Re: [PR] Optionally retry db connection errors related to temporary DNS failures [airflow]
github-actions[bot] closed pull request #51586: Optionally retry db connection errors related to temporary DNS failures URL: https://github.com/apache/airflow/pull/51586 -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
Re: [PR] Optionally retry db connection errors related to temporary DNS failures [airflow]
github-actions[bot] commented on PR #51586: URL: https://github.com/apache/airflow/pull/51586#issuecomment-3146046517 This pull request has been automatically marked as stale because it has not had recent activity. It will be closed in 5 days if no further activity occurs. Thank you for your contributions. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
Re: [PR] Optionally retry db connection errors related to temporary DNS failures [airflow]
xBis7 commented on code in PR #51586: URL: https://github.com/apache/airflow/pull/51586#discussion_r2152508591 ## airflow-core/src/airflow/config_templates/config.yml: ## @@ -679,6 +679,39 @@ database: type: integer example: ~ default: "1" +check_db_discovery: Review Comment: I understand what you are saying and we are going to look for configuration issues but the root of the problem isn't fractional CPU allocation. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
Re: [PR] Optionally retry db connection errors related to temporary DNS failures [airflow]
potiuk commented on code in PR #51586: URL: https://github.com/apache/airflow/pull/51586#discussion_r2150786168 ## airflow-core/src/airflow/config_templates/config.yml: ## @@ -679,6 +679,39 @@ database: type: integer example: ~ default: "1" +check_db_discovery: Review Comment: So you should talk to your k8s infra guys (if you have a separate team to manage your k8S) - not to your airflow team. But I have no idea whatsoever how your team is organised and who is responsible for what, so it's hard for me to give you advice on who in your organisation you should talk to. But ... DNS is a k8s infra thing. You need to have DNS working for any app running on top of k8s (or anything else) if your team is managing just airflow, they are not managing DNS on your K8S. That's important distinction. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
Re: [PR] Optionally retry db connection errors related to temporary DNS failures [airflow]
potiuk commented on code in PR #51586: URL: https://github.com/apache/airflow/pull/51586#discussion_r2150772248 ## airflow-core/src/airflow/config_templates/config.yml: ## @@ -679,6 +679,39 @@ database: type: integer example: ~ default: "1" +check_db_discovery: Review Comment: I am not talking about Airflow. I am talking about DNS . Thos is part of the K8S infrastructure, not Airflow - you seem to be mixing things. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
Re: [PR] Optionally retry db connection errors related to temporary DNS failures [airflow]
potiuk commented on code in PR #51586: URL: https://github.com/apache/airflow/pull/51586#discussion_r2150772248 ## airflow-core/src/airflow/config_templates/config.yml: ## @@ -679,6 +679,39 @@ database: type: integer example: ~ default: "1" +check_db_discovery: Review Comment: I am not talking about Airflow. I am talking about DNS . This is part of the K8S infrastructure, not Airflow - you seem to be mixing things. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
Re: [PR] Optionally retry db connection errors related to temporary DNS failures [airflow]
xBis7 commented on code in PR #51586: URL: https://github.com/apache/airflow/pull/51586#discussion_r2150406548 ## airflow-core/src/airflow/config_templates/config.yml: ## @@ -679,6 +679,39 @@ database: type: integer example: ~ default: "1" +check_db_discovery: Review Comment: @potiuk According to my team, airflow is running on multiple pods that each one has 2 CPU cores. There is no fractional CPU allocation. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
Re: [PR] Optionally retry db connection errors related to temporary DNS failures [airflow]
xBis7 commented on code in PR #51586: URL: https://github.com/apache/airflow/pull/51586#discussion_r2145504425 ## airflow-core/src/airflow/config_templates/config.yml: ## @@ -679,6 +679,39 @@ database: type: integer example: ~ default: "1" +check_db_discovery: Review Comment: @potiuk Thank you for the info! Let me check with the team and get back to you. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
Re: [PR] Optionally retry db connection errors related to temporary DNS failures [airflow]
