From 69e23a586a176b36f25d58dfeea9f8f68a3e3f62 Mon Sep 17 00:00:00 2001 From: Paulo Machado Date: Mon, 29 Apr 2024 14:59:16 -0300 Subject: [PATCH 1/3] refactor hostname resolution with maas fix --- poetry.lock | 34 +++---- pyproject.toml | 1 + src/hostname_resolution.py | 134 +++++++------------------ tests/unit/test_backups.py | 6 +- tests/unit/test_charm.py | 2 +- tests/unit/test_hostname_resolution.py | 62 ++++++++++++ 6 files changed, 117 insertions(+), 122 deletions(-) create mode 100644 tests/unit/test_hostname_resolution.py diff --git a/poetry.lock b/poetry.lock index c976c42d2..8c99a9d7a 100644 --- a/poetry.lock +++ b/poetry.lock @@ -982,16 +982,6 @@ files = [ {file = "MarkupSafe-2.1.3-cp311-cp311-musllinux_1_1_x86_64.whl", hash = "sha256:5bbe06f8eeafd38e5d0a4894ffec89378b6c6a625ff57e3028921f8ff59318ac"}, {file = "MarkupSafe-2.1.3-cp311-cp311-win32.whl", hash = "sha256:dd15ff04ffd7e05ffcb7fe79f1b98041b8ea30ae9234aed2a9168b5797c3effb"}, {file = "MarkupSafe-2.1.3-cp311-cp311-win_amd64.whl", hash = "sha256:134da1eca9ec0ae528110ccc9e48041e0828d79f24121a1a146161103c76e686"}, - 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on = IPAddressChangeCharmEvents() + on = ( # pyright: ignore [reportIncompatibleMethodOverride, reportAssignmentType + IPAddressChangeCharmEvents() + ) def __init__(self, charm: "MySQLOperatorCharm"): super().__init__(charm, "hostname-resolution") @@ -38,12 +41,8 @@ def __init__(self, charm: "MySQLOperatorCharm"): self.framework.observe(self.charm.on.config_changed, self._update_host_details_in_databag) self.framework.observe(self.on.ip_address_change, self._update_host_details_in_databag) - self.framework.observe( - self.charm.on[PEER].relation_changed, self._potentially_update_etc_hosts - ) - self.framework.observe( - self.charm.on[PEER].relation_departed, self._remove_host_from_etc_hosts - ) + self.framework.observe(self.charm.on[PEER].relation_changed, self._update_etc_hosts) + self.framework.observe(self.charm.on[PEER].relation_departed, self._update_etc_hosts) self.ip_address_observer.start_observer() @@ -60,111 +59,54 @@ def _update_host_details_in_databag(self, _) -> None: logger.exception("Unable to get local IP address") ip = "127.0.0.1" - host_details = { - "hostname": hostname, - "fqdn": fqdn, - "ip": ip, - } + host_details = {"names": [hostname, fqdn], "address": ip} self.charm.unit_peer_data[HOSTNAME_DETAILS] = json.dumps(host_details) - def _get_host_details(self) -> dict[str, str]: - host_details = {} + def _get_host_details(self) -> list[HostsEntry]: + host_details = list() + + if not self.charm.peers: + return [] for key, data in self.charm.peers.data.items(): if isinstance(key, Unit) and data.get(HOSTNAME_DETAILS): unit_details = json.loads(data[HOSTNAME_DETAILS]) - unit_details["unit"] = key.name - host_details[unit_details["hostname"]] = unit_details - - return host_details - - def _does_etc_hosts_need_update(self, host_details: dict[str, str]) -> bool: - outdated_hosts = host_details.copy() - with open("/etc/hosts", "r") as hosts_file: - for line in hosts_file: - if "# unit=" not in line: - continue + if unit_details.get("address"): + entry = HostsEntry(comment=COMMENT, entry_type="ipv4", **unit_details) + else: + # case when migrating from old format + entry = HostsEntry( + address=unit_details["ip"], + names=[unit_details["hostname"], unit_details["fqdn"]], + comment=COMMENT, + entry_type="ipv4", + ) - ip, fqdn, hostname = line.split("#")[0].strip().split() - if outdated_hosts.get(hostname).get("ip") == ip: - outdated_hosts.pop(hostname) + host_details.append(entry) - return bool(outdated_hosts) + return host_details - def _potentially_update_etc_hosts(self, _) -> None: + def _update_etc_hosts(self, _) -> None: """Potentially update the /etc/hosts file with new hostname to IP for units.""" if not self.charm._is_peer_data_set: return - host_details = self._get_host_details() - if not host_details: + host_entries = self._get_host_details() + if not host_entries: logger.debug("No hostnames in the peer databag. Skipping update of /etc/hosts") return - if not self._does_etc_hosts_need_update(host_details): - logger.debug("No hostnames in /etc/hosts changed. Skipping update to /etc/hosts") - return - - hosts_in_file = [] - - with io.StringIO() as updated_hosts_file: - with open("/etc/hosts", "r") as hosts_file: - for line in hosts_file: - if "# unit=" not in line: - updated_hosts_file.write(line) - continue - - for hostname, details in host_details.items(): - if hostname == line.split()[2]: - hosts_in_file.append(hostname) - - fqdn, ip, unit = details["fqdn"], details["ip"], details["unit"] - - logger.debug( - f"Overwriting {hostname} ({unit=}) with {ip=}, {fqdn=} in /etc/hosts" - ) - updated_hosts_file.write(f"{ip} {fqdn} {hostname} # unit={unit}\n") - break - - for hostname, details in host_details.items(): - if hostname not in hosts_in_file: - fqdn, ip, unit = details["fqdn"], details["ip"], details["unit"] - - logger.debug(f"Adding {hostname} ({unit=} with {ip=}, {fqdn=} in /etc/hosts") - updated_hosts_file.write(f"{ip} {fqdn} {hostname} # unit={unit}\n") - - with open("/etc/hosts", "w") as hosts_file: - hosts_file.write(updated_hosts_file.getvalue()) - - try: - self.charm._mysql.flush_host_cache() - except MySQLFlushHostCacheError: - self.charm.unit.status = BlockedStatus("Unable to flush MySQL host cache") - - def _remove_host_from_etc_hosts(self, event: RelationDepartedEvent) -> None: - departing_unit_name = event.unit.name - - logger.debug(f"Checking if an entry for {departing_unit_name} is in /etc/hosts") - with open("/etc/hosts", "r") as hosts_file: - for line in hosts_file: - if f"# unit={departing_unit_name}" in line: - break - else: - return - - logger.debug(f"Removing entry for {departing_unit_name} from /etc/hosts") - with io.StringIO() as updated_hosts_file: - with open("/etc/hosts", "r") as hosts_file: - for line in hosts_file: - if f"# unit={departing_unit_name}" not in line: - updated_hosts_file.write(line) - - with open("/etc/hosts", "w") as hosts_file: - hosts_file.write(updated_hosts_file.getvalue()) + logger.debug("Updating /etc/hosts with new hostname to IP mappings") + hosts = Hosts() + hosts.remove_all_matching(comment=COMMENT) + # remove MAAS entry + hosts.remove_all_matching(address="127.0.1.1") + hosts.add(host_entries) + hosts.write() try: self.charm._mysql.flush_host_cache() except MySQLFlushHostCacheError: - self.charm.unit.status = BlockedStatus("Unable to flush MySQL host cache") + logger.warning("Unable to flush MySQL host cache") diff --git a/tests/unit/test_backups.py b/tests/unit/test_backups.py index 86b171b6f..02e0bdfb3 100644 --- a/tests/unit/test_backups.py +++ b/tests/unit/test_backups.py @@ -329,7 +329,7 @@ def test_can_unit_perform_backup( @patch_network_get(private_address="1.1.1.1") @patch("mysql_vm_helpers.MySQL.offline_mode_and_hidden_instance_exists", return_value=False) @patch("mysql_vm_helpers.MySQL.get_member_state") - @patch("hostname_resolution.MySQLMachineHostnameResolution._remove_host_from_etc_hosts") + @patch("python_hosts.Hosts.write") def