Spring boot configure custom jsessionid for embedded server

Declare a ServletContextInitializer bean in your application's configuration:

@Bean
public ServletContextInitializer servletContextInitializer() {
    return new ServletContextInitializer() {

        @Override
        public void onStartup(ServletContext servletContext) throws ServletException {
            servletContext.getSessionCookieConfig().setName("yourCookieName");
        }
    };

}

Alternatively, your application class itself can implement ServletContextInitializer:

@Configuration
@EnableAutoConfiguration
@ComponentScan
public class Application implements ServletContextInitializer {

    public static void main(String[] args) throws Exception {
        SpringApplication.run(Application.class, args);
    }

    @Override
    public void onStartup(ServletContext servletContext) throws ServletException {
        servletContext.getSessionCookieConfig().setName("yourCookieName");
    }

}

with spring session , if you want to change cookie name ,you can do this

@Bean
public DefaultCookieSerializer defaultCookieSerializer(){
    DefaultCookieSerializer defaultCookieSerializer = new DefaultCookieSerializer();
    defaultCookieSerializer.setCookieName("mySessionId");
    return defaultCookieSerializer;
}

i find this in spring session source

spring-session-1.2.1.RELEASE-sources.jar!/org/springframework/session/config/annotation/web/http/SpringHttpSessionConfiguration.java

    @Autowired(required = false)
public void setCookieSerializer(CookieSerializer cookieSerializer) {
    this.defaultHttpSessionStrategy.setCookieSerializer(cookieSerializer);
}

As of Spring Boot 1.3 you can simply set a configuration property;

Spring Boot 1.3, 1.4, 1.5

server.session.cookie.name = MYSESSIONID

Spring Boot 2.x

server.servlet.session.cookie.name = MYSESSIONID

A lot simpler than writing a configuration class.

See https://docs.spring.io/spring-boot/docs/current/reference/html/common-application-properties.html for more session related properties.