potiuk commented on code in PR #51586: URL: https://github.com/apache/airflow/pull/51586#discussion_r2145098824 ## airflow-core/src/airflow/config_templates/config.yml: ## @@ -679,6 +679,39 @@ database: type: integer example: ~ default: "1" +check_db_discovery: Review Comment: I am not sure we really want it - this seems to be band-aid for misconfiguration of K8S and it only works for one specific case (database lookup) which is likely one of many cases where temporary blip in DNS might cause even more problems. Any time you communicate with another POD - you get DNS lookup, any time you want to send message to broker you get DNS lookup, etc. etc. Adding 4 new configuration options to the list of few 100s we already have to handle this single case seems quite wrong. Instead one should look at their K8S configuration and see why there are DNS errors and eliminate them. From the experience of others - the problem is that in many installation k8s DNS is configured with fractional CPU (often 0.1 = 100ms) - and the way how k8s slicing works in this case is that if during 0.1 s you DNS is busy, it will stop responding for the raminder of the second. And the way to fix it is to configure your DNS to not have fractional CPU allocation. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
Re: [PR] Optionally retry db connection errors related to temporary DNS failures [airflow]
potiuk commented on code in PR #51586: URL: https://github.com/apache/airflow/pull/51586#discussion_r2145098824 ## airflow-core/src/airflow/config_templates/config.yml: ## @@ -679,6 +679,39 @@ database: type: integer example: ~ default: "1" +check_db_discovery: Review Comment: I am not sure we really want it - this seems to be band-aid for misconfiguration of K8S and it only works for one specific case (database lookup) which is likely one of many cases where temporary blip in DNS might cause even more problems. Any time you communicate with another POD - you get DNS lookup, any time you want to send message to broker you get DNS lookup, etc. etc. Adding 4 new configuration options to the list of few 100s we already have to handle this single case seems quite wrong. Instead one should look at their K8S configuration and see why there are DNS errors and eliminate them. From the experience of others - the problem is that in many installation k8s DNS is configured with fractional CPU (0.1) - and the way how k8s slicing works in this case is that if during 0.1 s you DNS is busy, it will stop responding for the raminder of the second. And the way to fix it is to configure your DNS to not have fractional CPU allocation. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
Re: [PR] Optionally retry db connection errors related to temporary DNS failures [airflow]
potiuk commented on code in PR #51586: URL: https://github.com/apache/airflow/pull/51586#discussion_r2145098824 ## airflow-core/src/airflow/config_templates/config.yml: ## @@ -679,6 +679,39 @@ database: type: integer example: ~ default: "1" +check_db_discovery: Review Comment: I am not sure we really want it - this seems to be band-aid for misconfiguration of K8S and it only works for one specific case (database lookup) which is likely one of many cases where temporary blip in DNS might cause even more problems. Any time you communicate with another POD - you get DNS lookup, any time you want to send message to broker you get DNS lookup, etc. etc. Adding 4 new configuration options to the list of few 100s we already have to handle this single case seems quite wrong. Instead one should look at their K8S configuration and see why there are DNS errors and eliminate them. From the experience of others - the problem is that in many installation k8s DNS is confifgured with fractional CPU (0.1) - and the way how k8s slicing works in this case is that if during 0.1 s you DNS is busy, it will stop responding for the raminder of the second. And the way to fix it is to configure your DNS to not have fractional CPU allocation. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
Re: [PR] Optionally retry db connection errors related to temporary DNS failures [airflow]
xBis7 commented on PR #51586: URL: https://github.com/apache/airflow/pull/51586#issuecomment-2967302934 @jason810496 Thank you, I addressed your new comments. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
Re: [PR] Optionally retry db connection errors related to temporary DNS failures [airflow]
xBis7 commented on code in PR #51586:
URL: https://github.com/apache/airflow/pull/51586#discussion_r2143064168
##
airflow-core/tests/unit/core/test_db_discovery.py:
##
@@ -0,0 +1,165 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements. See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership. The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License. You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied. See the License for the
+# specific language governing permissions and limitations
+# under the License.
+from __future__ import annotations
+
+import contextlib
+import logging
+import os
+import shutil
+import socket
+import time
+from unittest.mock import patch
+
+import pytest
+from sqlalchemy import text
+
+from airflow import settings
+from airflow.utils import db_discovery
+from airflow.utils.db_discovery import DbDiscoveryStatus
+
+from tests_common.test_utils.config import conf_vars
+
+log = logging.getLogger(__name__)
+
+
+def dispose_connection_pool():
+"""Dispose any cached sockets so that the next query will force a new
connect."""
+settings.engine.dispose()
+# Wait for SqlAlchemy.
