Spring boot configuration with environment variables

Question

I have a spring boot application which interacts with DB to provide resource using Spring data Rest. I want to get the configuration from environment variables. Below is my properties file.

spring.datasource.url=${mysql.url}
spring.datasource.username=${mysql.user}
spring.datasource.password=${mysql.password}

And my environment variables are in the image https://ibb.co/cyxsNc

I even tried with the below config too

spring.datasource.url=${MySQL_Url}
spring.datasource.username=${MySQL_User}
spring.datasource.password=${MySQL_Password}

But I am not able to connect to the DB and getting the below error

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration': Unsatisfied dependency expressed through constructor parameter 0; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dataSource' defined in class path resource [org/springframework/boot/autoconfigure/jdbc/DataSourceConfiguration$Tomcat.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.apache.tomcat.jdbc.pool.DataSource]: Factory method 'dataSource' threw exception; nested exception is java.lang.IllegalArgumentException: URL must start with 'jdbc'

Application folder structure

Project
|-- src/main/java
    |-- com.example.app
        |-- DemoApplication.java
|-- src/main/resources
    |-- application.properties

Note: The configuration works fine if I set the values like below

spring.datasource.url=jdbc:mysql://localhost:3306/ex_man
spring.datasource.username=root
spring.datasource.password=root

What am I missing?

Answer 1

Check out this documentation here: https://docs.spring.io/spring-boot/docs/current/reference/html/boot-features-external-config.html

try naming your environment variables:

SPRING_DATASOURCE_URL

SPRING_DATASOURCE_USERNAME

SPRING_DATASOURCE_PASSWORD

UPDATE:

Spring boot does properly pick up the environment variables, see test below.

package com.example.environment_vars;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;

import java.util.Map;      // Import this for systemEnvironment

@SpringBootApplication
public class EnvironmentVarsApplication {

    @Value("#{systemEnvironment['ENV_VAR'] ?: 'Default_value'}")
    private String envVar;
    
    @Bean
    public CommandLineRunner commandLineRunner() {
        return new CommandLineRunner() {
            @Override
            public void run(String[] arg0) throws Exception {
                System.out.println(envVar);
            }
        };
    }
    
    public static void main(String[] args) {
        SpringApplication.run(EnvironmentVarsApplication.class, args);
    }
}

This will print out the value of the environment variable ENV_VAR and if the value is not present, it will print the Default_Value.

@Value injects the value accessible throughout the project.