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How to Enable CloudLinux Python and Ruby Selector (alt-mod_passenger) for LSWS
To enable Python or Ruby on a shared hosting environment instead of in a dedicated VPS environment (such as cpanel, DirectAdmin etc), CloudLinux Python and Ruby Selector is recommended. If it is not for a shared hosting environment, you can refer to our archive section for LSWS native setup.
The Python and Ruby Selector allows end users to select the specific version of Python or Ruby they need.
LiteSpeed supports the Apache mod_passenger
configuration generated through CloudLinux selectors (LiteSpeed doesn't support most of the mod_passenger apache rules and only support a few of the long list. Please check here for LiteSpeed supported Mod_Passenger rules). However, behind the scenes, LiteSpeed's is a completely different implementation to Apache's.
Requirements
- LiteSpeed Web Server 5.2+
- CloudLinux
Steps to Enable Python and Ruby Selector
- Make sure Python and Ruby Selector works properly under Apache (follow CloudLinux instructions to install and configure).
- Test a Ruby or Python application with Apache and ensure it is running OK.
- Run script to install required ruby/python lsapi modules:
/usr/local/lsws/admin/misc/enable_ruby_python_selector.sh
- Switch to LiteSpeed and try a ruby/python app
Restart the Python and Ruby Application
There are two ways to restart the Python and Ruby application: through the cPanel CloudLinux Python Application Manager, or by touching the <app_root_dir>/tmp/restart.txt
file.
For example, if a Python application is located at /home/user1/mypythonapp
the command would be:
touch /home/user1/mypythonapp/tmp/restart.txt
This will tell the server to restart the application.
NOTE: If you are restarting the Python app by touching <app_root_dir>/tmp/restart.txt
, and the file already exists, you must still touch
it to restart the app.
Troubleshooting
The application does not work properly
If your application does not work properly, you can try two simple steps to check if the application has been setup properly:
- If possible, switch back to Apache temporarily to verify if the application works properly under Apache.
- Check if any error has been logged into
<APP_ROOT_DIR>/stderr.log
. If it has, fix the error and try again.
For example:
A Python application writes an error to stderr.log under the application root directory, /home/user1/dingodossier/mbntp/stderr.log
:
Traceback (most recent call last): File "/home/user1/dingodossier/mbntp/passenger_wsgi.py", line 8, in <module> wsgi = imp.load_source('wsgi', 'mbntp/wsgi.py') File "/home/user1/virtualenv/dingodossier_mbntp/3.4/lib64/python3.4/imp.py", line 171, in load_source module = methods.load() File "<frozen importlib._bootstrap>", line 1220, in load File "<frozen importlib._bootstrap>", line 1200, in _load_unlocked File "<frozen importlib._bootstrap>", line 1129, in _exec File "<frozen importlib._bootstrap>", line 1471, in exec_module File "<frozen importlib._bootstrap>", line 321, in _call_with_frames_removed File "mbntp/wsgi.py", line 10, in <module> from django.core.wsgi import get_wsgi_application ImportError: No module named 'django'
This indicates Django was not properly set up for the application.
The application will not restart
If touch <app_root_dir>/tmp/restart.txt
or the CloudLinux Python manager fail to restart the Python application, there may be some old lswsgi processes in the way. Use the ps
command to verify:
ps -ef | grep pythontest
pythont+ 508045 1 0 Aug13 ? 00:01:23 /opt/alt/python37/bin/lswsgi -m /home/pythontest/pyapp1/passenger_wsgi.py pythont+ 890556 1 0 Jul31 ? 00:05:34 /opt/alt/python37/bin/lswsgi -m /home/pythontest/pyapp1/passenger_wsgi.py pythont+ 1470047 1 0 Jul19 ? 00:10:36 /opt/alt/python37/bin/lswsgi -m /home/pythontest/pyapp1/passenger_wsgi.py pythont+ 1900598 1866381 0 15:14 ? 00:00:00 /opt/alt/python37/bin/lswsgi -m /home/pythontest/pyapp1/passenger_wsgi.py root 1902042 1898738 0 15:22 pts/2 00:00:00 grep --color=auto pythontest pythont+ 2741844 1 0 Jul23 ? 00:08:41 /opt/alt/python37/bin/lswsgi -m /home/pythontest/pyapp1/passenger_wsgi.py
Even though you may have restarted the latest lswsgi process, the old running processes can cause restart issues. You may find, even if you switch to Apache, that these processes remain. The best way to deal with them is to log into the user via SSH and manually kill the processes.