AppConfig is a small configuration library which provides properties for applications deployed to different environments. For example, your local file storage is located at /home/joe/project1/files in a development environment (laptop), but in production it is located on the NFS: /opt/project1/files.

AppConfig makes it easy to configure multiple property files, one per environment and load just one depending what environment the application is running on.

As such, you may have a property file with content:


while the file will include:


Reading properties

First, import a static import AppConfig.p(...) method:

then, simply call it as: p(..) in places where you need to inject a property:

Property substitution

AppConfig allows a property substitution to make it possible to refactor large property files by specifying a repeating value once.

If your property file has these properties:
phrase= And the name is ${}

than this code will print And the name is John:

Note: The order of properties does not matter.

Setting an environment

AppConfig allows configuration of applications that is specific for different deployment environments. Applications have environment-specific files, whose names follow this pattern:, where environment is a name of a deployment environment, such as development, staging, production, etc.

You can also provide a global file, properties from which will be loaded in all environments:

In all cases the files need to be on the classpath under directory/package /app_config.

Environment-specific file will have an environment part of the file name match to an environment variable called ACTIVE_ENV. Such configuration is easy to achieve in Unix shell:

A typical file structure


Global property file will always be loaded, while others will be loaded depending on the value of `ACTIVE_ENV`` environment variable.

If environment variable ACTIVE_ENV is missing, AppConfig defaults to environment development.

System property override

You can also provide an environment as a system property

Here is an example (add this to the startup script for your app):

The system property points to a file specific to that computer (local box, server, etc.). If a specific property is provided in the properties file loaded on classpath, and the same property is also found in the file, then the value loaded from a local file overrides the one loaded from classpath.

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