How to resolve placeholder in properties file with values from another properties file in spring boot application

Question

My spring boot application has below properties files.

src/main/resources/config/DEV/env.properties
mail.server=dev.mail.domain

src/main/resources/config/QA/env.properties
mail.server=qa.mail.domain

src/main/resources/config/common/env.properties
mail.url=${mail.server}/endpoint

Is it possible to load "common/env.properties" so that it's placeholders will be resolved using the given environment specific properties file. For DEV environment, we want the placeholders in "common/env.properties" to be resolved using values from "DEV/env.properties".

There are answers about how to load multiple properties files and profile based loading but could not find an answer for this particular use case.

Thanks in advance.

Answer 1

2 Options :

1. Generate the common/application.properties using configuration-maven-plugin and filter files for each environment. It is outdated now.
2. Use application-<env>.properties for each environment and pass the -Dspring.profiles.active=<env> as VM option in application start up. Spring will automatically take the property from correct file.

In option 2, you will be overwriting whatever is present in application.properties with application-.properties. So you dont have to add only the properties which you need to change per environment.

for eg:

Your application.properties can have

logging.level.root=WARN
logging.level.org.apache=WARN
logging.level.org.springframework=WARN

Your application-dev.properties can have

logging.level.org.springframework=DEBUG

which means, when you are starting application using dev profile, spring takes

logging.level.root=WARN
logging.level.org.apache=WARN
logging.level.org.springframework=DEBUG

edit :

Also, you can try something like below on your class. (Spring will overwrite value in config.properties with values from config-dev.properties). ignoreResourceNotFound will make sure, application will still start with default values even if the corresponding file is not found.

@Configuration
@PropertySource("classpath:config.properties")
@PropertySource(value = "classpath:config-${spring.profiles.active}.properties", ignoreResourceNotFound = true)