test_can_unit_perform_backup_failure( self, _, @@ -381,7 +381,7 @@ def test_can_unit_perform_backup_failure( @patch_network_get(private_address="1.1.1.1") @patch("mysql_vm_helpers.MySQL.set_instance_option") @patch("mysql_vm_helpers.MySQL.set_instance_offline_mode") - @patch("hostname_resolution.MySQLMachineHostnameResolution._remove_host_from_etc_hosts") + @patch("python_hosts.Hosts.write") def test_pre_backup( self, _, @@ -551,7 +551,7 @@ def test_pre_restore_checks( @patch_network_get(private_address="1.1.1.1") @patch("mysql_vm_helpers.MySQL.is_server_connectable", return_value=True) @patch("charm.MySQLOperatorCharm.is_unit_busy", return_value=False) - @patch("hostname_resolution.MySQLMachineHostnameResolution._remove_host_from_etc_hosts") + @patch("python_hosts.Hosts.write") def test_pre_restore_checks_failure( self, _, diff --git a/tests/unit/test_charm.py b/tests/unit/test_charm.py index 247d1a29d..e91b721b9 100644 --- a/tests/unit/test_charm.py +++ b/tests/unit/test_charm.py @@ -290,7 +290,7 @@ def test_on_start_exceptions( @patch("charm.is_volume_mounted", return_value=True) @patch("mysql_vm_helpers.MySQL.reboot_from_complete_outage") @patch("charm.snap_service_operation") - @patch("hostname_resolution.MySQLMachineHostnameResolution._remove_host_from_etc_hosts") + @patch("python_hosts.Hosts.write") def test_on_update( self, _, diff --git a/tests/unit/test_hostname_resolution.py b/tests/unit/test_hostname_resolution.py new file mode 100644 index 000000000..3e32f8879 --- /dev/null +++ b/tests/unit/test_hostname_resolution.py @@ -0,0 +1,62 @@ +# Copyright 2024 Canonical Ltd. +# See LICENSE file for licensing details. + +import json +import unittest +from unittest.mock import patch + +from ops.testing import Harness + +from charm import MySQLOperatorCharm +from constants import HOSTNAME_DETAILS, PEER + +APP_NAME = "mysql" + + +class TestHostnameResolution(unittest.TestCase): + def setUp(self): + self.harness = Harness(MySQLOperatorCharm) + self.addCleanup(self.harness.cleanup) + self.harness.begin() + self.charm = self.harness.charm + self.hostname_resolution = self.charm.hostname_resolution + + def test_get_host_details(self): + """Test get_peer_host_details method.""" + host_entries = self.hostname_resolution._get_host_details() + + # before relation + self.assertEqual(host_entries, []) + + # Add relation + id = self.harness.add_relation(PEER, APP_NAME) + + host_entries = self.hostname_resolution._get_host_details() + self.assertEqual(host_entries, []) + + # Add unit + self.harness.add_relation_unit(id, f"{APP_NAME}/0") + self.harness.update_relation_data( + id, + f"{APP_NAME}/0", + { + HOSTNAME_DETAILS: json.dumps( + {"address": "1.1.1.1", "names": ["name1", "name2", "name3"]} + ) + }, + ) + + host_entries = self.hostname_resolution._get_host_details() + self.assertEqual(len(host_entries), 1) + self.assertEqual(host_entries[0].address, "1.1.1.1") + + @patch("socket.gethostname", return_value="mysql-0") + def test_update_host_details_in_databag(self, _gethostname_mock): + """Test update_host_details_in_databag method.""" + # Add relation + self.harness.add_relation(PEER, APP_NAME) + self.assertEqual(self.charm.unit_peer_data.get(HOSTNAME_DETAILS), None) + self.hostname_resolution._update_host_details_in_databag(None) + _gethostname_mock.assert_called() + + self.assertTrue("mysql-0" in self.charm.unit_peer_data[HOSTNAME_DETAILS]) From b8410853cc783000e3d720cf681ae4b1a0ade07c Mon Sep 17 