Override spring-boot application configuration via external property file

Question

I want to override few configurations in my spring boot application during a restart via an external configuration file.

What I am using: java -jar -Dspring.profiles.active=${ENV} my-application.jar

This loads my profile specific application property during application start. Let's assume I have an issue and I need to change the configuration in my application, I don't want to rebuild my application again with the changed property, what I want to achieve is that I provide an external property file which has the new value for the configuration and I restart my application.

I have tried suggestion mentioned here https://docs.spring.io/spring-boot/docs/current/reference/htmlsingle/#boot-features-external-config-application-property-files

Let's say I copy my jar to bin folder on my server and create a /config folder inside the bin folder which contains the override.properties file and then run the same command as stated above to restart my application.

It doesn't override the property mentioned in override.properties

I tried to provide spring.config.location as a command line argument but then I need to write all my properties in that file which is not what I need.

Answer 1

If you look at the top of Section 24 in the link you cite, you'll see a long list of places that Spring looks for property providers. Have you looked down that list? There are a number of options for providing external properties that override internal ones. Basically, anything higher on the list will override something lower on the list.

One option is to put JSON in the single environment variable SPRING_APPLICATION_JSON. This is what we do for unexpected overrides. We always define this variable in a separate file included by our main startup script, but it is usually empty. But at any time, we can go and add properties to it, and they will take priority and override any existing property values. We chose this option because it has a vey high priority. It is mostly only test code and settings that override these settings. The only other thing that does is properties put on the command line. Those, of course, can be changed without building a new binary.

There are other promising choices on that list, like #14. I believe there are ways of having external properties files that don't replace existing ones, but rather just override them, so that you don't have to redefine all of your existing properties there. I'd be surprised if there was no way to do that...have an external properties file that just overrode a few properties.

UPDATE: The "duplicate" cited in the question comments backs up what I'm saying here. It says very clearly that multiple properties files will override each other. No one file need provide all the properties. So it seems you're on the right track, and just have something wrong with your properties file configuration. Just keep in mind what I'm saying. It may be easier to use some other source than a properties file, like either the single environment variable SPRING_APPLICATION_JSON, or individual environment variables.