Configuration Variables

Your Glashammer application has automatic configuration built in. It doesn’t actually need a configuration file, and if Glashammer doesn’t find one, the default values are used.

Glashammer will search for a config file called “config.ini” in the instance directory of your application. If this file is found Glashammer will use it to override the default settings. This file is a human-writable/readable ini-style file which is designed to be able to be edited by hand if required.

Configuration variables can generally be one of the python types:

• str
• int
• bool

Adding a configuration value

During the application setup phase, config variables can be added using:

GlashammerApplication.add_config_var(key, type, default)

Add a configuration variable to the application.

So for example a simple configuration variable for whether the application is in maintenance mode might be added like:

app.add_config_var('maintenance_mode', bool, False)

Reading configuration variables

A configuration variable can be read after application setup durin the request phase by using the app.conf as a dict-like item.

For example:

if app.conf['maintenance_mode']:
    # the application is in maintenance mode
    return redirect('/maintenance')

Setting a configuration variable

You can set configuration variables using the set method of the configuration object:

Configuration.change_single(key, value)

Create and commit a transaction for a single key-value-pair. Return True on success, otherwise False.

This method ensures that the value is changed and written in a transaction to avoid concurrency issues. So to continue our example, to set the ‘maintenance_mode’ variable:

app.conf.change_single('maintenance_mode', True)

Other backends

Currently only a file-based configuration backend exists, but this can be non-ideal in some situations. For example, when using Google AppEngine, the configuration file will have to be created offline and uploaded, and the configuration will not be able to be changed from the running app.

For these kinds of reasons, we encourage developers to come up with alternative backends which solve these kinds of problems. The interface is relatively simple, so the task should be simple.