00:00:00 2001 From: Paulo Machado Date: Mon, 29 Apr 2024 16:26:49 -0300 Subject: [PATCH 2/3] call on init --- src/charm.py | 3 +++ src/hostname_resolution.py | 6 +++--- 2 files changed, 6 insertions(+), 3 deletions(-) diff --git a/src/charm.py b/src/charm.py index c014748c9..2acf766bb 100755 --- a/src/charm.py +++ b/src/charm.py @@ -620,6 +620,9 @@ def workload_initialise(self) -> None: self._mysql.reset_root_password_and_start_mysqld() self._mysql.configure_mysql_users() + # ensure hostname can be resolved + self.hostname_resolution.update_etc_hosts(None) + current_mysqld_pid = self._mysql.get_pid_of_port_3306() self._mysql.configure_instance() diff --git a/src/hostname_resolution.py b/src/hostname_resolution.py index a6d880f62..fecdd15f9 100644 --- a/src/hostname_resolution.py +++ b/src/hostname_resolution.py @@ -41,8 +41,8 @@ def __init__(self, charm: "MySQLOperatorCharm"): self.framework.observe(self.charm.on.config_changed, self._update_host_details_in_databag) self.framework.observe(self.on.ip_address_change, self._update_host_details_in_databag) - self.framework.observe(self.charm.on[PEER].relation_changed, self._update_etc_hosts) - self.framework.observe(self.charm.on[PEER].relation_departed, self._update_etc_hosts) + self.framework.observe(self.charm.on[PEER].relation_changed, self.update_etc_hosts) + self.framework.observe(self.charm.on[PEER].relation_departed, self.update_etc_hosts) self.ip_address_observer.start_observer() @@ -88,7 +88,7 @@ def _get_host_details(self) -> list[HostsEntry]: return host_details - def _update_etc_hosts(self, _) -> None: + def update_etc_hosts(self, _) -> None: """Potentially update the /etc/hosts file with new hostname to IP for units.""" if not self.charm._is_peer_data_set: return From 89a4e35939d3a776abae5587d1624d261db23517 Mon Sep 17 00:00:00 2001 From: Paulo Machado Date: Thu, 2 May 2024 07:38:43 -0300 Subject: [PATCH 3/3] proper version definition and more specific offending address filtering --- poetry.lock | 2 +- pyproject.toml | 2 +- src/hostname_resolution.py | 8 ++++++-- 3 files changed, 8 insertions(+), 4 deletions(-) diff --git a/poetry.lock b/poetry.lock index 8c99a9d7a..8380e1b89 100644 --- a/poetry.lock +++ b/poetry.lock @@ -2285,4 +2285,4 @@ files = [ [metadata] lock-version = "2.0" python-versions = "^3.10" -content-hash = "477753bd453eedd4d35c7ffd8ba61cf8b269ee593e0886e731b0b2f910d11f92" +content-hash = "099499829dacf52d7a1bb57bb08d1c85204c062c1536e319a5319d7e797b6962" diff --git a/pyproject.toml b/pyproject.toml index ac9ea4c82..8253e17f1 100644 --- a/pyproject.toml +++ b/pyproject.toml @@ -17,7 +17,7 @@ boto3 = "^1.28.23" pyopenssl = "^24.0.0" typing_extensions = "^4.7.1" jinja2 = "^3.1.2" -python_hosts = "*" +python_hosts = "^1.0.6" [tool.poetry.group.charm-libs.dependencies] # data_platform_libs/v0/data_interfaces.py diff --git a/src/hostname_resolution.py b/src/hostname_resolution.py index fecdd15f9..471a971e2 100644 --- a/src/hostname_resolution.py +++ b/src/hostname_resolution.py @@ -100,9 +100,13 @@ def update_etc_hosts(self, _) -> None: logger.debug("Updating /etc/hosts with new hostname to IP mappings") hosts = Hosts() + + if hosts.exists(address="127.0.1.1", names=[socket.getfqdn()]): + # remove MAAS injected entry + logger.debug("Removing MAAS injected entry from /etc/hosts") + hosts.remove_all_matching(address="127.0.1.1") + hosts.remove_all_matching(comment=COMMENT) - # remove MAAS entry - hosts.remove_all_matching(address="127.0.1.1") hosts.add(host_entries) hosts.write()