+time.sleep(0.5)
+
+
+def make_db_test_call():
+"""
+Create a session and execute a query.
+
+It will establish a new connection if there isn't one available.
+New connections use DNS lookup.
+"""
+from airflow.utils.session import create_session
+
+with create_session() as session:
+session.execute(text("SELECT 1"))
+
+
+def assert_query_raises_exc(expected_error_msg: str, expected_status: str,
expected_retry_num: int):
+with pytest.raises(socket.gaierror, match=expected_error_msg):
+make_db_test_call()
+
+assert len(db_discovery.db_health_status) == 2
+
+assert db_discovery.db_health_status[0] == expected_status
+assert db_discovery.db_retry_count == expected_retry_num
+
+
[email protected]("postgres")
+class TestDbDiscoveryIntegration:
Review Comment:
I added a common fixture that will be auto used.
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Re: [PR] Optionally retry db connection errors related to temporary DNS failures [airflow]
xBis7 commented on code in PR #51586:
URL: https://github.com/apache/airflow/pull/51586#discussion_r2143019695
##
airflow-core/src/airflow/utils/db_discovery.py:
##
@@ -0,0 +1,127 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements. See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership. The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License. You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied. See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+from __future__ import annotations
+
+import logging
+import socket
+import time
+
+import tenacity
+from sqlalchemy.engine.url import make_url
+
+from airflow.configuration import conf
+
+logger = logging.getLogger(__name__)
+
+
+class DbDiscoveryStatus:
+"""Enum with the return value for `check_db_discovery_if_needed()`."""
+
+# The hostname resolves.
+OK = "ok"
+# There has been some temporary DNS lookup blip and the connection will
probably recover.
+# Causes: a dns timeout or a temporary network issue.
+TEMPORARY_ERROR = "dns_temporary_failure"
+# Unknown hostname or service, this is permanent and the connection can't
be recovered.
+# Causes: a cmd or config typo, a hostname that doesn't exist.
+UNKNOWN_HOSTNAME = "unknown_hostname"
+# Unknown hostname or service, this is permanent and the connection can't
be recovered.
+# Causes: Failed DNS server or config typo.
+PERMANENT_ERROR = "dns_permanent_failure"
+# Some other error.
+UNKNOWN_ERROR = "unknown_error"
+
+
+# db status - how long ago it was retrieved
+db_health_status: tuple[str, float] = (DbDiscoveryStatus.OK, 0.0)
+
+# TODO: For now, this is used for testing
+# but it can also be used to add stats.
+db_retry_count: int = 0
+
+
+def _is_temporary_dns_error(ex: BaseException) -> bool:
+return isinstance(ex, socket.gaierror) and ex.errno == socket.EAI_AGAIN
Review Comment:
Sure.
##
airflow-core/src/airflow/utils/session.py:
##
@@ -38,6 +40,20 @@ def create_session(scoped: bool = True) ->
Generator[SASession, None, None]:
Session = getattr(settings, "NonScopedSession", None)
if Session is None:
raise RuntimeError("Session must be set before!")
+
+check_db_discovery = conf.getboolean("database", "check_db_discovery")
+db_discovery_retries = conf.getint("database", "max_db_discovery_retries")
+db_discovery_initial_wait = conf.getfloat("database",
"db_discovery_initial_wait_time")
+db_discovery_max_wait = conf.getfloat("database",
"db_discovery_max_wait_time")
+# If there is an exception, it will be raised
+# in order to prevent the session from unnecessarily being created.
+if check_db_discovery:
+check_db_discovery_with_retries(
+retry_num=db_discovery_retries,
+initial_retry_wait=db_discovery_initial_wait,
+max_retry_wait=db_discovery_max_wait,
+)
Review Comment:
Done.
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Re: [PR] Optionally retry db connection errors related to temporary DNS failures [airflow]
jason810496 commented on code in PR #51586:
URL: https://github.com/apache/airflow/pull/51586#discussion_r2142863942
##
airflow-core/tests/unit/core/test_db_discovery.py:
##
@@ -0,0 +1,165 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements. See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership. The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License. You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied. See the License for the
+# specific language governing permissions and limitations
+# under the License.
