In order to redeploy a GAE application, I currently have to install the GAE deployment tools on the system that I am using for deployment. While this process is relatively straight forward, the deployment process is a manual process that does not work from behind a firewall and the deployment tools must be installed on every machine that will be used for updating GAE apps. A more ideal solution would be if I could update a GAE application from another GAE application that I have deployed previously. This would remove the need to have multiple systems configured to deploy apps.
Since the GAE deployment tools are written in Python and the GAE App Engine supports Python, is it possible to modify appcfg.py to work from within GAE? The use case would be to pull a project from GitHub or some other online repository and update one GAE application from another GAE app. If this is not possible, what is the limiting constraint?
Is it possible? Yes. The protocol appcfg uses to update apps is entirely HTTP-based, so there's absolutely no reason you couldn't write an app that's capable of deploying other apps (or redeploying itself - self-modifying code)! You may even be able to reuse large parts of appcfg.py to do it.
Is it easy? Probably not. It's quite likely you'll need to understand a decent chunk of appcfg's internals, and the RPCs it uses to upload new apps - not a trivial undertaking. You'll also need to store your credentials in the app, in all likelihood - though you can use a role account that is and admin only for the apps it's deploying to minimize risk there.
One limiting constraint could be the protocol that the python sdk uses to communicate with the GAE servers. If it only uses HTTP, you might be OK. but if it's anything else, you might be out of luck because you can't open a socket directly from within GAE.
What problem did you have by trying to update behind a firewall?
I've got some, but finally I manage to work around them.
About your question, the constraint is that you cannot write files into a GAE app, so even though you could possibly pull from the VCS you can't write those pulled files.
So you would have to update from outside the GAE in first place.
Anyway every machine that needs to update the GAE should have the SDK anyway just to see if they changes work.
So, If you really want to do this you have two alternatives:
Host your own "updater" site and istall the SDK there, then when you want to update log into your side ( or run a script ) and do the remote update.
Although I don't know Amazon EC2 well, I think you can do pretty much the same thing as op 1 from there.
Finally I think the password to update has to be typed always. ( you could have the SDK of the App engine and modify that, because it is open source )
Related
I'm relatively new to web development, but I have a couple years experience working with python, so I figured I would build my first production site using django.
I've spent the last few days learning the basics and building a test site running on my local machine. Today, I've been trying to deploy my site to production; however, I've hit a pretty large stumbling block.
The django documentation suggests using mod_wsgi for apache deployments. I followed the install instructions here, only to realize that I don't have access to make any changes to apache - I'm currently on a shared hosting plan.
Apparently, to perform the install, I would have to upgrade to a VPS plan, which costs a lot more.
Any advice for a new web developer trying to get a proof-of-concept web app together (preferably with feedback gathered from real users) on a budget?
I think I have two options:
Eat the cost on my current web hosting plan. Try to find a cheaper host that specializes in django hosting. I've been looking at the following (suggestions here would be wonderful):
Heroku
DigitalOcean
A2Hosting
Try some sort of manual deployment. Is this possible or has anybody ever made this work? I can't seem to find any resources about this.
I was able to install django on my web server and my site just seems like a collection of files at this point. Can I simply move this directory tree to my site using an ftp? And handle the database migration manually?
Can I just run django on my web server via ssh instead of from my local machine? Essentially just rebuild my site in production? I know this isn't a smart idea with a normal production site, but as a proof of concept, I don't mind some downtime if my code is buggy.
Thanks!
If you are just starting Heroku is probably perfect for you. It's super easy to set up, you don't have to handle the server configuration yourself and it has a free tier to do some tests until you are ready to go.
If you are OK with doing some more advanced server/service configuration, you can use Google Cloud, Azure or AWS. This last one has a one year free tier. If you go this route, I suggest using gunicorn/uwsgi + nginx instead of Apache mod_wsgi.
I have been looking at setting up a web server to use Python and I have installed Apache 2.2.22 on Debian 7 Wheezy with mod_wsgi. I have gotten the initial page up and going and the Apache will display the contents of the wsgi file that I have in my directory.
However, I have been researching on how to deploy a Python application and I have to admin, I find some of it a little confusing. I am coming from a background in PHP where it is literally install what you need and you are up and running and PHP is processing the way it should be.
Is this the same with Python? I can't seem to get anything to process outside of the wsgi file that I have setup. I can't import anything from other files without the server throwing a "500" error. I have looked on Google and Bing to try to find an answer to this, but I can't seem to find anything, or don't know that what I have been looking at is the answer.
I really appreciate any help that you guys can offer.
Thanks in advance! (If I need to post any coding, I can do that, I just don't know what you guys would need, if anything, as far as coding examples for this...)
Python is different from PHP in that PHP executes your entire program separately for each hit to your website, whereas Python runs "worker processes" that stay resident in memory.
