Load spring boot app properties from database

Question

I need you to advice me with this issue, in a spring boot application I load some properties from database like (cron periods, email data), I need to export these properties

Answer 1

For those who need load properties from database before application starts, and make those props accesible by @Value anywhere in your project, just add this processor.

public class ReadDbPropertiesPostProcessor implements EnvironmentPostProcessor {
/**
 * Name of the custom property source added by this post processor class
 */
private static final String PROPERTY_SOURCE_NAME = "databaseProperties";

private String[] KEYS = {
        "excel.threads",
        "cronDelay",
        "cronDelayEmail",
        "spring.mail.username",
        "spring.mail.password",
        "spring.mail.host",
        "spring.mail.port",
        "spring.mail.properties.mail.transport.protocol",
        "spring.mail.properties.mail.smtp.auth",
        "spring.mail.properties.mail.smtp.starttls.enabled",
        "spring.mail.properties.mail.debug",
        "spring.mail.properties.mail.smtp.starttls.required",
        "spring.mail.properties.mail.socketFactory.port",
        "spring.mail.properties.mail.socketFactory.class",
        "spring.mail.properties.mail.socketFactory.fallback",
        "white.executor.threads",
        "white.search.threads",
        "lot.sync.threads",
        "lot.async.threads",
        "lot.soap.threads",
        "excel.async.threads",
        "kpi.threads",
        "upload.threads"
};

/**
 * Adds Spring Environment custom logic. This custom logic fetch properties from database and setting highest precedence
 */
@Override
public void postProcessEnvironment(ConfigurableEnvironment environment, SpringApplication application) {

    Map propertySource = new HashMap<>();

    try {

        // Build manually datasource to ServiceConfig
        DataSource ds = DataSourceBuilder
                .create()
                .username(environment.getProperty("spring.datasource.username"))
                .password(environment.getProperty("spring.mail.password"))
                .url(environment.getProperty("spring.datasource.url"))
                .driverClassName("com.mysql.jdbc.Driver")
                .build();

        // Fetch all properties

        Connection connection = ds.getConnection();

        JTrace.genLog(LogSeverity.informational, "cargando configuracion de la base de datos");

        PreparedStatement preparedStatement = connection.prepareStatement("SELECT value FROM config WHERE id = ?");

        for (int i = 0; i < KEYS.length; i++) {

            String key = KEYS[i];

            preparedStatement.setString(1, key);

            ResultSet rs = preparedStatement.executeQuery();

            // Populate all properties into the property source
            while (rs.next()) {
                propertySource.put(key, rs.getString("value"));
            }

            rs.close();
            preparedStatement.clearParameters();

        }

        preparedStatement.close();
        connection.close();

        // Create a custom property source with the highest precedence and add it to Spring Environment
        environment.getPropertySources().addFirst(new MapPropertySource(PROPERTY_SOURCE_NAME, propertySource));

    } catch (Throwable e) {
        throw new RuntimeException(e);
    }
}
} // class ReadDbPropertiesPostProcessor end

In application.properties must exist datasource data in order to be able to connect to database.

Then in folder META-INF create a file named spring.factories an there put the following line:

org.springframework.boot.env.EnvironmentPostProcessor=test.config.ReadDbPropertiesPostProcessor

And that's it, retreived properties will be accessible anywhere.