ERROR sqlalchemy.exc.InvalidRequestError: No such event 'pending_to_persistent' for target '<class 'sqlalchemy.orm.session.Session'>'

OpenStack-Controller 节点 neutron 相关服务重启失败

排查报错如下

[root@controller ~]# su -g neutron -c '/usr/bin/neutron-server --config-file /usr/share/neutron/neutron-dist.conf --config-dir /usr/share/neutron/server --config-file /etc/neutron/neutron.conf --config-file /etc/neutron/plugin.ini --config-dir /etc/neutron/conf.d/common --config-dir /etc/neutron/conf.d/neutron-server --log-file /var/log/neutron/server.log'
Traceback (most recent call last):
  File "/usr/bin/neutron-server", line 6, in <module>
    from neutron.cmd.eventlet.server import main
  File "/usr/lib/python2.7/site-packages/neutron/cmd/eventlet/server/__init__.py", line 13, in <module>
    from neutron import server
  File "/usr/lib/python2.7/site-packages/neutron/server/__init__.py", line 25, in <module>
    from neutron.common import config
  File "/usr/lib/python2.7/site-packages/neutron/common/config.py", line 23, in <module>
    from neutron_lib.api import validators
  File "/usr/lib/python2.7/site-packages/neutron_lib/__init__.py", line 15, in <module>
    from neutron_lib.db import api  # noqa
  File "/usr/lib/python2.7/site-packages/neutron_lib/db/api.py", line 420, in <module>
    @event.listens_for(orm.session.Session, "pending_to_persistent")
  File "/usr/lib64/python2.7/site-packages/sqlalchemy/event/api.py", line 124, in decorate
    listen(target, identifier, fn, *args, **kw)
  File "/usr/lib64/python2.7/site-packages/sqlalchemy/event/api.py", line 89, in listen
    _event_key(target, identifier, fn).listen(*args, **kw)
  File "/usr/lib64/python2.7/site-packages/sqlalchemy/event/api.py", line 28, in _event_key
    (identifier, target))
sqlalchemy.exc.InvalidRequestError: No such event 'pending_to_persistent' for target '<class 'sqlalchemy.orm.session.Session'>'

...继续

在sqlalchemy官方文档, 找到了 pending_to_persistent 定义

https://docs.sqlalchemy.org/en/14/orm/events.html?highlight=pending_to_persistent#sqlalchemy.orm.SessionEvents.pending_to_persistent

发现: 'pending_to_persistent' New in version 1.1.

排查服务器

[root@controller ~]# pip show sqlalchemy
    ---
    Metadata-Version: 1.1
    Name: SQLAlchemy
    Version: 1.0.19
    Summary: Database Abstraction Library
    Home-page: http://www.sqlalchemy.org
    Author: Mike Bayer
    Author-email: mike_mp@zzzcomputing.com
    License: MIT License
    Location: /usr/lib64/python2.7/site-packages
    Requires: 
    Classifiers:
    Development Status :: 5 - Production/Stable
    Intended Audience :: Developers
    License :: OSI Approved :: MIT License
    Programming Language :: Python
    Programming Language :: Python :: 3
    Programming Language :: Python :: Implementation :: CPython
    Programming Language :: Python :: Implementation :: Jython
    Programming Language :: Python :: Implementation :: PyPy
    Topic :: Database :: Front-Ends
    Operating System :: OS Independent


虚拟机里装了很多乱起八糟的依赖, 估计是哪个包导致 sqlalchemy 版本降了, neutron 被殃及了

解决方案

确定 sqlalchemy 版本范围
    官方依赖版本要求如下

    https://github.com/openstack/neutron/blob/stable/train/requirements.txt

    ...
    SQLAlchemy>=1.2.0 # MIT
    ...


升级 sqlalchemy
    [root@controller ~]# pip install sqlalchemy==1.3.8
    Collecting sqlalchemy==1.3.8
    Downloading https://pypi.tuna.tsinghua.edu.cn/packages/fc/49/82d64d705ced344ba458197dadab30cfa745f9650ee22260ac2b275d288c/SQLAlchemy-1.3.8.tar.gz (5.9MB)
        100% |████████████████████████████████| 5.9MB 2.0MB/s 
    Installing collected packages: sqlalchemy
    Found existing installation: SQLAlchemy 1.0.19
        Uninstalling SQLAlchemy-1.0.19:
        Successfully uninstalled SQLAlchemy-1.0.19
    Running setup.py install for sqlalchemy ... done
    Successfully installed sqlalchemy-1.3.8


重启服务
    [root@controller ~]# systemctl restart neutron-server.service neutron-linuxbridge-agent.service neutron-dhcp-agent.service neutron-metadata-agent.service
    [root@controller ~]# systemctl restart neutron-l3-agent.service


验证
    [root@controller ~]# systemctl -a | grep neutron
    neutron-dhcp-agent.service          loaded    active   running   OpenStack Neutron DHCP Agent
    neutron-l3-agent.service            loaded    active   running   OpenStack Neutron Layer 3 Agent
    neutron-linuxbridge-agent.service   loaded    active   running   OpenStack Neutron Linux Bridge Agent
    neutron-metadata-agent.service      loaded    active   running   OpenStack Neutron Metadata Agent
    neutron-server.service              loaded    active   running   OpenStack Neutron Server


ok