I'm quite new to using Tornado Web as a web server, and am having a little difficulty keeping it running. I normally use Django and Nginx, and am used to start/stop/restarting the server. However with Tornado I'm having trouble telling it to "run" without directly executing my main python file for the site, ie "python ~/path/to/server.py".
I'm sure I'm getting this completely wrong - is there a way of 'bootstrapping' my script so that when Nginx starts, Tornado starts?
Any help would be appreciated!
A better way to do it is using supervisord as it is also written in python
No, there is not a way to have nginx spawn your tornado instance.
Typically you would use an external framework like daemontools or a system init script to run the tornado process.
Related
I don't know if you know about this website (as I can't read your mind), but openshift is it. It is a web-hosting website. You can use python or whatever for server-side.
The problem is openshift is looking for a wsgi application. But I am using websockets with tornado so I can't use wsgi. How does I make openshift not look for wsgi, but any type of applicaiton? Or does the website only support that.
The error message I am seeing is:
'wsgi.py' does not contain WSGI application 'application'
I really need a server with websockets, I am planning on creating a multiplayer online game with javascript using websockets.
Thanks for the help, everyone.
Put your application in app.py. This will allow you to run whatever you want. See:
http://blog.dscpl.com.au/2015/08/running-async-web-applications-under.html
I was wondering what is the advantages of mod_wsgi. For most python web framework, I can launch (daemon) the application by python directly and serve it in a port. Then when shall I use mod_wsgi?
Since I answered your other question regarding Flask, I assume you are referring to using Flask's development server. The problem with that is it is single threaded.
Using mod_wsgi, you would be running behind apache, which will do process forking and allow for multiple simultaneous requests to be handled.
There are other options as well. Depending on your particular use case I would consider using eventlet's wsgi server.
I want to have simple program in python that can process different requests (POST, GET, MULTIPART-FORMDATA). I don't want to use a complete framework.
I basically need to be able to get GET and POST params - probably (but not necessarily) in a way similar to PHP. To get some other SERVER variables like REQUEST_URI, QUERY, etc.
I have installed nginx successfully, but I've failed to find a good example on how to do the rest. So a simple tutorial or any directions and ideas on how to setup nginx to run certain python process for certain virtual host would be most welcome!
Although you can make Python run a webserver by itself with wsgiref, I would recommend using one of the many Python webservers and/or web frameworks around. For pure and simple Python webhosting we have several options available:
gunicorn
tornado
twisted
uwsgi
cherrypy
If you're looking for more features you can look at some web frameworks:
werkzeug
flask
masonite
cherrypy (yes, cherrypy is both a webserver and a framework)
django (for completeness, I know that was not the purpose of the question)
You should look into using Flask -- it's an extremely lightweight interface to a WSGI server (werkzeug) which also includes a templating library, should you ever want to use one. But you can totally ignore it if you'd like.
You can use thttpd. It is a lightweight wsgi server for running cgi scripts. It works well with nginx. How to setup thttpd with Nginx is detailed here: http://nginxlibrary.com/running-cgi-scripts-using-thttpd/
All the same you must use wsgi server, as nginx does not support fully this protocol.
Ubuntu 11.10, Python 2.6. Background: I have an existing Python app that is using Twisted to sit in a loop and wait for RESTful commands to come in. So the app starts up, kicks off threads that do various things, and main sets up callbacks for Twisted, then calls Twisted.reactor.run(), which blocks forever. When a request comes in, the appropriate handler is called, stuff happens, a reply is sent back.
My job is now to remove Twisted because management has decided they don't like it. We're moving to Apache as our web server.
Using the documentation, I have successfully installed and configured Apache2.0 to serve web pages. I also installed mod_wsgi, and was able to configure it and Apache to execute arbitrary Python code when a request comes in. So I'm good on that side.
What I'm missing is how to connect my Python application to the Apache/mod_wsgi bits, since the application needs to be persistent and always running. It was suggested that I open a pipe between my wsgi script and my main application, and serialize the requests that way. But it seems like this is something that should already be out there, I just don't know enough to know what to search for.
Any pushes in the right direction are greatly appreciated.
Further edit for clarity: I'm not making a webserver. The application in question is a host app that is running on a virtual machine. It happens to be controlled by a RESTful interface via HTTP. So all it needs to do is be able to listen for incoming commands and reply to them.
mod_wsgi may not be the proper tool for this job, which is fine, I just don't know what is.
Does the daemon mode of mod_wsgi offer enough persistence in your case? Or if you want to run the main process separately from Apache, how about mod_fastcgi? Maybe running Apache as a reverse proxy could be an option too.
It was suggested that I open a pipe between my wsgi script and my main application, and serialize the requests that way.
That's what multiprocessing queues are for.
http://docs.python.org/library/multiprocessing.html
http://docs.python.org/library/multiprocessing.html#pipes-and-queues
You'll be even happier if you start using Celery.
Celery will allow you to "remove Twisted because management has decided they don't like it."
However. Switch to celery means that things like "So the app starts up, kicks off threads that do various things, and main sets up callbacks for Twisted, then calls Twisted.reactor.run(), which blocks forever" all have to be completely rethought. Instead of some main polling loop, you now have multiple, independent processes that are coordinated by celery.
What you'll find is all the housekeeping in your application -- all the coordination among threads -- the callbacks -- all that -- will go away. You'll be left with a few Python scripts that do the "real work" and Celery to manage the distributed task queue.
Is it possible to run a script each time the dev server starts? Also at each deploy to google?
I want the application to fill the database based on what some methods returns.
Is there any way to do this?
..fredrik
I use appengine python with the django helper. As far as I know you cannot hook anything on the deploy, but you could put a call to check if you need to do your setup in the main function of main.py. This is how the helper initializes itself on the first request. I haven't looked at webapp in a while, but I assume main.py acts in a similar fashion for that framework.
Be aware that main is run on the first request, not when you first deploy. It will also happen if appengine starts up a new instance to handle load, or if all instances were stopped because of inactivity. So make sure you check to see if you need to do your initialization and then only do it if needed.
You can do this by writing a script in your favorite scripting language that performs the actions that you desire and then runs the dev server or runs appcfg.py update.
Try to make wrapper around the server runner and script that run deployment. So you will be able to run custom code when you need.
Warmup Requests in combination with min_idle_instances will probably work in your deploy usecase.