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An egg is Python’s new distribution format, comparable to a .jar in Java.
It’s basically a zip file with a particular directory structure containing the
code and a bit of metadata. You can get details on eggs directly from the
inventor at the PEAK Developers’ Center.
A freshly quickstarted project will have a setup.py file. This file allows
you to easily package your file for redistribution both for internal use and
for sharing on PyPI. Creating an egg is as simple as
switching to your project directory and running:
python setup.py bdist_egg
This will produce an egg file for the current version of your project in the
./dist folder.
Note
Please note that your .egg file cannot be installed in a .zip file, so you must always have “zip_safe=False” in your setup.py file. It needs to be in your setup call, so make sure to add it. If you don’t, and you install the egg, then your application will fail in numerous ways, including an inability to find templates, CSS files, JS files, everything. All you will see are 404 error messages. So please make sure to include it for your (and your users’) sakes. Thank you.
The simplest way to use an egg is to copy it over to your production machine and do:
[sudo] easy_install *myapp*.egg
Note
If you do not have easy_install on the target machine, you need
to install the setuptools package first to get it, either through your
operating system’s software package system or by downloading the
bootstrapping program ez_setup.py. Conveniently, ez_setup.py also
takes the same arguments that easy_install takes, so python
ez_setup.py *myapp*.egg will do the full install. Be sure to switch
over to easy_install after the first run.
As long as the setup.py lists TurboGears as a requirement (see the section
on adding requirements), it should be possible for somebody to install your
application with just the egg and easy_install or ez_setup.py including
the installation of TurboGears itself and all its dependencies.
Warning
This is a nice feature for application deployment, but be aware that installing an egg can also upgrade TurboGears and other packages if the egg requires a later version than the system provides. If long term system stability is important to you, you may want to investigate solutions like virtualenv.
Please be also aware that by default the setup.py file of a quickstarted
project will require a TurboGears version that is equal or newer than the
version which was used to run paster quickstart. This means if you
install your application and TurboGears is not installed or only an older
version than required, easy_install will fetch and install the newest
TurboGears version it can find. This includes beta versions and release
candidates of future TurboGears versions with a higher major version number.
If you want to ensure that your application will only install a known good
TurboGears version, you should add a more specific version constraint for
TurboGears in setup.py (again, see adding requirements on how to do this).
TurboGears apps take advantage of the paster serve functionality by providing a way to start the server as you would any other paste application
Once you have your application installed in the proper location simply cd to that location and type the following command:
$ paster serve production.ini
where production.ini is your production configuration file, which is covered in the
next section.
To get everything up and running, you also need a production configuration file
(usually called production.ini by convention) and pass the name of this file as the
first and only argument to your start script.
Your production configuration should specify location and parameters for the production database that your project will use.
This can be the same database as the one you created with paster setup-app
while developing your application. If you use a different database for production
(a wise decision) you will need to create the tables in the database, before using
it for the first time.
paster setup-app production.ini
will create the necessary tables using the database specified in the deployment
configuration file production.ini.
Once you are satisfied with the running of your server, it makes sense to run it in a background mode so that you may log off, leaving your server running. Paste does this with the –daemon argument. It looks something like this:
paster serve production.ini --daemon
To stop your application from running, simply type:
paster serve production.ini --stop-daemon
By specifying all your dependencies, not just TurboGears, easy_install can
completely automate your package setup. You specify dependencies by modifying
the requires argument in setup() in your setup.py file to include
the name of the package you need. Here is an example that adds the fictional
package FooBar as an installation requirement:
setup(
name="test",
version=0.1,
zip_safe=False,
install_requires = [
"TurboGears >= 2.1",
"FooBar"
],
...
If you need a specific version of the package you can use comparison operators against the version name. You can see that happening in the above example, as this project depends on “TurboGears version 2.1 or greater”. See the setuptools documentation for more information on declaring dependencies.
If you decide to share your creation with the world, the easiest way to do so is by using the Python Package Index. Before you can upload your project to PyPI, you will need an account. You can create one on the PyPI registration page.
After you have created an account, you will need to tell setuptools your account information for uploading the file. See the distutils documentation for details on this.
Now that you have your account configured and you’ve updated the metadata in
setup.py, you need to register a page for your application. setuptools
can do this for you automatically with the following command:
python setup.py register
Once you have everything configured, setuptools can upload your egg automatically. Here is the command you need:
python setup.py bdist_egg upload
Any eggs you created in the process should also be available in the dist/
folder of your project.
You can also register projects and upload your eggs manually. This setuptools tutorial should be enough to get you going.
Take a look at Generating your own Private Python Package Index to see how to make your own personal PYPI for distribution within a closed environment.