The official document in SpringBoot is called Externalized Configuration:

The priorities are as follows:

(1) Devtools global settings properties in the $HOME/.config/spring-boot folder when devtools is active.

(2) @TestPropertySource annotations on your tests.

(3) properties attribute on your tests. Available on @SpringBootTest and the test annotations for testing a particular slice of your application.

(4) Command line arguments.

(5) Properties from SPRING_APPLICATION_JSON (inline JSON embedded in an environment variable or system property).

(6) ServletConfig init parameters.

(7) ServletContext init parameters.

(8) JNDI attributes from java:comp/env.

(9) Java System properties (System.getProperties()).

(10) OS environment variables.

(11) A RandomValuePropertySource that has properties only in random.*.

(12) Profile-specific application properties outside of your packaged jar (application-{profile}.properties and YAML variants).

(13) Profile-specific application properties packaged inside your jar (application-{profile}.properties and YAML variants).

(14) Application properties outside of your packaged jar (application.properties and YAML variants).

(15) Application properties packaged inside your jar (application.properties and YAML variants).

(16) @PropertySource annotations on your @Configuration classes. Please note that such property sources are not added to the Environment until the application context is being refreshed. This is too late to configure certain properties such as logging.* and spring.main.* which are read before refresh begins.

(17) Default properties (specified by setting SpringApplication.setDefaultProperties).

In run as Configuration, the program argument is set to server.port=8001

Environment Set the Environment variable to server.port=8002.

The Application. Properties file inside the SpringBoot project is set to 8000:

When finally run, port 8002 is set to the environment variable:

Using the set command in the shell to set environment variables also works as expected:

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