+from __future__ import annotations
+
+import contextlib
+import logging
+import os
+import shutil
+import socket
+import time
+from unittest.mock import patch
+
+import pytest
+from sqlalchemy import text
+
+from airflow import settings
+from airflow.utils import db_discovery
+from airflow.utils.db_discovery import DbDiscoveryStatus
+
+from tests_common.test_utils.config import conf_vars
+
+log = logging.getLogger(__name__)
+
+
+def dispose_connection_pool():
+"""Dispose any cached sockets so that the next query will force a new
connect."""
+settings.engine.dispose()
+# Wait for SqlAlchemy.
+time.sleep(0.5)
+
+
+def make_db_test_call():
+"""
+Create a session and execute a query.
+
+It will establish a new connection if there isn't one available.
+New connections use DNS lookup.
+"""
+from airflow.utils.session import create_session
+
+with create_session() as session:
+session.execute(text("SELECT 1"))
+
+
+def assert_query_raises_exc(expected_error_msg: str, expected_status: str,
expected_retry_num: int):
+with pytest.raises(socket.gaierror, match=expected_error_msg):
+make_db_test_call()
+
+assert len(db_discovery.db_health_status) == 2
+
+assert db_discovery.db_health_status[0] == expected_status
+assert db_discovery.db_retry_count == expected_retry_num
+
+
[email protected]("postgres")
+class TestDbDiscoveryIntegration:
Review Comment:
How about adding 2 fixtures:
1. for `db_discovery` module setup/ teardown, maybe called (
`prepare_db_discovery` )
Somehow like:
```python
dispose_connection_pool()
yield
# Reset the values for the next tests.
db_discovery.db_health_status = (DbDiscoveryStatus.OK, 0.0)
db_discovery.db_retry_count = 0
```
2. another fixture is for dns resolution config
Then all the case can use these fixture with `@pytest.mark.usefixtures` if
needed.
##
airflow-core/src/airflow/utils/session.py:
##
@@ -38,6 +40,20 @@ def create_session(scoped: bool = True) ->
Generator[SASession, None, None]:
Session = getattr(settings, "NonScopedSession", None)
if Session is None:
raise RuntimeError("Session must be set before!")
+
+check_db_discovery = conf.getboolean("database", "check_db_discovery")
+db_discovery_retries = conf.getint("database", "max_db_discovery_retries")
+db_discovery_initial_wait = conf.getfloat("database",
"db_discovery_initial_wait_time")
+db_discovery_max_wait = conf.getfloat("database",
"db_discovery_max_wait_time")
+# If there is an exception, it will be raised
+# in order to prevent the session from unnecessarily being created.
+if check_db_discovery:
+check_db_discovery_with_retries(
+retry_num=db_discovery_retries,
+initial_retry_wait=db_discovery_initial_wait,
+max_retry_wait=db_discovery_max_wait,
+)
Review Comment:
nit:
```suggestion
# If there is an exception, it will be raised
# in order to prevent the session from unnecessarily being created.
if conf.getboolean("database", "check_db_discovery"):
check_db_discovery_with_retries(
retry_num=conf.getint("database", "max_db_discovery_retries"),
initial_retry_wait=conf.getfloat("database",
"db_discovery_initial_wait_time"),
max_retry_wait=conf.getfloat("database",
"db_discovery_max_wait_time"),
)
```
##
airflow-core/src/airflow/utils/db_discovery.py:
##
@@ -0,0 +1,127 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements. See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership. The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+#
Re: [PR] Optionally retry db connection errors related to temporary DNS failures [airflow]
xBis7 commented on code in PR #51586:
URL: https://github.com/apache/airflow/pull/51586#discussion_r2140810147
##
airflow-core/tests/unit/core/test_db_discovery.py:
##
@@ -0,0 +1,164 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements. See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership. The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License. You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied. See the License for the
+# specific language governing permissions and limitations
+# under the License.
+from __future__ import annotations
+
+import contextlib
+import logging
+import os
+import shutil
+import socket
+import time
+
+import pytest
+from sqlalchemy import text
+
+from airflow import settings
+from airflow.utils import db_discovery
+from airflow.utils.db_discovery import DbDiscoveryStatus
+
+log = logging.getLogger(__name__)
+
+
+def dispose_connection_pool():
+"""Dispose any cached sockets so that the next query will force a new
connect."""
+settings.engine.dispose()
+# Wait for SqlAlchemy.
+time.sleep(0.5)
+
+
+def make_db_test_call():
+"""
+Create a session and execute a query.
+
+It will establish a new connection if there isn't one available.
