On every node change adjust dbroots in the read-only nodes

Author: mariadb-AlexanderPresniakov

cmapi/cmapi_server/failover_agent.py

@@ -95,9 +95,7 @@ def enterStandbyMode(self, test_mode = False):
         try:
             # TODO: remove test_mode condition and add mock for testing
             if not test_mode:
-                MCSProcessManager.stop_node(
-                    is_primary=nc.is_primary_node(),
-                )
+                MCSProcessManager.stop_node(is_primary=nc.is_primary_node())
             logger.info(
                 'FA.enterStandbyMode(): successfully stopped node.'
             )

cmapi/cmapi_server/handlers/cluster.py

@@ -15,7 +15,7 @@
     get_current_key, get_version, update_revision_and_manager,
 )
 from cmapi_server.node_manipulation import (
-    add_node, add_dbroot, remove_node, switch_node_maintenance,
+    add_node, add_dbroot, remove_node, switch_node_maintenance, update_dbroots_of_readonly_nodes,
 )
 from mcs_node_control.models.misc import get_dbrm_master
 from mcs_node_control.models.node_config import NodeConfig
@@ -181,11 +181,6 @@ def add_node(
                         host=node, input_config_filename=config,
                         output_config_filename=config
                     )
-                else:
-                    logger.debug(
-                        f'Node {node} is read-only, skipping dbroot addition'
-                    )
-
         except Exception as err:
             raise CMAPIBasicError('Error while adding node.') from err
 
@@ -228,6 +223,8 @@ def remove_node(node: str, config: str = DEFAULT_MCS_CONF_PATH) -> dict:
                 node, input_config_filename=config,
                 output_config_filename=config
             )
+            with NodeConfig().modify_config(config) as root:
+                update_dbroots_of_readonly_nodes(root)
         except Exception as err:
             raise CMAPIBasicError('Error while removing node.') from err
 

cmapi/cmapi_server/helpers.py

@@ -378,7 +378,7 @@ async def update_config(node: str, headers: dict, body: dict) -> None:
                 ) as response:
                     resp_json =  await response.json(encoding='utf-8')
                     response.raise_for_status()
-                logging.info(f'Node {node} config put successfull.')
+                logging.info(f'Node {node} config put successful.')
             except aiohttp.ClientResponseError as err:
                 # TODO: may be better to check if resp status is 422 cause
                 #       it's like a signal that cmapi server raised it in

cmapi/cmapi_server/managers/transaction.py

@@ -106,7 +106,7 @@ def rollback_transaction(self, nodes: Optional[list] = None) -> None:
         try:
             rollback_transaction(self.txn_id, nodes=nodes)
             self.active_transaction = False
-            logging.debug(f'Successfull rollback of transaction "{self.txn_id}".')
+            logging.debug(f'Successful rollback of transaction "{self.txn_id}".')
         except Exception:
             logging.error(
                 f'Error while rolling back transaction "{self.txn_id}"',

cmapi/cmapi_server/node_manipulation.py

@@ -113,8 +113,8 @@ def add_node(
                 if not read_only:
                     _rebalance_dbroots(c_root)
                     _move_primary_node(c_root)
-                else:
-                    add_dbroots_of_other_nodes(c_root, pm_num)
+
+            update_dbroots_of_readonly_nodes(c_root)
     except Exception:
         logging.error(
             'Caught exception while adding node, config file is unchanged',
@@ -187,8 +187,7 @@ def remove_node(
                 _rebalance_dbroots(c_root)
                 _move_primary_node(c_root)
 
-            if is_read_only:
-                remove_dbroots_of_node(c_root, pm_num)
+            update_dbroots_of_readonly_nodes(c_root)
         else:
             # TODO:
             #   - IMO undefined behaviour here. Removing one single node
@@ -262,7 +261,7 @@ def rebalance_dbroots(
 #
 # returns the id of the new dbroot on success
 # raises an exception on error
-def add_dbroot(input_config_filename = None, output_config_filename = None, host = None):
+def add_dbroot(input_config_filename = None, output_config_filename = None, host = None) -> int:
     node_config = NodeConfig()
     if input_config_filename is None:
         c_root = node_config.get_current_config_root()
@@ -1185,26 +1184,54 @@ class NodeNotFoundException(Exception):
     pass
 
