Spring Boot: The embedded server port and context path

Port 0 asks the OS for a free port, which is how integration tests avoid clashing.

Code

// application.yml
server:
  port: 8080
  servlet:
    context-path: /api

// In a test:
@SpringBootTest(webEnvironment = RANDOM_PORT)
class ApiTest {
    @LocalServerPort int port;
}

Output

Tomcat started on port 8080 (http) with context path '/api'
In tests: a different free port every run, injected into the field.

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Published 2026-08-11