+New connections use DNS lookup.
+"""
+from airflow.utils.session import create_session
+
+with create_session() as session:
+session.execute(text("SELECT 1"))
+
+
+def assert_query_raises_exc(expected_error_msg: str, expected_status: str,
expected_retry_num: int):
+with pytest.raises(socket.gaierror, match=expected_error_msg):
+make_db_test_call()
+
+assert len(db_discovery.db_health_status) == 2
+
+assert db_discovery.db_health_status[0] == expected_status
+assert db_discovery.db_retry_count == expected_retry_num
+
+
[email protected]("postgres")
+class TestDbDiscoveryIntegration:
[email protected]
+def patch_getaddrinfo_for_eai_fail(self, monkeypatch):
+import socket
+
+def always_fail(*args, **kwargs):
+# The error message isn't important, as long as the error code is
EAI_FAIL.
+raise socket.gaierror(socket.EAI_FAIL, "permanent failure")
+
+monkeypatch.setattr(socket, "getaddrinfo", always_fail)
+
+def test_dns_resolution_blip(self):
+os.environ["AIRFLOW__DATABASE__CHECK_DB_DISCOVERY"] = "True"
+
+resolv_file = "/etc/resolv.conf"
+resolv_backup = "/tmp/resolv.conf.bak"
+
+# Back up the original file so that it can later be restored.
+shutil.copy(resolv_file, resolv_backup)
+
+try:
+# Replace the IP with a bad resolver.
+with open(resolv_file, "w", encoding="utf-8") as fh:
+fh.write("nameserver 10.255.255.1\noptions timeout:1
attempts:1 ndots:0\n")
+
+# New connection + DNS lookup.
+dispose_connection_pool()
+assert_query_raises_exc(
+expected_error_msg="Temporary failure in name resolution",
+expected_status=DbDiscoveryStatus.TEMPORARY_ERROR,
+expected_retry_num=3,
+)
+
+finally:
+# Reset the values for the next tests.
+db_discovery.db_health_status = (DbDiscoveryStatus.OK, 0.0)
+db_discovery.db_retry_count = 0
+
+# Restore the original file.
+with contextlib.suppress(Exception):
+shutil.copy(resolv_backup, resolv_file)
+
+def test_permanent_dns_failure(self, patch_getaddrinfo_for_eai_fail):
+os.environ["AIRFLOW__DATABASE__CHECK_DB_DISCOVERY"] = "True"
+
+try:
+# New connection + DNS lookup.
+dispose_connection_pool()
+assert_query_raises_exc(
+expected_error_msg="permanent failure",
+expected_status=DbDiscoveryStatus.PERMANENT_ERROR,
+expected_retry_num=0,
+)
+
+finally:
+# Reset the values for the next tests.
+db_discovery.db_health_status = (DbDiscoveryStatus.OK, 0.0)
+db_discovery.db_retry_count = 0
+
+def test_invalid_hostname_in_config(self):
+os.environ["AIRFLOW__DATABASE__CHECK_DB_DISCOVERY"] = "True"
+os.environ["AIRFLOW__DATABASE__SQL_ALCHEMY_CONN"] = (
+"postgresql+psycopg2://postgres:airflow@invalid/airflow"
+)
+
+try:
+# New connection + DNS lookup.
+dispose_connection_pool()
+assert_query_raises_exc(
+
Re: [PR] Optionally retry db connection errors related to temporary DNS failures [airflow]
xBis7 commented on code in PR #51586:
URL: https://github.com/apache/airflow/pull/51586#discussion_r2140706428
##
airflow-core/tests/unit/core/test_db_discovery.py:
##
@@ -0,0 +1,164 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements. See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership. The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License. You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied. See the License for the
+# specific language governing permissions and limitations
+# under the License.
+from __future__ import annotations
+
+import contextlib
+import logging
+import os
+import shutil
+import socket
+import time
+
+import pytest
+from sqlalchemy import text
+
+from airflow import settings
+from airflow.utils import db_discovery
+from airflow.utils.db_discovery import DbDiscoveryStatus
+
+log = logging.getLogger(__name__)
+
+
+def dispose_connection_pool():
+"""Dispose any cached sockets so that the next query will force a new
connect."""
+settings.engine.dispose()
+# Wait for SqlAlchemy.
+time.sleep(0.5)
+
+
+def make_db_test_call():
+"""
+Create a session and execute a query.
