問題描述
服務器鏡像有寶塔面板 + Python2，用yum和pip3安裝Python3 + Flask + Gunicorn后，寶塔面板打不開了。報錯如下：
Starting Bt-Panel..........failed
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[Traceback (most recent call last):
File "/usr/local/lib/python3.6/site-packages/gunicorn/util.py", line 135, in load_class
mod = import_module('.'.join(components))
File "/usr/local/lib/python3.6/importlib/__init__.py", line 126, in import_module
return _bootstrap._gcd_import(name[level:], package, level)
File "<frozen importlib._bootstrap>", line 994, in _gcd_import
File "<frozen importlib._bootstrap>", line 971, in _find_and_load
File "<frozen importlib._bootstrap>", line 941, in _find_and_load_unlocked
File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
File "<frozen importlib._bootstrap>", line 994, in _gcd_import
File "<frozen importlib._bootstrap>", line 971, in _find_and_load
File "<frozen importlib._bootstrap>", line 941, in _find_and_load_unlocked
File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
File "<frozen importlib._bootstrap>", line 994, in _gcd_import
File "<frozen importlib._bootstrap>", line 971, in _find_and_load
File "<frozen importlib._bootstrap>", line 953, in _find_and_load_unlocked
ModuleNotFoundError: No module named 'geventwebsocket'
]
------------------------------------------------------
Error: BT-Panel service startup failed.
done
報錯早就刷上去了，找不回來，這段照搬別人的[^引用1]，因為看着差不了多少。
其實我的情況跟引用1差不多，但是就是最后一步依然報錯。
修復
修復目標是讓寶塔面板和Python3都能正常使用。
01 | 卸載python3+修復軟鏈接
聽說寶塔面板使用Python2編寫，直接安裝Python3的話會出現問題。[^引用4]
卸載Python3之后依然報如上的錯，路徑居然依然是python3.6，猜測可能是軟鏈接接錯了。
[root@server bin]# ll | grep python
lrwxrwxrwx 1 root root 7 Jul 11 2019 python -> python2
lrwxrwxrwx 1 root root 9 Jul 11 2019 python2 -> python2.7
-rwxr-xr-x 1 root root 7216 Jun 21 2019 python2.7
-rwxr-xr-x 1 root root 1835 Jun 21 2019 python2.7-config
lrwxrwxrwx 1 root root 16 Jul 11 2019 python2-config -> python2.7-config
lrwxrwxrwx 1 root root 14 Jul 11 2019 python-config -> python2-config
雖然看着好像沒錯，但還是按照官方論壇里的方法[^引用2]操作一遍。
[root@server bin]# ll | grep python
lrwxrwxrwx 1 root root 18 Mar 2 17:01 python -> /usr/bin/python2.7
-rwxr-xr-x 1 root root 7216 Jun 21 2019 python2.7
-rwxr-xr-x 1 root root 1835 Jun 21 2019 python2.7-config
lrwxrwxrwx 1 root root 16 Jul 11 2019 python2-config -> python2.7-config
lrwxrwxrwx 1 root root 14 Jul 11 2019 python-config -> python2-config
02 | 再次啟動，路徑正常了但仍報錯
Error: Not a string: ['0.0.0.0:8888\n']
.........failed
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from BTPanel import app,sys,public
File "/usr/lib64/python2.7/site-packages/gevent/builtins.py", line 96, in __import__
result = _import(*args, **kwargs)
File "/www/server/panel/BTPanel/__init__.py", line 28, in <module>
from flask_sockets import Sockets
File "/usr/lib64/python2.7/site-packages/gevent/builtins.py", line 96, in __import__
result = _import(*args, **kwargs)
File "class/flask_sockets.py", line 11, in <module>
from geventwebsocket.gunicorn.workers import GeventWebSocketWorker as Worker
File "/usr/lib64/python2.7/site-packages/gevent/builtins.py", line 96, in __import__
result = _import(*args, **kwargs)
File "/usr/lib/python2.7/site-packages/geventwebsocket/gunicorn/workers.py", line 2, in <module>
from gunicorn.workers.ggevent import GeventPyWSGIWorker
File "/usr/lib64/python2.7/site-packages/gevent/builtins.py", line 96, in __import__
result = _import(*args, **kwargs)
File "/usr/lib/python2.7/site-packages/gunicorn/workers/ggevent.py", line 39, in <module>
class GeventWorker(AsyncWorker):
File "/usr/lib/python2.7/site-packages/gunicorn/workers/ggevent.py", line 90, in GeventWorker
if hasattr(gevent.core, 'dns_shutdown'):
AttributeError: 'module' object has no attribute 'core'
------------------------------------------------------
Error: BT-Panel service startup failed.
03 | 根據引用1重裝gunicorn
報錯
ERROR: Package 'gunicorn' requires a different Python: 2.7.5 not in '>=3.4'
不明白為什么使用python2的pip安裝會出現這個錯誤，但還是找到了解決方法[^引用3]：
[root@server bin]# pip install gunicorn==999
[root@server bin]# pip install gunicorn==0.14.1
先指定安裝一個不存在的版本999，回車后會提示可以安裝的版本，然后隨便挑一個安裝就好了，我挑了偏中間的0.14.1安裝。
04 | 重裝gunicorn后報錯依舊
到這步就沒轍了，甚至更新過寶塔面板也依然沒用。耗了很久，心態爆炸。
看了很多資料，看見有人去分析過寶塔面板的源碼去糾錯，於是我也找到了寶塔面板的開源地址，無意間看到源代碼根目錄下有一份requirements.txt（pip freeze導出的需要的庫的名單和版本，見引用5），發現里面根本就沒有gunicorn，人家用的是gevent！
嗯，心態爆炸了。
卸載掉gunicorn，下一刻就啟動起來了……
簡單測試過后，一點貓餅都沒有。