Is there a conventional way to run python scripts from a Ruby on Rails webserver?
I have a Ruby on Rails site that is currently deployed to Heroku (I can deploy to AWS or wherever this is possible).
I would like for people to upload, and execute arbitrary python scripts on certain page requests (that we review for security). The python scripts should be relatively short running (few seconds tops), mostly to parse or process data. Ideally we would let users upload a script in any language, but python is the most important for now.
There are several ways to do this. The most obvious one would be to write another web service, this one in Python, but that's hardly elegant. Another solution:
Install rubypython gem.
Then you can do things like:
require 'rubypython'
RubyPython.start
my_python_module = RubyPython.import('my.python.module')
value = my_python_module.my_python_function().rubify
RubyPython.stop
You can see more at rubypython documentation pages.
A third option would be to simply shell out and execute Python as any executable, through IO.popen.
Related
I have a python server that I need to run in both a Linux and Windows environment, and my question is about deployment. What is the best method for deploying the solution instead of just double clicking on the file and running it?
Since I use the server_forever() on the server, I can just run the script from command line, but this keeps the python window open. If I log off the machine, naturally the process will stop. So what is the best method for deploying a python script that needs to keep running if the user is logged in or off a machine.
Since I am going to be using multiple environment, Linux and Windows, can you please be specific in what OS you are talking about?
For windows, I was thinking of running the script 'At Startup' using the Windows scheduler. But I wanted to see if anyone had a better option. For linux, I really don't know what to create. I am assuming a CRON job?
Deployment does refer to coding, so using serve_forever() on a multiprocessing job manager keeps the python window open upon execution. Is there a way to hide this window through code? Would you recommend using a conversion tool like py2exe instead?
This is the subject matter of a whole library of books, so I will just give an introduction here :-)
You can basically start scripts directly and then have multiple options to do this in a way that they keep running in the background.
If you have certain functionality that needs to run on regular moments, you would do this by scheduling it:
Windows: Windows Scheduler or specific scheduling tools
Linux: Cron
If your problem is that you want to start a script without it closing on you while SSH'ing into Linux, you want to look into the "screen" or "tmux" tools.
If you want to have it started automatically this could be done by using the "At Startup" as you point out and Linux has similar functionalities, but the preferred and more robust way would be to set up a service that is better integrated with the OS.
Windows: Windows Service
Linux: Daemon
Even more capabilities can be yielded by using an application server such a Django
Tomcat (see comment) is an option, but definitely not the standard one; you'll have a hard time finding support both from Tomcat people running Python or Python people running their stuff on Tomcat. That being said, I imagine you could enable CGI and have it run a Python command with your script.
Yet, instead of just starting a Python script I would strongly encourage you to have a look at different Python options that are probably available for your specific use case. From lightweight web solutions like Flask over a versatile networking engine like Twisted to a full blown web framework like Django.
They all have rather well-thought-out deployment solutions available. Look up WSGI for more background.
For very simple, internal web-apps using ASP I was able to just switch IIS 'on' and then write some ASP scripts in the www directory that would start working immediately.
Is there an equivalent webserver app for Python scripts that I can run that will automatically start serving dynamic pages (python scripts) in a certain folder (with virtually no configuration)?
Solutions I've already found are either too limited (e.g. SimpleHTTPRequestHandler doesn't serve dynamic content) or require configuring the script that does the serving.
There's always CGI. Add a script mapping of .py to "C:\Python27\python.exe" -u "%s" then drop .py files in a folder and IIS will execute them.
I'd not generally recommend it for real work—in the longer term you would definitely want to write apps to WSGI, and then deploy them through any number of interfaces including CGI—but it can be handy for quick prototyping.
For development or just to play around, here's an example using the standard Python library that I have used to help friend who wanted to get a basic CGI server up and running. It will serve python scripts from cgi-bin and files from the root folder. I'm not near a Windows computer at the moment to make sure that this still works. This also assumes Python2.x. Python 3.x has this, it's just not named the same.