+
+It will establish a new connection if there isn't one available.
+New connections use DNS lookup.
+"""
+from airflow.utils.session import create_session
+
+with create_session() as session:
+session.execute(text("SELECT 1"))
+
+
+def assert_query_raises_exc(expected_error_msg: str, expected_status: str,
expected_retry_num: int):
+with pytest.raises(socket.gaierror, match=expected_error_msg):
+make_db_test_call()
+
+assert len(db_discovery.db_health_status) == 2
+
+assert db_discovery.db_health_status[0] == expected_status
+assert db_discovery.db_retry_count == expected_retry_num
+
+
[email protected]("postgres")
+class TestDbDiscoveryIntegration:
[email protected]
+def patch_getaddrinfo_for_eai_fail(self, monkeypatch):
+import socket
+
+def always_fail(*args, **kwargs):
+# The error message isn't important, as long as the error code is
EAI_FAIL.
+raise socket.gaierror(socket.EAI_FAIL, "permanent failure")
+
+monkeypatch.setattr(socket, "getaddrinfo", always_fail)
+
+def test_dns_resolution_blip(self):
+os.environ["AIRFLOW__DATABASE__CHECK_DB_DISCOVERY"] = "True"
+
+resolv_file = "/etc/resolv.conf"
+resolv_backup = "/tmp/resolv.conf.bak"
+
+# Back up the original file so that it can later be restored.
+shutil.copy(resolv_file, resolv_backup)
+
+try:
+# Replace the IP with a bad resolver.
+with open(resolv_file, "w", encoding="utf-8") as fh:
+fh.write("nameserver 10.255.255.1\noptions timeout:1
attempts:1 ndots:0\n")
+
+# New connection + DNS lookup.
+dispose_connection_pool()
+assert_query_raises_exc(
+expected_error_msg="Temporary failure in name resolution",
+expected_status=DbDiscoveryStatus.TEMPORARY_ERROR,
+expected_retry_num=3,
+)
+
+finally:
+# Reset the values for the next tests.
+db_discovery.db_health_status = (DbDiscoveryStatus.OK, 0.0)
+db_discovery.db_retry_count = 0
+
+# Restore the original file.
+with contextlib.suppress(Exception):
+shutil.copy(resolv_backup, resolv_file)
+
+def test_permanent_dns_failure(self, patch_getaddrinfo_for_eai_fail):
+os.environ["AIRFLOW__DATABASE__CHECK_DB_DISCOVERY"] = "True"
+
+try:
+# New connection + DNS lookup.
+dispose_connection_pool()
+assert_query_raises_exc(
+expected_error_msg="permanent failure",
+expected_status=DbDiscoveryStatus.PERMANENT_ERROR,
+expected_retry_num=0,
+)
+
+finally:
+# Reset the values for the next tests.
+db_discovery.db_health_status = (DbDiscoveryStatus.OK, 0.0)
+db_discovery.db_retry_count = 0
+
+def test_invalid_hostname_in_config(self):
+os.environ["AIRFLOW__DATABASE__CHECK_DB_DISCOVERY"] = "True"
+os.environ["AIRFLOW__DATABASE__SQL_ALCHEMY_CONN"] = (
+"postgresql+psycopg2://postgres:airflow@invalid/airflow"
+)
Review Comment:
Done.
