Configuration environment properties of SpringBoot

Configuration environment properties of SpringBoot

In this article, we'll discuss Spring Boot's configuration environment properties. We'll see how to use these properties to configure our application to run in different environments. We'll also see how to manage these properties using Spring Boot's configuration files. Finally, we'll cover some best practices to help you use these properties more effectively.

Understand SpringBoot's configuration environment properties

Spring Boot's configuration environment properties are a set of key-value pairs used to configure the application. These properties can be used to control the behavior of the application, such as database connections, log levels, etc. The configuration environment properties of SpringBoot can be defined in multiple sources, such as application.propertiesfiles, environment variables, command line parameters, etc.

Spring Boot's configuration environment properties follow a hierarchical structure, which means that properties defined in different sources can override each other. For example, if application.propertiesa property is defined in a file, but the same property is also defined in an environment variable, the value in the environment variable will override the application.propertiesvalue in the file.

Using application.propertiesfile configuration properties

application.propertiesfile is the default configuration file for SpringBoot applications. It is located under the project's src/main/resourcesdirectory. In this file we can define our configuration properties to be used in the application.

Here is a simple application.propertiesfile example:

spring.datasource.url=jdbc:mysql://localhost:3306/mydb
spring.datasource.username=myuser
spring.datasource.password=mypassword

In this example, we define the URL, username and password for the database connection. These properties will be used in our application to configure the data source.

Configure Properties Using Environment Variables and Command-Line Arguments

In addition to using application.propertiesfiles, we can also use environment variables and command line arguments to configure our application. This is useful in some cases, for example when deploying an application to production where we may not want to store sensitive information such as database passwords in configuration files.

To configure properties using environment variables, we can set environment variables before launching the application. For example, we can execute the following commands on the command line:

export SPRING_DATASOURCE_URL=jdbc:mysql://localhost:3306/mydb
export SPRING_DATASOURCE_USERNAME=myuser
export SPRING_DATASOURCE_PASSWORD=mypassword

We can then use these environment variables as configuration properties in our application.

To configure properties using command line arguments, we can pass arguments when starting the application. For example, we can execute the following command:

java -jar myapp.jar --spring.datasource.url=jdbc:mysql://localhost:3306/mydb --spring.datasource.username=myuser --spring.datasource.password=mypassword

In this example, we --passed command line arguments using prefix. These parameters will be used as configuration properties in the application.

Using SpringBoot's configuration file management properties

In some cases, we may need to use different configuration properties in different environments. For example, we may wish to use one database in the development environment and another database in the production environment. In order to achieve this, we can use SpringBoot configuration files.

SpringBoot configuration files are a special type of application.propertiesfile that can load different properties based on the current environment. The names of configuration files follow the format:

application-{profile}.properties

where {profile}is the name of the environment. For example, we can create a application-dev.propertiesfile named , which stores configuration properties for the development environment. We can then activate this profile when launching the application like so:

java -jar myapp.jar --spring.profiles.active=dev

In this example, we spring.profiles.activeactivated devthe configuration file using a property. This will cause the application to load application-dev.propertiesthe properties in the file.

Priority of configuration files

When SpringBoot loads configuration files, it will find and load these files in a certain order of priority. The following is the order in which SpringBoot looks for configuration files:

1. ./configSubdirectories under the current directory
2. Current directory
3. /configpackages on the classpath
4. classpath root

In this order, higher-priority configuration files override properties in lower-priority configuration files.

Annotated with @ConfigurationProperties

We can @ConfigurationPropertiesbind properties in configuration files to Java classes using annotations. This way, we can use these properties in our application. Here is an example:

import org.springframework.boot.context.properties.ConfigurationProperties;

@ConfigurationProperties(prefix = "spring.datasource")
public class DataSourceProperties {
    
    
    private String url;
    private String username;
    private String password;

    // getters and setters
}

In this example, we use @ConfigurationPropertiesannotations to spring.datasourcebind prefixed properties to DataSourcePropertiesclasses.

Use the @Profile annotation

We can use @Profileannotations to define beans that are activated in a specific environment. For example, we can define different data source configurations for development and production environments. Here is an example:

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Profile;

@Configuration
public class DataSourceConfig {
    
    

    @Bean
    @Profile("dev")
    public DataSource devDataSource() {
    
    
        // configure dev data source
    }

    @Bean
    @Profile("prod")
    public DataSource prodDataSource() {
    
    
        // configure prod data source
    }
}

In this example, we @Profiledefine two different data source configurations using annotations. Depending on the activated environment configuration, the corresponding data source will be used.

Best practice for SpringBoot configuration environment properties

Here are some best practices for configuring environment properties with Spring Boot:

1. Whenever possible, use application.propertiesfiles to store common configuration properties. This will make your application easier to maintain and understand.
2. Avoid storing sensitive information such as database passwords in configuration files. Instead, use environment variables or command-line arguments to pass this information.
3. Use SpringBoot's configuration files to manage configuration properties for different environments. This will make your application easier to deploy and run in different environments.
4. When defining configuration properties, follow SpringBoot's naming conventions. This will make your properties easier to understand and use.

In short, SpringBoot's configuration environment properties are a powerful tool that can help us configure and manage our applications. By following the best practices described in this article, you can use these properties more effectively to build maintainable and scalable applications.