I'm working on creating my first "real" web app using Django.
Yesterday I learned I should be using a web server like Nginx to serve static files and pass off requests for dynamic content to my web app. I also learned that I need something like Gunicorn as the intermediary between the web server (Nginx) and my Django app.
My question is about virtualenv. It makes sense that we would contain app related software in it's own separate environment. What should I install in virtualenv, and what gets installed system wide? For example, in this guide we seem to install Python, Nginx and the database system wide (because they're installed before virtualenv is installed) while Django and Gunicorn are installed in virtualenv. It makes sense that Gunicorn would have to go in the virtualenv since its importing our python app, as explained here. Are the other things required to be installed system wide? Or can I pick either way? Is one way preferred over another?
Thanks!
Virtualenv is for managing Python libraries. It is not for managing Python itself, or for external services such as databases; it does however manage the Python libraries you use to access the database.
There's no room for confusion here, because there's simply no way to install Python itself or a database within a virtualenv.
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I am new to web development. I am not familiar with Django. I have written some Python scripts which do some intense calculations and graphs plotting using Python packages such as numpy, matlibplot and so on. I want to publish it as a web application on a server to be accessed by other computers.
So I am wondering, do I need to copy all the required packages into the project directory before deploying the application to a server? Or Django will automatically handle the Python packages dependencies upon deploying?
All the needed packages need to be installed on the server where is the web application running. If you have all the packages installed on your personal computer before deploy you will need to install the on the server as well.
You have to create virtual environment.
A virtual environment is a tool that helps to keep dependencies required by different projects separate by creating isolated python virtual environments for them.
I'm working on deploying a django app and I'm looking at a few tutorials which install apache within the virtualenv.
http://thecodeship.com/deployment/deploy-django-apache-virtualenv-and-mod_wsgi/
http://michal.karzynski.pl/blog/2013/09/14/django-in-virtualenv-on-webfactions-apache-with-mod-wsgi/
My question is that if I'm trying to deploy to a server that already has Apache installed on it, would installing a separate version of apache within the environment (as you would Django in general) overwrite any of the Apache settings currently on the server?
Using virtualenv doesn't mean installing a separate version of Apache. In fact, that's not even possible, because virtualenv is for Python libraries only.
Your Django app plus all its libraries lives in the virtualenv, but you use the system's Apache to serve it.
I have my development environment setup on Win 7 like this:
Django development structure
Apache -server- C:\Program Files (x86)\Apache Software Foundation\Apache2.4
PostgreSQL -database- C:\Program Files\PostgreSQL\9.2
Django -framework- C:\Python27\Lib\site-packages\django
Python -code- C:\Python27
Project -root- C:\mysite
|----------apps
|----------HTML
|----------CSS
|----------JavaScript
|----------assets
I am attempting to keep this extremely simple to start out. There are 5 main directories each with a distinct purpose. All the code resides in the project folder.
compared to WAMP structure:
C:\WAMP
|----------C:\Apache
|----------C:\MySQL
|----------C:\PHP
|----------C:\www
I like how Apache, MySQL, and PHP all reside in a neat directory. I know to keep the root project OUTSIDE in another directory in Django for security reasons.
Is it fine that Apache, PostgreSQL, and Python are installed all over the place in the Django environment?
Did I miss a core Django component and/or directory?
Will deploying and scaling be a problem?
I want this to be a guideline for beginning Django web programmers.
I can answer the question one by one:
Is if fine that Apache, PostgreSQL, and Python are installed all over the place in the Django environment?
All over the place sounds weird but yes it is totally fine.
Did I miss a core Django component and/or directory?
No you don't miss anything, Django core is in site-packages folder already and your site code is mysite, which can be located anywhere you want.
Will deploying and scaling be a problem?
No it won't be a problem with current structure. You will deploy your mysite only, the other will be installed separately.
Something you should get familiar with when starting with Django development:
Most likely when you deploy your project, it will be on a Linux server, so install and learn Linux maybe?
virtualenv: Soon you will have to install Django, then a bunch of external packages to support your project. virtualenv helps you isolate your working environment. Well it's "unofficial" a must when you start with python development.
virtualenvwrapper to make your life easier when working with virtualenv
git and github or bitbucket: if you don't know git yet, you should now.
Apache is just web server, it is used to serve files, but to make a website you do not necessary need it. Django comes with its own development server. See :
python manage.py runserver
Apache is required when you are developing PHP websites because your computer do not know how to compile and interpret it. But for Django, you use the Python language, and you have already install it if you are using Django.