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Re: [PR] Optionally retry db connection errors related to temporary DNS failures [airflow]
xBis7 commented on PR #51586: URL: https://github.com/apache/airflow/pull/51586#issuecomment-2963769319 @jason810496 I've addressed all of your comments. Can you take another look? -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
Re: [PR] Optionally retry db connection errors related to temporary DNS failures [airflow]
xBis7 commented on code in PR #51586: URL: https://github.com/apache/airflow/pull/51586#discussion_r2140669653 ## airflow-core/tests/unit/utils/test_db_discovery_status.py: ## @@ -0,0 +1,71 @@ +# +# Licensed to the Apache Software Foundation (ASF) under one +# or more contributor license agreements. See the NOTICE file +# distributed with this work for additional information +# regarding copyright ownership. The ASF licenses this file +# to you under the Apache License, Version 2.0 (the +# "License"); you may not use this file except in compliance +# with the License. You may obtain a copy of the License at +# +# http://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, +# software distributed under the License is distributed on an +# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY +# KIND, either express or implied. See the License for the +# specific language governing permissions and limitations +# under the License. +from __future__ import annotations + +import socket + +import pytest + +from airflow.utils import db_discovery +from airflow.utils.db_discovery import DbDiscoveryStatus + + +class TestDbDiscoveryStatus: [email protected]( +"retry, expected_sleep_time", +[ +pytest.param(0, 0.5, id="attempt-1"), +pytest.param(1, 1, id="attempt-2"), +pytest.param(2, 2, id="attempt-3"), +pytest.param(3, 4, id="attempt-4"), +pytest.param(4, 8, id="attempt-5"), +pytest.param(5, 15, id="attempt-6"), +pytest.param(6, 15, id="attempt-7"), +], +) +def test_get_sleep_time(self, retry: int, expected_sleep_time: float): +sleep = db_discovery.get_sleep_time(retry, 0.5, 15) +assert sleep == expected_sleep_time + [email protected]( +"error_code, expected_status", +[ +(socket.EAI_FAIL, DbDiscoveryStatus.PERMANENT_ERROR), +(socket.EAI_AGAIN, DbDiscoveryStatus.TEMPORARY_ERROR), +(socket.EAI_NONAME, DbDiscoveryStatus.UNKNOWN_HOSTNAME), +(socket.EAI_SYSTEM, DbDiscoveryStatus.UNKNOWN_ERROR), +], +) +def test_check_dns_resolution_with_retries(self, monkeypatch, error_code, expected_status): +def raise_exc(*args, **kwargs): +# The error message isn't important because the validation is based on the error code. +raise socket.gaierror(error_code, "patched failure") + +monkeypatch.setattr(socket, "getaddrinfo", raise_exc) Review Comment: Done. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
Re: [PR] Optionally retry db connection errors related to temporary DNS failures [airflow]
xBis7 commented on code in PR #51586:
URL: https://github.com/apache/airflow/pull/51586#discussion_r2140560095
##
airflow-core/src/airflow/utils/db_discovery.py:
##
@@ -0,0 +1,117 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements. See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership. The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License. You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied. See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+from __future__ import annotations
+
+import logging
+import socket
+import time
+
+from sqlalchemy.engine.url import make_url
+
+from airflow.configuration import conf
+
+logger = logging.getLogger(__name__)
+
+
+class DbDiscoveryStatus:
+"""Enum with the return value for `check_db_discovery_if_needed()`."""
+
+# The hostname resolves.
+OK = "ok"
+# There has been some temporary DNS lookup blip and the connection will
probably recover.
+# Causes: a dns timeout or a temporary network issue.
+TEMPORARY_ERROR = "dns_temporary_failure"
+# Unknown hostname or service, this is permanent and the connection can't
be recovered.
+# Causes: a cmd or config typo, a hostname that doesn't exist.
+UNKNOWN_HOSTNAME = "unknown_hostname"
+# Unknown hostname or service, this is permanent and the connection can't
be recovered.
+# Causes: Failed DNS server or config typo.
+PERMANENT_ERROR = "dns_permanent_failure"
+# Some other error.
+UNKNOWN_ERROR = "unknown_error"
+
+
+# db status - how long ago it was retrieved
+db_health_status: tuple[str, float] = (DbDiscoveryStatus.OK, 0.0)
+
+# TODO: For now, this is used for testing
+# but it can also be used to add stats.
+db_retry_count: int = 0
+
+
+def get_sleep_time(retry_attempt: int, initial_wait: float, max_wait: float)
-> float:
+return min(initial_wait * (2**retry_attempt), max_wait)
+
+
+def _retry_exponential_backoff(retry_attempt: int, initial_wait: float,
max_wait: float) -> None:
+sleep_time = get_sleep_time(retry_attempt, initial_wait, max_wait)
+unit_str = "second" if sleep_time == float(1) else "seconds"
+logger.info("Sleeping for %.2f %s.", sleep_time, unit_str)
+time.sleep(sleep_time)
Review Comment:
I updated it to use tenacity.