 
+def get_pm_module_num_to_addr_map(root: etree.Element) -> dict[int, str]:
+    """Get a mapping of PM module numbers to their IP addresses"""
+    module_num_to_addr = {}
+    smc_node = root.find("./SystemModuleConfig")
+    mod_count = int(smc_node.find("./ModuleCount3").text)
+    for i in range(1, mod_count + 1):
+        ip_addr = smc_node.find(f"./ModuleIPAddr{i}-1-3").text
+        module_num_to_addr[i] = ip_addr
+    return module_num_to_addr
+
+
+def update_dbroots_of_readonly_nodes(root: etree.Element) -> None:
+    """Read-only nodes do not have their own dbroots, but they must have all the dbroots of the other nodes
+    So this function sets list of dbroots of each read-only node to the list of all the dbroots in the cluster
+    """
+    nc = NodeConfig()
+    pm_num_to_addr = get_pm_module_num_to_addr_map(root)
+    for ro_node in nc.get_read_only_nodes(root):
+        # Get PM num by IP address
+        this_ip_pm_num = None
+        for pm_num, pm_addr in pm_num_to_addr.items():
+            if pm_addr == ro_node:
+                this_ip_pm_num = pm_num
+                break
+
+        if this_ip_pm_num is not None:
+            # Add dbroots of other nodes to this read-only node
+            add_dbroots_of_other_nodes(root, this_ip_pm_num)
+        else:  # This should not happen
+            err_msg = f"Could not find PM number for read-only node {ro_node}"
+            logging.error(err_msg)
+            raise NodeNotFoundException(err_msg)
+
+
 def add_dbroots_of_other_nodes(root: etree.Element, module_num: int) -> None:
     """Adds all the dbroots listed in the config to this (read-only) node"""
     existing_dbroots = _get_existing_db_roots(root)
     sysconf_node = root.find("./SystemModuleConfig")
 
+    # Remove existing dbroots from this module
+    remove_dbroots_of_node(root, module_num)
+
     # Write node's dbroot count
-    dbroot_count_node = sysconf_node.find(f"./ModuleDBRootCount{module_num}-3")
-    if dbroot_count_node is not None:
-        sysconf_node.remove(dbroot_count_node)
     dbroot_count_node = etree.SubElement(
         sysconf_node, f"ModuleDBRootCount{module_num}-3"
     )
     dbroot_count_node.text = str(len(existing_dbroots))
 
-    # Remove existing dbroot IDs of this module if present
-    for i in range(1, 100):
-        dbroot_id_node = sysconf_node.find(f"./ModuleDBRootID{module_num}-{i}-3")
-        if dbroot_id_node is not None:
-            sysconf_node.remove(dbroot_id_node)
-
     # Write new dbroot IDs to the module mapping
     for i, dbroot_id in enumerate(existing_dbroots, start=1):
         dbroot_id_node = etree.SubElement(
@@ -1221,10 +1248,6 @@ def remove_dbroots_of_node(root: etree.Element, module_num: int) -> None:
     dbroot_count_node = sysconf_node.find(f"./ModuleDBRootCount{module_num}-3")
     if dbroot_count_node is not None:
         sysconf_node.remove(dbroot_count_node)
-    else:
-        logging.error(
-            f"ModuleDBRootCount{module_num}-3 not found in SystemModuleConfig"
-        )
 
     # Remove existing dbroot IDs
     for i in range(1, 100):

cmapi/cmapi_server/test/test_node_manip.py

@@ -1,13 +1,13 @@
 import logging
 import socket
 import unittest
-from unittest.mock import ANY, patch
+from unittest.mock import patch
 
 from lxml import etree
 
 from cmapi_server import node_manipulation
 from cmapi_server.constants import MCS_DATA_PATH
-from cmapi_server.node_manipulation import add_dbroots_of_other_nodes, remove_dbroots_of_node
+from cmapi_server.node_manipulation import add_dbroots_of_other_nodes, remove_dbroots_of_node, update_dbroots_of_readonly_nodes
 from cmapi_server.test.unittest_global import BaseNodeManipTestCase, tmp_mcs_config_filename
 from mcs_node_control.models.node_config import NodeConfig
 
@@ -23,12 +23,18 @@ def test_add_remove_node(self):
             './test-output0.xml','./test-output1.xml','./test-output2.xml'
         )
         hostaddr = socket.gethostbyname(socket.gethostname())
-        node_manipulation.add_node(
-            self.NEW_NODE_NAME, tmp_mcs_config_filename, self.tmp_files[0]
-        )
-        node_manipulation.add_node(
-            hostaddr, self.tmp_files[0], self.tmp_files[1]
-        )
+
+        with patch('cmapi_server.node_manipulation.update_dbroots_of_readonly_nodes') as mock_update_dbroots_of_readonly_nodes:
+            node_manipulation.add_node(
+                self.NEW_NODE_NAME, tmp_mcs_config_filename, self.tmp_files[0]
+            )
+            mock_update_dbroots_of_readonly_nodes.assert_called_once()
+            mock_update_dbroots_of_readonly_nodes.reset_mock()
+
+            node_manipulation.add_node(
+                hostaddr, self.tmp_files[0], self.tmp_files[1]
+            )
+            mock_update_dbroots_of_readonly_nodes.assert_called_once()
 
