClient
+from django.utils.six import print_
+
+
+def _escape_pgpass(txt):
+    """
+    Escape a fragment of a PostgreSQL .pgpass file.
+    """
+    return txt.replace('\\', '\\\\').replace(':', '\\:')
 
 
 class DatabaseClient(BaseDatabaseClient):
     executable_name = 'psql'
 
+    @classmethod
+    def runshell_db(cls, settings_dict):
+        args = [cls.executable_name]
+
+        host = settings_dict.get('HOST', '')
+        port = settings_dict.get('PORT', '')
+        name = settings_dict.get('NAME', '')
+        user = settings_dict.get('USER', '')
+        passwd = settings_dict.get('PASSWORD', '')
+
+        if user:
+            args += ['-U', user]
+        if host:
+            args += ['-h', host]
+        if port:
+            args += ['-p', str(port)]
+        args += [name]
+
+        temp_pgpass = None
+        try:
+            if passwd:
+                # Create temporary .pgpass file.
+                temp_pgpass = NamedTemporaryFile(mode='w+')
+                try:
+                    print_(
+                        _escape_pgpass(host) or '*',
+                        str(port) or '*',
+                        _escape_pgpass(name) or '*',
+                        _escape_pgpass(user) or '*',
+                        _escape_pgpass(passwd),
+                        file=temp_pgpass,
+                        sep=':',
+                        flush=True,
+                    )
+                    os.environ['PGPASSFILE'] = temp_pgpass.name
+                except UnicodeEncodeError:
+                    # If the current locale can't encode the data, we let
+                    # the user input the password manually.
+                    pass
+            subprocess.call(args)
+        finally:
+            if temp_pgpass:
+                temp_pgpass.close()
+                if 'PGPASSFILE' in os.environ:  # unit tests need cleanup
+                    del os.environ['PGPASSFILE']
+
     def runshell(self):
-        settings_dict = self.connection.settings_dict
-        args = [self.executable_name]
-        if settings_dict['USER']:
-            args += ["-U", settings_dict['USER']]
-        if settings_dict['HOST']:
-            args.extend(["-h", settings_dict['HOST']])
-        if settings_dict['PORT']:
-            args.extend(["-p", str(settings_dict['PORT'])])
-        args += [settings_dict['NAME']]
-        subprocess.call(args)
+        DatabaseClient.runshell_db(self.connection.settings_dict)

docs/releases/1.9.txt

@@ -350,6 +350,10 @@ Management Commands
 * The :djadmin:`startapp` command creates an ``apps.py`` file and adds
   ``default_app_config`` in ``__init__.py``.
 
+* When using the PostgreSQL backend, the :djadmin:`dbshell` command can connect
+  to the database using the password from your settings file (instead of
+  requiring it to be manually entered).
+
 Models
 ^^^^^^
 

tests/dbshell/test_postgresql_psycopg2.py

+# -*- coding: utf8 -*-
+from __future__ import unicode_literals
+
+import locale
+import os
+
+from django.db.backends.postgresql_psycopg2.client import DatabaseClient
+from django.test import SimpleTestCase, mock
+from django.utils import six
+from django.utils.encoding import force_bytes, force_str
+
+
+class PostgreSqlDbshellCommandTestCase(SimpleTestCase):
+
+    def _run_it(self, dbinfo):
+        """
+        That function invokes the runshell command, while mocking
+        subprocess.call. It returns a 2-tuple with:
+        - The command line list
+        - The binary content of file pointed by environment PGPASSFILE, or
+          None.
+        """
+        def _mock_subprocess_call(*args):
+            self.subprocess_args = list(*args)
+            if 'PGPASSFILE' in os.environ:
+                self.pgpass = open(os.environ['PGPASSFILE'], 'rb').read()
+            else:
+                self.pgpass = None
+            return 0
+        self.subprocess_args = None
+        self.pgpass = None
+        with mock.patch('subprocess.call', new=_mock_subprocess_call):
+            DatabaseClient.runshell_db(dbinfo)
+        return self.subprocess_args, self.pgpass
+
+    def test_basic(self):
+        self.assertEqual(
+            self._run_it({
+                'NAME': 'dbname',
+                'USER': 'someuser',
+                'PASSWORD': 'somepassword',
+                'HOST': 'somehost',
+                'PORT': 444,
+            }), (
+                ['psql', '-U', 'someuser', '-h', 'somehost', '-p', '444', 'dbname'],
+                b'somehost:444:dbname:someuser:somepassword\n',
+            )
+        )
+
+    def test_nopass(self):
+        self.assertEqual(
+            self._run_it({
+                'NAME': 'dbname',
+                'USER': 'someuser',
+                'HOST': 'somehost',
+                'PORT': 444,
+            }), (
+                ['psql', '-U', 'someuser', '-h', 'somehost', '-p', '444', 'dbname'],
+                None,
+            )
+        )
+
+    def test_column(self):
+        self.assertEqual(
+            self._run_it({
+                'NAME': 'dbname',
+                'USER': 'some:user',
+                'PASSWORD': 'some:password',
+                'HOST': '::1',
+                'PORT': 444,
+            }), (
+                ['psql', '-U', 'some:user', '-h', '::1', '-p', '444', 'dbname'],
+                b'\\:\\:1:444:dbname:some\\:user:some\\:password\n',
+            )
+        )
+
+    def test_escape_characters(self):
+        self.assertEqual(
+            self._run_it({
+                'NAME': 'dbname',
+                'USER': 'some\\user',
+                'PASSWORD': 'some\\password',
+                'HOST': 'somehost',
+                'PORT': 444,
+            }), (
+                ['psql', '-U', 'some\\user', '-h', 'somehost', '-p', '444', 'dbname'],
+                b'somehost:444:dbname:some\\\\user:some\\\\password\n',
+            )
+        )
+
+    def test_accent(self):
+        # The pgpass temporary file needs to be encoded using the system locale.
+        encoding = locale.getpreferredencoding()
+        username = 'rôle'
+        password = 'sésame'
+        try:
+            username_str = force_str(username, encoding)
+            password_str = force_str(password, encoding)
+            pgpass_bytes = force_bytes(
+                'somehost:444:dbname:%s:%s\n' % (username, password),
+                encoding=encoding,
+            )
+        except UnicodeEncodeError:
+            if six.PY2:
+                self.skipTest("Your locale can't run this test.")
+        self.assertEqual(
+            self._run_it({
+                'NAME': 'dbname',
+                'USER': username_str,
+                'PASSWORD': password_str,
+                'HOST': 'somehost',
+                'PORT': 444,
+            }), (
+                ['psql', '-U', username_str, '-h', 'somehost', '-p', '444', 'dbname'],
+                pgpass_bytes,
+            )
+        )