I have a Flask Web Application that is periodically receiving JSON information from another application via HTTP POST.
My Flask Web Application is running on a CentOS 7 Server with Python 2.7.X.
I am able to parse the fields from this received JSON in the Flask Web Application and get some of the information that interests me. For example: I get some JSON input and extract an "ID":"7" field from it.
What I want to do now is run a perl script from within this Flask Web Application by using this "ID":"7".
Running 'perl my_perl_script.pl 7' manually on the command line works fine. What I want is for the Flask Web Application to perform this automatically whenever it receives an HTTP POST, by using the specific ID number found in this POST.
How can I do that in Flask?
Is it a good idea to do it with a subprocess call or should I consider implementing queues with Celery/rq? Or maybe some other solution?
I think the perl script should be invoked as a separate Linux process, independent of the Flask Web Application.
Thank you in advance :)
Sub,
I vote yes on subprocess, here's a post on SO about it. Control remains with Flask that way. An alternative might be to code a perl script that watchdogs for a trigger event depending on your needs, but that would put more of the process control on the perl side of things and less efficient use of resources.
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I'm building a web app using flask. I've made a completely separate python program and I want to run it in the backend of the web app. It is basically a program that takes in inputs and makes some calculations about scheduling and sends the user an email.
I don't know where or how to implement it into the web app.
normally one would implement such a manner with a message queue to pass it to a backend or with a database to persist these calculation jobs for another backend program.
If you want to stay with python flask is offering something for you called Celery
Jira Webhooks allows the user to specify the URL of an application that will receive data, in json format, when an event occurs. For example when an issue is updated in Jira. I want to create a python script that will receive this data and print it out. How is the best way to create this python script?
There are many ways to skin a cat, but basically you need a Web server, which can receive POST requests and knows how to read corresponding parameters.
Several possibilities:
Write simple script using builtin SimpleHTTPServer
Use some web framework (Django, Flask)
Deploy your python script to AWS Lambda and configure API Gateway
And here is an example application from Atlassian which can help you get started.
I'll briefly explain what I'm trying to achieve: We have a lot of servers behind ipvsadm VIPs (LVS load balancing) and we regularly move servers in/out of VIPs manually. To reduce risk (junior ops make mistakes...) I'd like to abstract it to a web interface.
I have a Python daemon which repeatedly runs "ipvsadm -l" to get a list of servers and statistics, then creates JSON from this output. What I'd now like to do is server this JSON, and have a web interface that can pass commands. For example, selecting a server in a web UI and pressing remove triggers an ipvsadm -d <server>... command. I'd also like the web UI to update every 10 seconds or so with the statistics from the list command.
My current Python daemon just outputs to a file. Should I somehow have this daemon also be a web server and serve its file and accept POST requests with command identifiers/arguments? Or a second daemon for the web UI? My only front end experience is with basic Bootstrap and jQuery usually backed by Laravel, so I'm not sure if there's a better way of doing this with sockets and some fancy JS modern-ism.
If there is a more appropriate place for this post, please move it if possible or let me know where to re-post.
You don't need fancy js application. To take the path of least resistance, I would create some extra application - if you like python, I recommend flask for this job. If you prefer php, then how about slim?
In your web application, if you want to make it fast and easy, you can even implement ajax mechanism fetching results based on interval to refresh servers' data every 10 seconds. You will fetch it from json served by independent, already existing deamon.
Running commands clicked on Web UI can be done by your web application.
Your web application is something extra and I find it nice to be separated from deamon which fetch data about servers and save it as json. Anytime you can turn off the page, but all statistics will be still fetching and available for console users in json format.
I'm looking for a bit of web development advice. I'm fairly new to the area but I'm sure there are some gurus out there willing to part with some wisdom.
Objective: I'm interested in controlling a Python application on my computer from my personal web hosted site. I know, this question has been asked several times before but in each case the requirements were a bit different from my own. To reduce the length of this post I'll summarize my objective in a few bullet points:
Personal site is hosted by a web hosting company
Site uses HTML, PHP, MySQL, Python and JavaScript, the majority of everything is coded by me from the ground up
An application that is coded in Python will run on a PC within my home and will communicate with an Arduino board
The app will receive commands from the internet to control actuation via the Arduino, and will transmit sensor data back to the site (such as temperature)
Looking for the communication to be bi-directional, fast and secure
Securing the connection between site and Python app would be most ideal
I'm not looking to connect to the Python application directly, the web server must serve as the 'middle man'
So far I've considered HTTP Post and HTML forms, using sockets (Python app would run as a web server), an IRC bot and reading/writing to a text file stored on the web server.
I was also hoping to have a way to communicate with the Python app without needing to refresh the webpage, perhaps using AJAX or JavaScipt? Maybe with Flash?
Is there something I'm not considering? I feel like I'm missing something. Thanks in advance for the advice!
Just thinking out loud for how I would start out with this. First, regarding the website itself, you can just use what's easiest to you, or to the environment you're in. For example, a basic PHP page will do just fine, but if you can get a site running in Python as well, I'd prefer using the same language all over.
That said, I'm not sure why you would need to use a hosted website? Given that you're already forced to have a externally accessible PC at home for the communication, why not run a webserver on that directly (Apache, Nginx, or even something like CherryPy should do)? That webserver can then communicate with the python process that is running to control your Arduino (by using e.g. Python's xmlrpclib). If you would run things via the hosting company, you would still need some process that can handle external requests securely... something a webserver is quite good at. Just running it yourself gives you all the freedom you want, and simplifies things by lessening the number of components in your solution.
The updates on your site I'd keep quite basic: commands you want to run can be handled in the request handlers of the webserver by just calling the relevant (xmlrpclib) calls. Dynamically updating the page is best done by some AJAX calls I reckon. Based on your story, these updates are easily put in a JSON object, suitable for periodically updating only the relevant segments of your page.
I am currently working on a project to create simple file uploader site that will update the user of the progress of an upload.
I've been attempting this in pure python (with CGI) on the server side but to get the progress of the file I obviously need send requests to the server continually. I was looking to use AJAX to do this but I was wondering how hard it would be to, instead of changing to some other framerwork (web.py for instance), just write my own web server for receiving the XML HTTP Requests?
My main problem is that sending the request is done from HTML and Javascript so it all seems like magic trickery at the moment.
Can anyone advise me as to the best way to go about receiving these requests on the server?
EDIT: It seems that a framework would be the way to go. Would web.py be a good route to take?
I would recommend to use a microframework like Sinatra for Ruby. There seem to be some equivalents for Python. What python equivalent of Sinatra would you recommend?
Such a framework allows you to simply map a single method to a route.
Writing a very basic HTTP server won't be very hard (see http://docs.python.org/library/simplehttpserver.html for an example), but you will be missing many features that are provided by real servers and web frameworks.
For your project, I suggest you pick one of the many Python web frameworks and run your application behind Apache/mod_wsgi.
There's absolutely no need to write your own web server. Plenty of options exist, including lightweight ones like nginx.
You should use one of those, and either your own custom WSGI code to receive the request, or (better) one of the microframeworks like Flask or Bottle.