spring.config.additional-location as environmental variable

Question

I have a Docker image for a spring boot 2 app, in the image I use spring.config.additional-location to pass a some properties stored in a file on the container itself.

Now I want to use this container in another as a layer in another container or use it in a docker-compose file and I may need to override the spring.config.additional-location.

I tried to override it in an ENV variable: SPRING_CONFIG_ADDITIONAL-LOCATION with no success.

What is the proper way to achieve this.

Answer 1

Value for spring.config.additional-location must be a directory path and not a file path. I'm not sure if this is a bug or a feature, since spring.config.location allows both.

For example inside docker-compose.yml you can set spring.config.additional-location as:

version: '3'
    services:
      myapp:
        build: .
        environment:      
          - "SPRING_CONFIG_ADDITIONAL-LOCATION=file:/opt/myapp/config/"
          - "SPRING_PROFILES_ACTIVE=production"
...

Then Spring Boot will look up for /opt/myapp/config/application-production.properties file to load properties from.

More about this in Spring Boot Externalized Configuration