Spring Boot 2.x - change session cookie id value length (JSESSIONID length in Tomcat server)

package com.example.config;

​

import org.apache.catalina.Context;

import org.apache.catalina.Manager;

import org.apache.catalina.SessionIdGenerator;

import org.apache.catalina.session.StandardManager;

import org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory;

import org.springframework.boot.web.server.WebServerFactoryCustomizer;

import org.springframework.context.annotation.Bean;

import org.springframework.context.annotation.Configuration;

​

@Configuration

public class TomcatConfig {

​

    @Bean

    public WebServerFactoryCustomizer<TomcatServletWebServerFactory> servletContainerCustomizer() {

        return (TomcatServletWebServerFactory container) -> {

            container.addContextCustomizers((Context context) -> {

                Manager manager = context.getManager();

                if (manager == null) {

                    context.setManager(manager = new StandardManager()); // if not defined before

                }

                SessionIdGenerator generator = manager.getSessionIdGenerator();

                // 32 bytes requires 64 characters to encode cookie value

                // by default, used session is length is 16 bytes

                generator.setSessionIdLength(32);

            });

        };

    }

}