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Re: [PR] Optionally retry db connection errors related to temporary DNS failures [airflow]
xBis7 commented on PR #51586: URL: https://github.com/apache/airflow/pull/51586#issuecomment-2963109894 @jason810496 Thank you for the review, I'll look into your comments! -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
Re: [PR] Optionally retry db connection errors related to temporary DNS failures [airflow]
xBis7 commented on code in PR #51586: URL: https://github.com/apache/airflow/pull/51586#discussion_r2140402145 ## airflow-core/src/airflow/config_templates/config.yml: ## @@ -679,6 +679,39 @@ database: type: integer example: ~ default: "1" +check_db_discovery: + description: | +Whether to check the db discovery before creating a new session. +If enabled, the dns lookup to the db hostname will be checked with retries. +Accepts ``True`` or ``False``. + version_added: 3.1.0 + type: string Review Comment: You are right, nice catch! -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
Re: [PR] Optionally retry db connection errors related to temporary DNS failures [airflow]
jason810496 commented on code in PR #51586:
URL: https://github.com/apache/airflow/pull/51586#discussion_r2140285753
##
airflow-core/src/airflow/utils/db_discovery.py:
##
@@ -0,0 +1,117 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements. See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership. The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License. You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied. See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+from __future__ import annotations
+
+import logging
+import socket
+import time
+
+from sqlalchemy.engine.url import make_url
+
+from airflow.configuration import conf
+
+logger = logging.getLogger(__name__)
+
+
+class DbDiscoveryStatus:
+"""Enum with the return value for `check_db_discovery_if_needed()`."""
+
+# The hostname resolves.
+OK = "ok"
+# There has been some temporary DNS lookup blip and the connection will
probably recover.
+# Causes: a dns timeout or a temporary network issue.
+TEMPORARY_ERROR = "dns_temporary_failure"
+# Unknown hostname or service, this is permanent and the connection can't
be recovered.
+# Causes: a cmd or config typo, a hostname that doesn't exist.
+UNKNOWN_HOSTNAME = "unknown_hostname"
+# Unknown hostname or service, this is permanent and the connection can't
be recovered.
+# Causes: Failed DNS server or config typo.
+PERMANENT_ERROR = "dns_permanent_failure"
+# Some other error.
+UNKNOWN_ERROR = "unknown_error"
+
+
+# db status - how long ago it was retrieved
+db_health_status: tuple[str, float] = (DbDiscoveryStatus.OK, 0.0)
+
+# TODO: For now, this is used for testing
+# but it can also be used to add stats.
+db_retry_count: int = 0
+
+
+def get_sleep_time(retry_attempt: int, initial_wait: float, max_wait: float)
-> float:
+return min(initial_wait * (2**retry_attempt), max_wait)
+
+
+def _retry_exponential_backoff(retry_attempt: int, initial_wait: float,
max_wait: float) -> None:
+sleep_time = get_sleep_time(retry_attempt, initial_wait, max_wait)
+unit_str = "second" if sleep_time == float(1) else "seconds"
+logger.info("Sleeping for %.2f %s.", sleep_time, unit_str)
+time.sleep(sleep_time)
Review Comment:
IMO, we can leverage `tenacity` for retrying, as `tenacity` is already used
in airflow core for a while.
e.g.`run_with_db_retries`
https://github.com/apache/airflow/blob/c4d7edb250dd988037c3e0eb024dbb77ab14c165/airflow-core/src/airflow/utils/retries.py#L33-L48
##
airflow-core/src/airflow/config_templates/config.yml:
##
@@ -679,6 +679,39 @@ database:
type: integer
example: ~
default: "1"
+check_db_discovery:
+ description: |
+Whether to check the db discovery before creating a new session.
+If enabled, the dns lookup to the db hostname will be checked with
retries.
+Accepts ``True`` or ``False``.
+ version_added: 3.1.0
+ type: string
Review Comment:
```suggestion
type: boolean
```
##
airflow-core/tests/unit/utils/test_db_discovery_status.py:
##
@@ -0,0 +1,71 @@
+#
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements. See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership. The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License. You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied. See the License for the
+# specific language governing permissions and limitations
+# under the License.
+from __future__ import annotations
+
+import socket
+
+import pytest
+
+from airflow.utils import db_discovery
+from airflow.utils.db_discovery import DbDiscoveryStatus
+
+
+class TestDbDiscoveryStatus:
[email protected](
+"retry, expected_sleep_time",
+[
+pytest.param(0, 0.5, id="attempt-1"),
+pytest.param(1, 1, id="attempt-2"),
+pytest.param(2, 2, id="attempt-3"),
+pytest.param(3, 4, id="attempt-4"),
+pytest.param(4, 8, id="
