Spring boot is not able to read docker-compose environmental variables - spring-boot

Question

I am having a "boring" problem here. Let me explain...
I am trying read some 'environmental variables' from my docker-compose, in my Application.properties.
Although, I am creating properly the env's variables in the containers(I can see that when I inspect the containers), they are not being read from the spring boot Applications.
Its kinda, these 'docker-compose environmental variables', seems like "are not accessible".
I am doing a TEST (); so, I am trying to get an environmental variable in my Spring Application, and it's resulting in 'null', such as:
#Slf4j
#SpringBootApplication(exclude = R2dbcAutoConfiguration.class)
public class AppDriver {
public static void main(String[] args) {
System.out.println( "container variables >>>>> " + System.getenv("MASTER_URL") );
SpringApplication.run(AppDriver.class,args);
}
The log is:
conteiner variables >>>>> null
Below, They are my docker-compose (i do not have any Spring boot service in the docker-compose[for now]):
version: "3.5"
services:
tenant1:
image: postgres
ports:
- "5432:5432"
restart: always
environment:
POSTGRES_PASSWORD: password
POSTGRES_DB: tenant1
POSTGRES_USER: user
volumes:
- ./data/tenant1:/var/lib/postgresql
mysql:
image: mysql:5.7
ports:
- "3306:3306"
environment:
MASTER_URL: r2dbc:mysql://user:password#localhost/master
MYSQL_ROOT_PASSWORD: mysecret
MYSQL_USER: user
MYSQL_PASSWORD: password
MYSQL_DATABASE: master
My Application.properties:
logging.level.com.example=DEBUG
logging.level.io.r2dbc=DEBUG
master.url = ${MASTER_URL}
And finally, my Java File:
#Configuration
//#ConfigurationProperties(prefix = "master")
#EnableR2dbcRepositories(entityOperationsRef = "masterEntityTemplate")
public class MasterConfig {
#Value("${master.url}")
private String url;
#Bean
#Qualifier(value = "masterConnectionFactory")
public ConnectionFactory masterConnectionFactory() {
System.out.println(">>>>>>>>>>>" + url);
return ConnectionFactories.get(url);
//.get("r2dbc:mysql://user:password#localhost/master");
}
Thats the final error I am taking:
Caused by: java.lang.IllegalArgumentException: Could not resolve placeholder 'MASTER_URL' in value "${MASTER_URL}"
Someone know how to solve this problem?
Thanks a lot