You need some sort of web framework to do this work for you (you could write your own, but using someone else's framework makes it much easier). Flask is an example of a light one; Django is an example of a very heavy one. Pick one and follow that framework's instructions, or look for tutorials for that framework. Since the frameworks differ, most practical documentation on handling web services with Python are focused around a framework instead of just around the language itself.
Nearly any python web framework will have a development server that you can run locally, so you don't need to worry about deploying yet. When you are ready to deploy, Apache will work, although it's usually easier and better to use Gunicorn or another python-specific webserver, and then if you need more webserver functionality, set up nginx or Apache as a reverse proxy. Apache is a very heavy application to use for nothing but wsgi functionality. You also have the option of deploying to a PaaS service like Heroku (free for development work, costs money for production applications) which will handle a lot of sysadmin work for you.
As an aside, if you're not using virtualenv to set up your Python environment, you should look into it. It will make it much easier to keep track of what you have installed, to install new packages, and to isolate an environment so you can work on multiple projects on the same computer.
Is there any lightweight mvc webframework which is not necessary to install to the server?
I need something simple, that i could just copy to the shared hosting. And it must handle urls other that localhost/test.py, something like this localhost/Blog/test
You should probably check out Flask or Bottle, two nice Python microframeworks. With an appropriate "main" Python script (to initialize your app and dispatch requests to it) and mod_rewrite rules in place, you can probably get pretty close to your goal of "just copy[ing] to the shared hosting" with nice URLs.
Flask has good documentation on deploying via CGI, which is what you might have to use on your shared host. (If your host supports FastCGI or mod_wsgi, those deployment options would be preferable.)
Checkout web2py. Seems to be about the simplest python based webserver I can think of.
Django might do, it's hefty, but it comes with it's own development server.
web2py includes everything (ssl-enabled web server, sqlite sql based transaction safe database, web based Integrated Development Enviroment, web based database interface) in one package. The web2py binaries for windows and mac also include Python itself. web2py does not require configuration or installation and can run off a usb drive. It was originally developed as a teaching tool for MVC.
checkout https://github.com/salimane/bottle-mvc or https://github.com/salimane/flask-mvc . They are boilerplates that could get you started with controllers, models in separate folders. They are based on bottle and flask micro frameworks, no useless features, they give you the flexibility to plugin whatever modules you want.
Is it possible to run django without shell access? My hoster supports the following for 5€/month:
python (I assume via mod_python)
mysql
There is no shell nor cronjob support, which costs additional 10€/month, so I'm trying to avoid it.
I know that Google Apps also work without shell access, but I assume that is possible because of their special configuration.
It's possible but not desirable. Having shell access makes it possible to centralise things properly using symlinks.
Get a better host would be my first suggestion. WebFaction is the most recommended shared host for using with Django.
If that's out of your price range, there are plenty of hosts that give you a proper system account (vs just a ftp account) and have mod_python or mod_wsgi (preferred now).
Google Apps works without shell because their system looks for a dispatcher script that you have to write to an exact specification.
It is possible.
Usually you will develop your application locally (where shell access is nice to have) and publish your work to your server. All you need for this is FTP access and some way to import a database dump from your development database (often hosters provide an installation of phpMyAdmin for this).
python (I assume via mod_python)
From my experience, you are most certainly wrong with that assumption. Many low-cost providers claim to support python but in fact provide only an outdated version that can be used with CGI scripts. This setup will have a pretty low performance for Django apps.
Good morning.
As the title indicates, I've got some questions about using python for web development.
What is the best setup for a development environment, more specifically, what webserver to use, how to bind python with it. Preferably, I'd like it to be implementable in both, *nix and win environment.
My major concern when I last tried apache + mod_python + CherryPy was having to reload webserver to see the changes. Is it considered normal? For some reason cherrypy's autoreload didn't work at all.
What is the best setup to deploy a working Python app to production and why? I'm now using lighttpd for my PHP web apps, but how would it do for python compared to nginx for example?
Is it worth diving straight with a framework or to roll something simple of my own? I see that Django has got quite a lot of fans, but I'm thinking it would be overkill for my needs, so I've started looking into CherryPy.
How exactly are Python apps served if I have to reload httpd to see the changes? Something like a permanent process spawning child processes, with all the major file includes happening on server start and then just lazy loading needed resources?
Python supports multithreading, do I need to look into using that for a benefit when developing web apps? What would be that benefit and in what situations?
Big thanks!
What is the best setup for a development environment?
Doesn't much matter. We use Django, which runs in Windows and Unix nicely. For production, we use Apache in Red Hat.
Is having to reload webserver to see the changes considered normal?
Yes. Not clear why you'd want anything different. Web application software shouldn't be dynamic. Content yes. Software no.
In Django, we develop without using a web server of any kind on our desktop. The Django "runserver" command reloads the application under most circumstances. For development, this works great. The times when it won't reload are when we've damaged things so badly that the app doesn't properly.
What is the best setup to deploy a working Python app to production and why?