Read https://docs.djangoproject.com/en/1.5/intro/tutorial01/
And where it will be the time to set up your own server using Apache look at :
https://docs.djangoproject.com/en/dev/howto/deployment/wsgi/modwsgi/.
Scaling will be a problem on windows. Python in Apache on windows gets 64 threads in one process. Couple this with the GIL and you will have scaling issues.
Python and Apache on Linux don't have this same problem. Under Linux wsgi can create multiple processes that have multiple threads each, minimizing GIL issues.
WSGI in Apache on windows is not a scalable solution in my opinion.
However you can develop there and move to linux for deployment, I do it all the time.
You will want to take advantage of the Apache Alias directive to serve all your static content like css, js, favicon.ico. This frees up python to only handle requests that require logic.
I am attempting to make a dynamic website for a school project. The problem is it has to be on the school server and I can't use any webframeworks. I have searched through google and stackoverflow but I can't seem to get an answer.
I have tried the code that was provided here:
How to implement a minimal server for AJAX in Python?
It worked on the local server but how can I change it so that it would open on the school server. When I used those codes, the page won't load or an internal error shows. Can someone point me in the right direction?
Using a web framework in python does not necessary needs a system package installation (like running a sudo apt-get install python-something).
In the end python frameworks are just files like in your project, but you can install them system wide (like in the apt-get example) or ship them within your project (probably what you want). Take a look at virtual environment for creating a self contained environment and setuptools foi packaging the application and its dependencies
For implementing an ajax server directly in python without a wsgi container (apache, nginx, etc) I recommend using flask. It is very, very simple and very powerful
I am trying to create my first site in Django and as I'm looking for example apps out there to draw inspiration from, I constantly stumble upon a term called "reusable apps".
I understand the concept of an app that is reusable easy enough, but the means of reusing an app in Django are quite lost for me. Few questions that are bugging me in the whole business are:
What is the preferred way to re-use an existing Django app? Where do I put it and how do I reference it?
From what I understand, the recommendation is to put it on your "PYTHONPATH", but that breaks as soon as I need to deploy my app to a remote location that I have limited access to (e.g. on a hosting service).
So, if I develop my site on my local computer and intend to deploy it on an ISP where I only have ftp access, how do I re-use 3rd party Django apps so that if I deploy my site, the site keeps working (e.g. the only thing I can count on is that the service provider has Python 2.5 and Django 1.x installed)?
How do I organize my Django project so that I could easily deploy it along with all of the reusable apps I want to use?
In general, the only thing required to use a reusable app is to make sure it's on sys.path, so that you can import it from Python code. In most cases (if the author follows best practice), the reusable app tarball or bundle will contain a top-level directory with docs, a README, a setup.py, and then a subdirectory containing the actual app (see django-voting for an example; the app itself is in the "voting" subdirectory). This subdirectory is what needs to be placed in your Python path. Possible methods for doing that include:
running pip install appname, if the app has been uploaded to PyPI (these days most are)
installing the app with setup.py install (this has the same result as pip install appname, but requires that you first download and unpack the code yourself; pip will do that for you)
manually symlinking the code directory to your Python site-packages directory
using software like virtualenv to create a "virtual Python environment" that has its own site-packages directory, and then running setup.py install or pip install appname with that virtualenv active, or placing or symlinking the app in the virtualenv's site-packages (highly recommended over all the "global installation" options, if you value your future sanity)
placing the application in some directory where you intend to place various apps, and then adding that directory to the PYTHONPATH environment variable
You'll know you've got it in the right place if you can fire up a Python interpreter and "import voting" (for example) without getting an ImportError.
On a server where you have FTP access only, your only option is really the last one, and they have to set it up for you. If they claim to support Django they must provide some place where you can upload packages and they will be available for importing in Python. Without knowing details of your webhost, it's impossible to say how they structure that for you.
An old question, but here's what I do:
If you're using a version control system (VCS), I suggest putting all of the reusable apps and libraries (including django) that your software needs in the VCS. If you don't want to put them directly under your project root, you can modify settings.py to add their location to sys.path.
After that deployment is as simple as cloning or checking out the VCS repository to wherever you want to use it.
This has two added benefits:
Version mismatches; your software always uses the version that you tested it with, and not the version that was available at the time of deployment.
If multiple people work on the project, nobody else has to deal with installing the dependencies.
When it's time to update a component's version, update it in your VCS and then propagate the update to your deployments via it.