Using Environment Variables in Spring Boot Application.properties

In Spring Boot applications, there may be situations where you need to make database connection settings dynamic across different environments, such as local, testing, and production. One approach is to utilize environment variables and include them in the application.properties file.

To set up environment variables for different environments, follow these steps:

• Create System Environment Variables: Create system environment variables on your local machine and in the Jenkins VM with the same names as OpenShift uses. Assign appropriate values to these variables for each environment.
• Convert Environment Variables to Java Variables: Use System.getenv() to access these environment variables and convert them into Java variables like password, userName, sqlURL, and sqlPort.
• Include Environment Variables in application.properties: To use these variables in your application.properties file, include them as follows:

spring.datasource.url = ${OPENSHIFT_MYSQL_DB_HOST}:${OPENSHIFT_MYSQL_DB_PORT}/"nameofDB"
spring.datasource.username = ${OPENSHIFT_MYSQL_DB_USERNAME}
spring.datasource.password = ${OPENSHIFT_MYSQL_DB_PASSWORD}

However, a more preferred approach is to use Spring's profile mechanism and create separate application property files for each environment. Using the spring.profiles.active property, you can specify which profile should be active, and Spring will automatically load the corresponding property file.

This eliminates the need for explicit environment variable conversions and manages configuration files more effectively.