"Best" is undefined in this context. Therefore, please provide some qualification for "nest" (e.g., "fastest", "cheapest", "bluest")
Is it worth diving straight with a framework or to roll something simple of my own?
Don't waste time rolling your own. We use Django because of the built-in admin page that we don't have to write or maintain. Saves mountains of work.
How exactly are Python apps served if I have to reload httpd to see the changes?
Two methods:
Daemon - mod_wsgi or mod_fastcgi have a Python daemon process to which they connect. Change your software. Restart the daemon.
Embedded - mod_wsgi or mod_python have an embedded mode in which the Python interpreter is inside the mod, inside Apache. You have to restart httpd to restart that embedded interpreter.
Do I need to look into using multi-threaded?
Yes and no. Yes you do need to be aware of this. No, you don't need to do very much. Apache and mod_wsgi and Django should handle this for you.
So here are my thoughts about it:
I am using Python Paste for developing my app and eventually also running it (or any other python web server). I am usually not using mod_python or mod_wsgi as it makes development setup more complex.
I am using zc.buildout for managing my development environment and all dependencies together with virtualenv. This gives me an isolated sandbox which does not interfere with any Python modules installed system wide.
For deployment I am also using buildout/virtualenv, eventually with a different buildout.cfg. I am also using Paste Deploy and it's configuration mechanism where I have different config files for development and deployment.
As I am usually running paste/cherrypy etc. standalone I am using Apache, NGINX or maybe just a Varnish alone in front of it. It depends on what configuration options you need. E.g. if no virtual hosting, rewrite rules etc. are needed, then I don't need a full featured web server in front. When using a web server I usually use ProxyPass or some more complex rewriting using mod_rewrite.
The Python web framework I use at the moment is repoze.bfg right now btw.
As for your questions about reloading I know about these problems when running it with e.g. mod_python but when using a standalone "paster serve ... -reload" etc. it so far works really well. repoze.bfg additionally has some setting for automatically reloading templates when they change. If the framework you use has that should be documented.
As for multithreading that's usually used then inside the python web server. As CherryPy supports this I guess you don't have to worry about that, it should be used automatically. You should just eventually make some benchmarks to find out under what number of threads your application performs the best.
Hope that helps.
+1 to MrTopf's answer, but I'll add some additional opinions.
Webserver
Apache is the webserver that will give you the most configurability. Avoid mod_python because it is basically unsupported. On the other hand, mod_wsgi is very well supported and gives you better stability (in other words, easier to configure for cpu/memory usage to be stable as opposed to spikey and unpredictable).
Another huge benefit, you can configure mod_wsgi to reload your application if the wsgi application script is touched, no need to restart Apache. For development/testing servers you can even configure mod_wsgi to reload when any file in your application is changed. This is so helpful I even run Apache+mod_wsgi on my laptop during development.
Nginx and lighttpd are commonly used for webservers, either by serving Python apps directly through a fastCGI interface (don't bother with any WSGI interfaces on these servers yet) or by using them as a front end in front of Apache. Calls into the app get passed through (by proxy) to Apache+mod_wsgi and then nginx/lighttpd serve the static content directly.
Nginx has the added advantage of being able to serve content directly from memcached if you want to get that sophisticated. I've heard disparaging comments about lighttpd and it does seem to have some development problems, but there are certainly some big companies using it successfully.
Python stack
At the lowest level you can program to WSGI directly for the best performance. There are lots of helpful WSGI modules out there to help you in areas you don't want to develop yourself. At this level you'll probably want to pick third-party WSGI components to do things like URL resolving and HTTP request/response handling. A great request/response component is WebOb.
If you look at Pylons you can see their idea of "best-of-breed" WSGI components and a framework that makes it easier than Django to choose your own components like templating engine.
Django might be overkill but I don't think that's a really good argument against. Django makes the easy stuff easier. When you start to get into very complicated applications is where you really need to look at moving to lower level frameworks.
Look at Google App Engine. From their website:
Google App Engine lets you run your
web applications on Google's
infrastructure. App Engine
applications are easy to build, easy
to maintain, and easy to scale as your
traffic and data storage needs grow.
With App Engine, there are no servers
to maintain: You just upload your
application, and it's ready to serve
your users.
You can serve your app using a free
domain name on the appspot.com domain,
or use Google Apps to serve it from
your own domain. You can share your
application with the world, or limit
access to members of your
organization.
App Engine costs nothing to get
started. Sign up for a free account,
and you can develop and publish your
application for the world to see, at
no charge and with no obligation. A
free account can use up to 500MB of
persistent storage and enough CPU and
bandwidth for about 5 million page
views a month.
Best part of all: It includes Python support, including Django. Go to http://code.google.com/appengine/docs/whatisgoogleappengine.html
When you use mod_python on a threaded Apache server (the default on Windows), CherryPy runs in the same process as Apache. In that case, you almost certainly don't want CP to restart the process.
Solution: use mod_rewrite or mod_proxy so that CherryPy runs in its own process. Then you can autoreload to your heart's content. :)