ConfigurationLoader

ConfigurationLoader is a flexible and powerful configuration management library for Java applications. Inspired by Spring Boot's configuration management but designed to work independently, this library provides a robust solution for applications requiring configuration outside of the Spring ecosystem.

Features

• Load configuration from multiple sources:
  • Properties files
  • YAML files
  • Environment variables
  • System properties
  • Command-line arguments
• Support for configuration profiles
• Hierarchical configuration with dot notation
• Placeholder resolution in configuration values
• Support for default values when using annotation
• Encryption and decryption of sensitive configuration values
• Annotation-based injection of configuration values

Getting Started

Prerequisites

• Java 11 or higher
• Maven or Gradle (for dependency management)

Installation

Add the following dependency to your pom.xml file:

<dependency>
    <groupId>ph.extremelogic.common.core.config</groupId>
    <artifactId>extremelogic-common-config</artifactId>
    <version>0.0.1</version>
</dependency>

Or for Gradle, add this to your build.gradle file: gradle

implementation 'ph.extremelogic.common.core.config:extremelogic-common-config:0.0.1'

Usage

Here's a simple example of how to use ConfigurationLoader:

1. Basic usage:

ConfigurationLoader loader = new ConfigurationLoader();
loader.loadConfiguration();

// Use the configuration
String host = loader.getProperty("app.mail-server.host");
int port = Integer.parseInt(loader.getProperty("app.mail-server.port"));

2. Using with annotations:

public class AppConfig {
    @ConfigurationLoader.Value("app.name")
    private String appName;

    @ConfigurationLoader.Value("app.version")
    private String appVersion;

    // getters and setters
}

ConfigurationLoader loader = new ConfigurationLoader();
loader.loadConfiguration();

AppConfig appConfig = new AppConfig();
loader.injectConfig(appConfig);

System.out.println("App Name: " + appConfig.getAppName());
System.out.println("App Version: " + appConfig.getAppVersion());

3. Loading YAML configuration:

ConfigurationLoader loader = new ConfigurationLoader();
loader.loadYaml();

String databaseUrl = loader.getProperty("database.url");
String databaseUsername = loader.getProperty("database.username");

Configuration Priority

The library loads configuration in the following order, with later sources overriding earlier ones:

1. Default properties file (config.properties)
2. Default YAML file (config.yml)
3. Profile-specific properties files (config-{profile}.properties)
4. Profile-specific YAML files (config-{profile}.yml)
5. Environment variables
6. System properties
7. Command-line arguments

Configuration Profiles

You can use configuration profiles to load environment-specific configurations. Set the active profile using:

• The config.profiles.active property in your default configuration file
• The CONFIG_PROFILES_ACTIVE environment variable
• The config.profiles.active system property
• The --config.profiles.active command-line argument

Encryption and Decryption

ConfigurationLoader supports encrypted property values. To use this feature:

1. Set the encryption key:

export CONFIG_ENCRYPTION_KEY=your-16-char-secret-key

or

java -Dconfig.encryption.key=your-16-char-secret-key -jar your-app.jar

2. Execute the main in the class DefaultPropertyEncryptor:

public static void main(String[] args) {
    var scanner = new Scanner(System.in);

    System.out.print("Enter a 16-character encryption key: ");
    String encryptionKey = scanner.nextLine();

    if (encryptionKey.length() != KEY_LENGTH) {
        System.out.println("Error: Encryption key must be 16 characters long.");
        return;
    }

    var encryptor = new PropertyEncryptor(encryptionKey);

    System.out.print("Enter a value to create an encrypted equivalent for your configuration: ");
    var valueToEncrypt = scanner.nextLine();

    var encryptedValue = encryptor.encrypt(valueToEncrypt);
    System.out.println();
    System.out.println("Place this in your configuration.");
    System.out.println("Encrypted Value: ENC(" + encryptedValue + ")");

    var decryptedValue = encryptor.decrypt(encryptedValue);
    System.out.println();
    System.out.println("Below is just a verification that we can decrypt it.");
    System.out.println("Decrypted Value: " + decryptedValue);
}

or

4. Use the jar to encrypt sensitive values:

You can run the JAR to generate the encrypted value for your configuration.

java -jar extremelogic-common-config-0.0.1.jar

When you run the JAR, it will prompt you to enter a 16-character encryption key and the value you want to encrypt. The encrypted value will be displayed in the following format:

Encrypted Value: ENC(encrypted-value-here)

5. Use encrypted values in your configuration files:

db.password=ENC(encrypted-value-here)

The ConfigurationLoader will automatically decrypt these values when loading the configuration.

Limitations

• The encryption key must be exactly 16 characters long.
• Placeholder resolution is currently limited to simple ${key} syntax and does not support nested placeholders.

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

License

This project is licensed under the Apache License 2.0 - see the LICENSE file for details.