I have been learning Flask by making a little website and using the built in flask server that runs with python. I have a page where you press a button, and it flashes a message using the flash system inside of flask. These flashes work fine when I am using the built in flask server on my windows machine. However, I have deployed the website to a Linux server, using uWSGI which goes through Nginx. My issue is that when I access this server, the flashes don't work. Most things like loading pages work fine on both servers, but flashing is broken. I don't see any error messages from uWSGI's logs.
The code I am using for the flash is implemented as follows:
flash("Made new post.")
return redirect(url_for("posts"))
The redirect takes me to the correct page, and if I run a print() statement before the redirect the statements are clearly being reached, the flash just doesn't do anything.
The main other issue I am running into is with sessions and trying to store session variables. Nothing happens when I try to do this either. (but it works on my personal machine)
Any ideas why this might be, or at least a way to get an error message from uWSGI?
To properly set cookies (cookies are what make message Flashing work), both nginx and the Flask application need to agree on the server name.
So make sure your server_name in nginx.conf matches SERVER_NAME (or
SESSION_COOKIE_DOMAIN, if set) in your flask configuration.
There are also limits enforced by nginx on the size of cookies, but this should only be a problem if your flashed messages are really large.
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I have been working on a flask application and it has been working just fine. however, for a couple of hours now, i have not been able to run my application on the web. After running the script on command line as usual, i would copy the ip address to my browser in order to display its content but will not respond anymore. I have tried changing port, and other troubleshooting i suppose should work but has still not been able to get it fixed. Any assistance is highly appreciated.
The error message is " this site can not be reached" when is actually running on the server in command line.
I occasionally have a problem with flask socket-io freezing, and I have no clue how to fix it.
My client connects to my socket-io server and performs some chat sessions. It works nicely. But for some reason, sometimes from the client side, there is some call that blocks the whole server (The server is stuck in the process, and all other calls are frozen). What is strange is that the server can be blocked as long as the client side app is not totally shutdown.This is an ios-app / web page, and I must totally close the app or the safari page. Closing the socket itself, and even deallocating it doesn't resolve the problem. When the app is in the background, the sockets are closed and deallocated but the problem persists.
This is a small server, and it deals with both html pages and the socket-server so I have no idea if it is the socket itself or the html that blocks the process. But each time the server was freezing, the log showed some socket calls.
Here is how I configured my server:
socketio = SocketIO(app, ping_timeout=5)
socketio.run(app, host='0.0.0.0', port=5001, debug=True, ssl_context=context)
So my question is:
What can freeze the server (this seems to happen when I leave the app or web-site open for a long time while doing nothing). If I use the services normally the server never freezes. And how I can prevent it from happening (Even if I don't know what causing this, is there a way to blindly stop my server from being stuck at a call?
Thanks you for the answers
According to your comment above, you are using the Flask development web server, without the help of an asynchronous framework such as eventlet or gevent. Besides this option being highly inefficient, you should know that this web server is not battle tested, it is meant for short lived tests during development. I'm not sure it is able to run for very long, specially under the unusual conditions Flask-SocketIO puts it through, which regular Flask apps do not exercise. I think it is quite possible that you are hitting some obscure bug in Werkzeug that causes it to hang.
My recommendation is that you install eventlet and try again. All you need to do is pip install eventlet, and assuming you are not passing an explicit async_mode argument, then just by installing this package Flask-SocketIO should configure itself to use it.
I would also remove the explicit timeout setting. In almost all cases, the defaults are sufficient to maintain a healthy connection.
I was tasked with making some changes to a Django application. I've never worked with Django and I am having trouble figuring out how to get my changes to compile and be available online.
What I know so far is that the application is currently available online. netstat tells me that httpd is listening on port 80. My change was made in the myapp/views.py file.
I tried to restart httpd using services httpd restart but my changes did not take effect. I've been looking into the issue a bit an I believe that I need to run a command along the lines of:
I tried calling python manage.py runserver MY.IP.AD.DR:8000 and I get:
python manage.py runserver 129.64.101.14:8000
Validating models...
0 errors found
Django version 1.4.1, using settings 'cutsheets.settings'
Development server is running at http://MY.IP.AD.DR:8000/
Quit the server with CONTROL-C.
Nice that no errors are found but when I navigate to http://MY.IP.AD.DR:8000/ I just get a "Unable to connect" message from my browser. I tried with port 81 too and had the same problem.
Without knowing exactly how your application is set up, I can't really say exactly how to solve this problem.
I can tell you that it's quite common to use two web servers with Django - one handles the static content, and reverse proxies everything else to a different port where the Django app is listening. Restarting the normal HTTP daemon therefore wouldn't affect the Django app, so you need to restart the one handling the Django app. Until you restart it, the prior version of the code will be running.
I generally use Nginx as my static server and Gunicorn with the Django app, with Supervisor used to run Gunicorn, and this is a common setup. I recommend you take a look at the config for the main web server to see if it forwards anything to another port. If so, you need to see what server is running on that port and restart it.
Also, is there a Fabric configuration (fabfile.py)? A lot of people use Fabric to automate Django deployments, and if there is one then there may be a command already defined for deploying.
So, probably a dumb question, but I am beginning to learn all this so your feedback will be valuable for me.
The question is: In flask documentation it says start the flask server by entering the command 'python hello.py' and I do it successfully to see the output on localhost:5000. Now, I have a shared hosting plan and if I upload this file over there will i need to initiate the server over there as well like this? If so, when I close the terminal over there, will the flask server shut down (because when I close the terminal on my computer it shuts down the flask server and the results are no more available on localhost:5000)?.. It basically suggests me that I have to keep running the terminal all the time..please tell me what is the basic idea here? Thanks.
What you're asking is how you deploy your app. There are many options, that will depend on your needs, your hosting service, etc.
You should check the flask docs for the options. http://flask.pocoo.org/docs/deploying/
In essence, you'll have your flask app running as a local service on the server, so it's not shut down when you close the terminal, and an HTTP server that somehow proxies requests to that service. I guess the most popular is uWSGI with nginx.
When you upload your code to a remote host, you will need to provide a way to start the server and get things running. How this works is host- and software-dependent. As an example, here is some documentation for how you would fire Flask up on Heroku.
I am hosting a django-based site on a local machine (I have full access/control to it).
This site authenticates users against a remote active directory via the django ldap plugin.
authenticating against LDAP server used to work!
Now, when trying to authenticate against the LDAP server, the request just hangs until it times out. I couldn’t find anything useful in the logs.
The server setup is:
NginX, Django 1.3, Fedora 15, mySql 5.1.
I don’t know what logs I should try to look at.
(I've tried looking in nginx access and error logs but to no use.)
Things I tried:
Running the site on django's and accessing it via localhost (not going through Nginx, but accessing python manage.py directly, via the runserver command). this works
Running ldapsearch from the command line. this works
edit:
i used wireshark to look at the back-and-forth with the ldap server. the interaction seems to be fine - django sends a request to bind and it receives a success msg, and then sends a search query and a user object is returned. however, after this communication django seems to hang. when i "Ctrl-c" in the django shell after running "authenticate(username=user, password=pass)", the stack trace is sitting somewhere in the django-ldap library.
Please help, I have no idea what changed that caused this problem.
Thank you in advance
Active Directory does not allow anonymous binds for authorization; you can bind anonymously but you cannot do anything else.
Check if the user that is being used to bind with AD has valid credentials (ie, the account hasn't expired). If it has, you'll get these strange errors.