Added a new flag to ignore unsuccessful bind (patroni#3138)

Author: sahilnap06

docs/patroni_configuration.rst

@@ -238,7 +238,7 @@ Validate Patroni configuration
 
 .. code:: text
 
-   patroni --validate-config [configfile]
+   patroni --validate-config [configfile] [--ignore-listen-port | -i]
 
 Description
 """""""""""
@@ -250,3 +250,6 @@ Parameters
 
 ``configfile``
     Full path to the configuration file to check. If not given or file does not exist, will try to read from the ``PATRONI_CONFIG_VARIABLE`` environment variable or, if not set, from the :ref:`Patroni environment variables <environment>`.
+
+``--ignore-listen-port | -i``
+    Optional flag to ignore bind failures for ``listen`` ports that are already in use when validating the ``configfile``.

patroni/__main__.py

@@ -241,6 +241,8 @@ def process_arguments() -> Namespace:
       * ``--validate-config`` -- used to validate the Patroni configuration file
       * ``--generate-config`` -- used to generate Patroni configuration from a running PostgreSQL instance
       * ``--generate-sample-config`` -- used to generate a sample Patroni configuration
+      * ``--ignore-listen-port`` | ``-i`` -- used to ignore ``listen`` ports already in use.
+          Can be used only with ``--validate-config``
 
     .. note::
         If running with ``--generate-config``, ``--generate-sample-config`` or ``--validate-flag`` will exit
@@ -259,6 +261,9 @@ def process_arguments() -> Namespace:
                        help='Generate a Patroni yaml configuration file for a running instance')
     parser.add_argument('--dsn', help='Optional DSN string of the instance to be used as a source \
                                     for config generation. Superuser connection is required.')
+    parser.add_argument('--ignore-listen-port', '-i', action='store_true',
+                        help='Ignore `listen` ports already in use.\
+                              Can only be used with --validate-config')
     args = parser.parse_args()
 
     if args.generate_sample_config:
@@ -269,7 +274,9 @@ def process_arguments() -> Namespace:
         sys.exit(0)
     elif args.validate_config:
         from patroni.config import Config, ConfigParseError
-        from patroni.validator import schema
+        from patroni.validator import populate_validate_params, schema
+
+        populate_validate_params(ignore_listen_port=args.ignore_listen_port)
 
         try:
             Config(args.configfile, validator=schema)

patroni/validator.py

@@ -17,6 +17,17 @@
 from .log import type_logformat
 from .utils import data_directory_is_empty, get_major_version, parse_int, split_host_port
 
+# Additional parameters to fine-tune validation process
+_validation_params: Dict[str, Any] = {}
+
+
+def populate_validate_params(ignore_listen_port: bool = False) -> None:
+    """Populate parameters used to fine-tune the validation of the Patroni config.
+
+    :param ignore_listen_port: ignore the bind failures for the ports marked as `listen`.
+    """
+    _validation_params['ignore_listen_port'] = ignore_listen_port
+
 
 def validate_log_field(field: Union[str, Dict[str, Any], Any]) -> bool:
     """Checks if log field is valid.
@@ -137,7 +148,8 @@ def validate_host_port(host_port: str, listen: bool = False, multiple_hosts: boo
             s = socket.socket(proto[0][0], socket.SOCK_STREAM)
             try:
                 if s.connect_ex((host, port)) == 0:
-                    if listen:
+                    # Do not raise an exception if ignore_listen_port is set to True.
+                    if listen and not _validation_params.get('ignore_listen_port', False):
                         raise ConfigParseError("Port {} is already in use.".format(port))
                 elif not listen:
                     raise ConfigParseError("{} is not reachable".format(host_port))

tests/test_validator.py

@@ -8,7 +8,7 @@
 from unittest.mock import Mock, mock_open, patch
 
 from patroni.dcs import dcs_modules
-from patroni.validator import Directory, schema, Schema
+from patroni.validator import Directory, populate_validate_params, schema, Schema
 
 available_dcs = [m.split(".")[-1] for m in dcs_modules()]
 config = {
@@ -400,3 +400,38 @@ def test_json_log_format(self, *args):
         errors = schema(c)
         output = "\n".join(errors)
         self.assertEqual(['postgresql.bin_dir', 'raft.bind_addr', 'raft.self_addr'], parse_output(output))
+
+    @patch('socket.socket.connect_ex', Mock(return_value=0))
+    def test_bound_port_checks_without_ignore(self, mock_out, mock_err):
+        # When ignore_listen_port is False (default case), an error should be raised if the ports are already bound.
+        c = copy.deepcopy(config)
+        c['restapi']['listen'] = "127.0.0.1:8000"
+        c['postgresql']['listen'] = "127.0.0.1:9000"
+        c['raft']['self_addr'] = "127.0.0.2:9200"
+
+        populate_validate_params(ignore_listen_port=False)
+
+        errors = schema(c)
+        output = "\n".join(errors)
+
+        self.assertEqual(['postgresql.bin_dir', 'postgresql.listen',
+                          'raft.bind_addr', 'restapi.listen'],
+                         parse_output(output))
+
+    @patch('socket.socket.connect_ex', Mock(return_value=0))
+    def test_bound_port_checks_with_ignore(self, mock_out, mock_err):
+        c = copy.deepcopy(config)
+        c['restapi']['listen'] = "127.0.0.1:8000"
+        c['postgresql']['listen'] = "127.0.0.1:9000"
+        c['raft']['self_addr'] = "127.0.0.2:9200"
+        c['raft']['bind_addr'] = "127.0.0.1:9300"
+
+        # Case: When ignore_listen_port is True, error should NOT be raised
+        # even if the ports are already bound.
+        populate_validate_params(ignore_listen_port=True)
+
+        errors = schema(c)
+        output = "\n".join(errors)
+
+        self.assertEqual(['postgresql.bin_dir'],
+                         parse_output(output))