I would like to deploy several WSGI web applications with Twisted on a debian server, and need some direction for a solid production setup. These applications will be running 24/7.
I need to run several configurations, each binding to different ports/interfaces/privileges.
I want to do as much of this in python as possible.
I do not want to package my applications with a program like 'tap2deb'.
What is the best way to implement each application as a system service? Do I need some /etc/init.d shell scripts, or can I manage this with python? (I don't want anything quite as heavy as Daemontools)
If I use twistd to manage most of the configuration/process management, what kind of wrappers/supervisors do I need to put in place?
I would like centralized management, but restricting control to the parent user account is not a problem.
The main problem I want to avoid, is having to SSH into my server once a day to restart a blocking/crashed application
I have found several good references for launching daemon processes with python. See daemoncmd from pypi.
Im still coming up a little short on the monitoring/alert solutions (in python).
I need to develop a daemon service which also has presence in System Tray. The system tray icon allows users to customize/access some options through right click menu. It might open a window as well manage those options in a better way.
The app would mostly be communicating with a RESTful service, posting and downloading files.
Now I know that for any daemon service, it needs to be native. However we don't have the luxury to maintain 3 different dev pipelines, specially since the app is experimental(but might land up in hands of users)
I have experience in Java/Scala, followed by C++/Python/JS. I would prefer java/Scala (existing codebase) but open to frameworks in other languages.
I was thinking of doing a scala based app with swing for windowing, but it is not pretty.
Any ideas?
We have an App, same base code, running on Windows, OSX and Linux (with system tray) using these two set of components:
The Tanuki Java Service Wrapper to handle the lifecycle of the app. It also allows installing the component as a "native" windows service. Version 3.2.3 is under LGPL if that helps.
The Java 6 java.awt.SystemTray which is supported on most platforms. On OSX, we use a modified version of macify to implement OSX specific gimmicks like doc icons
You could go with JavaFX and the ScalaFX bindings. They look to be very actively maintained, and the syntax seems pretty clean. Only trouble is that it seems to have poor support for using the system tray - see this discussion for details and some workarounds.
You can use Real Studio to create a Windows Service and OS X/Linux daemons. Real Studio creates native apps for Windows, OS X and Linux.
I have a Linux web application which installs a webserver, a database, digital certificates etc using a set of .sh scripts.
In order to simplify user interaction during installation such as entering passwords, certificate details and such, I want to create a GUI installer. After much deliberation, following are some decisions and related questions
The target systems may or may not have a Desktop or a monitor installed. So providing a web interface to the install process may be the way to go. User would copy the application to the target machine, start the webservice which would then expose a web interface to continue the install. Would Python be a good choice for this?
Since this is an installer itself, the requirements to run it must be practically nil. This requires
Use python's built in SimpleHTTPServer. This will be used the one time during installation and then be killed. Any caveats to using the default python web server?
Compile app into standalone binary using one of the Freezing utilities. We don't want to depend on the user having python on their system and have been asked to account for admins who've removed python due to whatever reason. Is this precaution necessary?
Any comments on the general approach or alternative options will be greatly appreciated.
I have a Django application that I would like to deploy to the desktop. I have read a little on this and see that one way is to use freeze. I have used this with varying success in the past for Python applications, but am not convinced it is the best approach for a Django application.
My questions are: what are some successful methods you have used for deploying Django applications? Is there a de facto standard method? Have you hit any dead ends? I need a cross platform solution.
I did this a couple years ago for a Django app running as a local daemon. It was launched by Twisted and wrapped by py2app for Mac and py2exe for Windows. There was both a browser as well as an Air front-end hitting it. It worked pretty well for the most part but I didn't get to deploy it out in the wild because the larger project got postponed. It's been a while and I'm a bit rusty on the details, but here are a few tips:
IIRC, the most problematic thing was Python loading C extensions. I had an Intel assembler module written with C "asm" commands that I needed to load to get low-level system data. That took a while to get working across both platforms. If you can, try to avoid C extensions.
You'll definitely need an installer. Most likely the app will end up running in the background, so you'll need to mark it as a Windows service, Unix daemon, or Mac launchd application.
In your installer you'll want to provide a way to locate a free local TCP port. You may have to write a little stub routine that the installer runs or use the installer's built-in scripting facility to find a port that hasn't been taken and save it to a config file. You then load the config file inside your settings.py and whatever front-end you're going to deploy. That's the shared port. Or you could just pick a random number and hope no other service on the desktop steps on your toes :-)
If your front-end and back-end are separate apps then you'll need to design an API for them to talk to each other. Make sure you provide a flag to return the data in both raw and human-readable form. It really helps in debugging.
If you want Django to be able to send notifications to the user, you'll want to integrate with something like Growl or get Python for Windows extensions so you can bring up toaster pop-up notifications.
You'll probably want to stick with SQLite for database in which case you'll want to make sure you use semaphores to tackle multiple requests vying for the database (or any other shared resource). If your app is accessed via a browser users can have multiple windows open and hit the app at the same time. If using a custom front-end (native, Air, etc...) then you can control how many instances are running at a given time so it won't be as much of an issue.
You'll also want some sort of access to local system logging facilities since the app will be running in the background and make sure you trap all your exceptions and route it into the syslog. A big hassle was debugging Windows service startup issues. It would have been impossible without system logging.