         # get a NodeConfig, read test.xml
         # look for some of the expected changes.
@@ -42,10 +48,13 @@ def test_add_remove_node(self):
         node = root.find("./ExeMgr2/IPAddr")
         self.assertEqual(node.text, hostaddr)
 
-        node_manipulation.remove_node(
-            self.NEW_NODE_NAME, self.tmp_files[1], self.tmp_files[2],
-            test_mode=True
-        )
+        with patch('cmapi_server.node_manipulation.update_dbroots_of_readonly_nodes') as mock_update_dbroots_of_readonly_nodes:
+            node_manipulation.remove_node(
+                self.NEW_NODE_NAME, self.tmp_files[1], self.tmp_files[2],
+                test_mode=True
+            )
+            mock_update_dbroots_of_readonly_nodes.assert_called_once()
+
         nc = NodeConfig()
         root = nc.get_current_config_root(self.tmp_files[2])
         node = root.find('./PMS1/IPAddr')
@@ -67,8 +76,7 @@ def test_add_remove_read_only_node(self):
         # Mock _rebalance_dbroots and _move_primary_node (only after the first node is added)
         with patch('cmapi_server.node_manipulation._rebalance_dbroots') as mock_rebalance_dbroots, \
              patch('cmapi_server.node_manipulation._move_primary_node') as mock_move_primary_node, \
-             patch('cmapi_server.node_manipulation.add_dbroots_of_other_nodes') as mock_add_dbroots_of_other_nodes, \
-             patch('cmapi_server.node_manipulation.remove_dbroots_of_node') as mock_remove_dbroots_of_node:
+             patch('cmapi_server.node_manipulation.update_dbroots_of_readonly_nodes') as mock_update_dbroots_of_readonly_nodes:
 
             # Add a read-only node
             node_manipulation.add_node(
@@ -94,7 +102,8 @@ def test_add_remove_read_only_node(self):
 
             mock_rebalance_dbroots.assert_not_called()
             mock_move_primary_node.assert_not_called()
-            mock_add_dbroots_of_other_nodes.assert_called_once_with(ANY, 2)
+            mock_update_dbroots_of_readonly_nodes.assert_called_once()
+            mock_update_dbroots_of_readonly_nodes.reset_mock()
 
             # Test read-only node removal
             node_manipulation.remove_node(
@@ -109,7 +118,7 @@ def test_add_remove_read_only_node(self):
 
             mock_rebalance_dbroots.assert_not_called()
             mock_move_primary_node.assert_not_called()
-            mock_remove_dbroots_of_node.assert_called_once_with(ANY, 2)
+            mock_update_dbroots_of_readonly_nodes.assert_called_once()
 
 
     def test_add_dbroots_nodes_rebalance(self):
@@ -271,13 +280,23 @@ def test_unassign_dbroot1(self):
         self.assertTrue(caught_it)
 
 
-class TestReadOnlyNodeDBRootsManip(unittest.TestCase):
-    our_module_idx = 2
+class TestDBRootsManipulation(unittest.TestCase):
+    our_module_idx = 3
+    ro_node1_ip = '192.168.1.3'
+    ro_node2_ip = '192.168.1.4'
 
     def setUp(self):
-        # Mock initial XML structure (add two dbroots)
+        # Mock initial XML structure (add two nodes and two dbroots)
         self.root = etree.Element('Columnstore')
-        etree.SubElement(self.root, 'SystemModuleConfig')
+        # Add two PM modules with IP addresses
+        smc = etree.SubElement(self.root, 'SystemModuleConfig')
+        module_count = etree.SubElement(smc, 'ModuleCount3')
+        module_count.text = '2'
+        module1_ip = etree.SubElement(smc, 'ModuleIPAddr1-1-3')
+        module1_ip.text = '192.168.1.1'
+        module2_ip = etree.SubElement(smc, 'ModuleIPAddr2-1-3')
+        module2_ip.text = '192.168.1.2'
+
         system_config = etree.SubElement(self.root, 'SystemConfig')
         dbroot_count = etree.SubElement(system_config, 'DBRootCount')
         dbroot_count.text = '2'
@@ -286,6 +305,15 @@ def setUp(self):
         dbroot2 = etree.SubElement(system_config, 'DBRoot2')
         dbroot2.text = '/data/dbroot2'
 