Make a directory on your harddrive with a cgi-bin folder in it (Ex. "C:\server\cgi-bin")
In a command window, navigate to "C:\server" directory
Type the following assuming you've installed python 2.7 in C:\Python27:
"c:\python27\python.exe -m CGIHTTPServer"
You should get a message like "Serving HTTP on 0.0.0.0 port 8000"
Linux is the same - "python -m CGIHTTPServer" in a directory with a cgi-bin/ in it.
WSGI setups are fairly easy to get started, but in no anyway turn key. django MVC has a simple built in development server if you plan on using a more comprehensive framework.
My limited experience with Python web frameworks has taught me that most go to one extreme or the other: Django on one end is a full-stack MVC framework, that will do pretty much everything for you. On the other end, there are Flask, web.py, CherryPy, etc., which do much less, but stay out of your way.
CherryPy, for example, not only comes with no ORM, and doesn't require MVC, but it doesn't even have a templating engine. So unless you use it with something like Cheetah, you can't write what would look like .asp at all.
I have a Rails server which will need to run a python script at the background. I know that I can run it like I run terminal commands in ruby, but how is the performance like? is it better to use a python framework and not Rails? Is there better ways (optimization wise) to run python scripts on a Rails server?
If you mean that it needs to run periodically, just set it up as a cron job, no special performance characteristics to worry about there.
If you mean that it needs to run when pages are requested from your Ruby website, then simply running the script each time won't perform well as it needs to fire up the Python interpreter over and over again.
If the Python script is large but is only called from a relatively small number of page requests, you might be able to get away with this, sometimes it's not worth the time to optimise a slow operation that isn't called often.
If the bulk of your website is based around the functionality of the Python script, then yes, you are probably better off switching to a Python web framework and loading it as a module.
If the Python script isn't very big, then you are probably better off rewriting it in Ruby.
Worst case scenario is that the script is big and used often, but doesn't make up enough of your website to justify switching to Python. In that case, I'd consider wrapping the Python in a daemon that Ruby can talk to in the background.
You will incur the cost of starting python each time you run it from ruby. The cost would be the same in a python framework, unless you could use the python script as a library instead.
You could setup a daemon in rails to execute the python script.
http://railscasts.com/episodes/129-custom-daemon - Tutorial for setting up daemons in rails
How can we call the CLI executables commands using Python
For example i have 3 linux servers which are at the remote location and i want to execute some commands on those servers like finding the version of the operating system or executing any other commands. So how can we do this in Python. I know this is done through some sort of web service (SOAP or REST) or API but i am not sure....... So could you all please guide me.
Depends on how you want to design your software.
You could do stand-alone scripts as servers listening for requests on specific ports,
or you could use a webserver which runs python scripts so you just have to access a URL.
REST is one option to implement the latter.
You should then look for frameworks for REST development with python, or if it’s simple logic with not so many possible requests can do it on your own as a web-script.
Maybe you should take a look at Pushy, which allows to connect to remote machines through SSH and make them execute various Python functions. I like using it because there are no server-side dependencies except the SSH server and a Python interpreter, and is therefore really easy to deploy.
Edit: But if you wish to code this by yourself, i think SOAP is a nice solution, the SOAPpy module is great and very easy to use.
You can use Twisted,
It is easy create ssh clients or servers.
Examples:
http://twistedmatrix.com/documents/current/conch/examples/
I am rookie in python - have experience in PHP
my service provider (Bluehost) say that python 2.6 is available, however I am not able to run any script (basic hello word) on it - probably because I try do it PHP way. create a script.php file and place the link to it in browser... :)
Where I can find explanation for dummy like me what I should do with file script.py (hello world inside) in order to be executed and displayed in browser, I am guessing that compilation could be required
thank you
Bensiu
If you're using Apache, this simple tutorial will show you how to configure it and run a python "hello world" script (in the simplest, old-fashioned way: as a CGI script).
This system-administration/configuration part will of course be different with other web servers, or other and better way of running Python web app (WSGI in particular), but then, you're not telling us what server or approach (CGI vs WSGI vs others yet) you want to use, so, this is probably the best we can suggest!-)