Be careful about hardcoded paths if you want to stay cross-platform. You may have to rely on the installer to write a config file entry with the actual installation path which you'll have to load up at startup.
Test actual deployment especially across a variety of firewalls. Some of the desktop firewalls get pretty aggressive about blocking access to network services that accept incoming requests.
That's all I can think of. Hope it helps.
If you want a good solution, you should give up on making it cross platform. Your code should all be portable, but your deployment - almost by definition - needs to be platform-specific.
I would recommend using py2exe on Windows, py2app on MacOS X, and building deb packages for Ubuntu with a .desktop file in the right place in the package for an entry to show up in the user's menu. Unfortunately for the last option there's no convenient 'py2deb' or 'py2xdg', but it's pretty easy to make the relevant text file by hand.
And of course, I'd recommend bundling in Twisted as your web server for making the application easily self-contained :).
I'm running Mac OS X Leopard and wanted to know what the easy way to setup a web development environment to use Python, MySQL, Apache on my machine which would allow me to develop on my Mac and then easily move it to a host in the future.
I've been trying to get mod_wsgi installed and configured to work with Django and have a headache now. Are there any web hosts that currently use mod_wsgi besides Google, so I could just develop there?
FWIW, we've found virtualenv [http://pypi.python.org/pypi/virtualenv] to be an invaluable part of our dev setup. We typically work on multiple projects that use different versions of Python libraries etc. It's very difficult to do this on one machine without some way to provide a localized, customized Python environment, as virtualenv does.
Most Python applications are moving away from mod_python. It can vary by framework or provider, but most development effort is going into mod_wsgi.
Using the WSGI standard will make your Python application server agnostic, and allow for other nice additions like WSGI middleware. Other providers may only provide CGI (which won't scale well performance wise), or FastCGI.
I've worked with Django using only the included server in the manager.py script and have not had any trouble moving to a production environment.
If you put your application in a host that does the environment configuration for you (like WebFaction) you should not have problems moving from development to production.
I run a Linux virtual machine on my Mac laptop. This allows me to keep my development environment and production environments perfectly in sync (and make snapshots for easy experimentation / rollback). I've found VMWare Fusion works the best, but there are free open source alternatives such as VirtualBox if you just want to get your feet wet.
I share the source folders from the guest Linux operating system on my Mac and edit them with the Mac source editor of my choosing (I use Eclipse / PyDev because the otherwise excellent TextMate doesn't deal well with Chinese text yet). I've documented the software setup for the guest Linux operating system here; it's optimized for serving multiple Django applications (including geodjango).
For extra added fun, you can edit your Mac's /etc/hosts file to make yourdomainname.com resolve to your guest Linux boxes internal IP address and have a simple way to work on / test multiple web projects online or offline without too much hassle.
What you're looking for is Mod_Python. It's an Apache-based interpreter for Python. Check it out here:
http://www.modpython.org/
Google App Engine has done it for you. Some limitations but it works great, and it gives you a path to hosting free.
Of course Mac OS X, in recent versions, comes with Python and Apache. However you may want to have more flexibility in the versions you use, or you may not like the tweaks Apple has made to the way they are configured. A good way to get a more generic set of tools, including MySQL, is to install them anew. This will help your portability issues. The frameworks can be installed relatively easily with one of these open source package providers.
Fink
MacPorts
MAMP
mod_wsgi is really, really simple.
Pyerweb is a really simple (~90 lines including comments/whitespace) WSGI-compliant routing-framework I wrote. Basically the WSGI API is just a function that gets passed environ, and wsgi_start_response, and it returns a string.
envrion is a dict with the request info, for example environ['PATH_INFO'] is the request URI)
wsgi_start_response which is a callable function which you execute to set the headers,:
wsgi_start_response(output_response, output_headers)
output_response is the string containing the HTTP status you wish to send (200 OK etc), and output_headers is a list-of-tuples containing your headers (for example, [("Content-type", "text/html")] would set the content-type)
Then the function returns a string containing your output.. That's all there is to it!
To run it, using spawning you can just do spawn scriptname.my_wsgi_function_nae and it will start listening on port 8080.
To use it via mod_wsgi, it's documentation is good, http://code.google.com/p/modwsgi/wiki/QuickConfigurationGuide and there is a django specific section
The up-side to using mod_wsgi is it's the standard for serving Python web-applications. I recently decided to play with Google App Engine, and was surprised when Pyerweb (which I linked to at the start of this answer) worked perfectly on it, completely unintentionally. I was even more impressed when I noticed Django applications run on it too.. Standardisation is a good thing!
You may want to look into web2py. It includes an administration interface to develop via your browser. All you need in one package, including Python.
Check out WebFaction—although I don't use them (nor am I related to / profit from their business in any way). I've read over and over how great their service is and particularly how Django-friendly they are. There's a specific post in their forums about getting up and running with Django and mod_wsgi.
Like others before me in this thread, I highly recommend using Ian Bicking's virtualenv to isolate your development environment; there's a dedicated page in the mod_wsgi documentation for exactly that sort of setup.
I'd also urge you to check out pip, which is basically a smarter easy_install which knows about virtualenv. Pip does two really nice things for virtualenv-style development:
Knows how to install from source control (SVN, Git, etc...)
Knows how to "freeze" an existing development environement's requirements so that you can create that environment somewhere else—very very nice for multiple developers or deployment.