+    def test_get_pm_module_num_to_addr_map(self):
+        result = node_manipulation.get_pm_module_num_to_addr_map(self.root)
+
+        expected = {
+            1: '192.168.1.1',
+            2: '192.168.1.2',
+        }
+        self.assertEqual(result, expected)
+
     def test_add_dbroots_of_other_nodes(self):
         '''add_dbroots_of_other_nodes must add dbroots of other nodes into mapping of the node.'''
         add_dbroots_of_other_nodes(self.root, self.our_module_idx)
@@ -325,3 +353,36 @@ def test_remove_dbroots_of_node(self):
         dbroot2 = self.root.find(f'./SystemModuleConfig/ModuleDBRootID{self.our_module_idx}-2-3')
         self.assertIsNone(dbroot1)
         self.assertIsNone(dbroot2)
+
+    def test_update_dbroots_of_readonly_nodes(self):
+        """Test that update_dbroots_of_readonly_nodes adds all existing dbroots to all existing read-only nodes"""
+        # Add two new new modules to the XML structure (two already exist)
+        smc = self.root.find('./SystemModuleConfig')
+        module_count = smc.find('./ModuleCount3')
+        module_count.text = '4'
+        module3_ip = etree.SubElement(smc, 'ModuleIPAddr3-1-3')
+        module3_ip.text = self.ro_node1_ip
+        module4_ip = etree.SubElement(smc, 'ModuleIPAddr4-1-3')
+        module4_ip.text = self.ro_node2_ip
+        # Add them to ReadOnlyNodes
+        read_only_nodes = etree.SubElement(self.root, 'ReadOnlyNodes')
+        for ip in [self.ro_node1_ip, self.ro_node2_ip]:
+            node = etree.SubElement(read_only_nodes, 'Node')
+            node.text = ip
+
+        update_dbroots_of_readonly_nodes(self.root)
+
+        # Check that read only nodes have all the dbroots
+        for ro_module_idx in range(3, 5):
+            module_count = self.root.find(f'./SystemModuleConfig/ModuleDBRootCount{ro_module_idx}-3')
+            self.assertIsNotNone(module_count)
+            self.assertEqual(module_count.text, '2')
+
+            dbroot1 = self.root.find(f'./SystemModuleConfig/ModuleDBRootID{ro_module_idx}-1-3')
+            dbroot2 = self.root.find(f'./SystemModuleConfig/ModuleDBRootID{ro_module_idx}-2-3')
+            self.assertIsNotNone(dbroot1)
+            self.assertIsNotNone(dbroot2)
+            self.assertEqual(dbroot1.text, '1')
+            self.assertEqual(dbroot2.text, '2')
+
+

cmapi/mcs_node_control/models/node_config.py

@@ -1,4 +1,5 @@
 import configparser
+from contextlib import contextmanager
 import grp
 import logging
 import pwd
@@ -7,6 +8,7 @@
 from os import chown, mkdir, replace
 from pathlib import Path
 from shutil import copyfile
+from typing import Optional
 from xml.dom import minidom  # to pick up pretty printing functionality
 
 from lxml import etree
@@ -136,6 +138,26 @@ def write_config(self, tree, filename=DEFAULT_MCS_CONF_PATH):
             f.write(self.to_string(tree))
         replace(tmp_filename, filename)    # atomic replacement
 
+    @contextmanager
+    def modify_config(
+        self,
+        input_config_filename: str = DEFAULT_MCS_CONF_PATH,
+        output_config_filename: Optional[str] = None,
+        ):
+        """Context manager to modify the config file
+        If exception is raised, the config file is not modified and exception is re-raised
+        If output_config_filename is not provided, the input config file is modified
+        """
+        try:
+            c_root = self.get_current_config_root(input_config_filename)
+            yield c_root
+        except Exception as e:
+            logging.error(f"modify_config(): Caught exception: '{str(e)}', config file not modified")
+            raise
+        else:
+            output_config_filename = output_config_filename or input_config_filename
+            self.write_config(c_root, output_config_filename)
+
     def to_string(self, tree):
         # TODO: try to use lxml to do this to avoid the add'l dependency
         xmlstr = minidom.parseString(etree.tostring(tree)).toprettyxml(