How to prevent Redis writes for anonymous user sessions - spring-boot

Question

I have this sample application:
package com.example.session;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Configuration;
import org.springframework.security.config.annotation.authentication.builders.AuthenticationManagerBuilder;
import org.springframework.security.config.annotation.web.builders.HttpSecurity;
import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;
import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter;
import org.springframework.session.data.redis.config.annotation.web.http.EnableRedisHttpSession;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
#SpringBootApplication
public class DemoRedisDataSessionApplication {
#Configuration
#EnableWebSecurity
#EnableRedisHttpSession(redisNamespace = "demo-redis-data-session")
public static class AppConfiguration extends WebSecurityConfigurerAdapter {
#Override
protected void configure(AuthenticationManagerBuilder auth) throws Exception {
auth.inMemoryAuthentication().withUser("user").password("0000").roles("USER");
}
#Override
protected void configure(HttpSecurity http) throws Exception {
http.formLogin().and()
.authorizeRequests().antMatchers("/ping").permitAll().and()
.authorizeRequests().anyRequest().fullyAuthenticated();
}
}
#RestController
public static class AppController {
#GetMapping("/ping")
public String ping() {
return "pong";
}
#GetMapping("/secured")
public String secured() {
return "secured";
}
}
public static void main(String[] args) {
SpringApplication.run(DemoRedisDataSessionApplication.class, args);
}
}
When I hit /secured I get 302 redirected to the /login form, which is what I expect if I am not logged in, but I get some unwanted entries in Redis:
127.0.0.1:6379> keys *
1) "spring:session:demo-redis-data-session:sessions:expires:dbb124b9-c37d-454c-8d67-409f28cb88a6"
2) "spring:session:demo-redis-data-session:expirations:1515426060000"
3) "spring:session:demo-redis-data-session:sessions:dbb124b9-c37d-454c-8d67-409f28cb88a6"
I don't want to create this data for every anonymous user (read crawler), so is there a way to prevent these Redis entries when hitting a secured endpoint/page with an anonymous user?
Additional data used for this sample project
 docker-compose.yml
version: "2"
services:
redis:
image: redis
ports:
- "6379:6379"
Spring Boot version
1.5.9.RELEASE

Answer 1

This is not the optimal solution since it creates only one session for all crawlers, but at least I don't get Redis full of unwanted session.
import lombok.extern.log4j.Log4j;
import org.springframework.session.Session;
import org.springframework.session.SessionRepository;
import org.springframework.session.web.http.CookieHttpSessionStrategy;
import org.springframework.session.web.http.MultiHttpSessionStrategy;
import org.springframework.stereotype.Component;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
#Log4j
#Component
public class CrawlerManagerSessionStrategyWrapper implements MultiHttpSessionStrategy {
private CookieHttpSessionStrategy delegate;
private volatile String crawlerSessionId;
public CrawlerManagerSessionStrategyWrapper() {
this.delegate = new CookieHttpSessionStrategy();
}
public String getRequestedSessionId(HttpServletRequest request) {
String sessionId = getSessionIdForCrawler(request);
if (sessionId != null)
return sessionId;
else {
return delegate.getRequestedSessionId(request);
}
}
public void onNewSession(Session session, HttpServletRequest request, HttpServletResponse response) {
delegate.onNewSession(session, request, response);
if (isCrawler(request)) {
crawlerSessionId = session.getId();
}
}
public void onInvalidateSession(HttpServletRequest request, HttpServletResponse response) {
delegate.onInvalidateSession(request, response);
}
public HttpServletRequest wrapRequest(HttpServletRequest request, HttpServletResponse response) {
return request;
}
public HttpServletResponse wrapResponse(HttpServletRequest request, HttpServletResponse response) {
return response;
}
private String getSessionIdForCrawler(HttpServletRequest request) {
if (isCrawler(request)) {
SessionRepository<Session> repo = (SessionRepository<Session>) request.getAttribute(SessionRepository.class.getName());
if (crawlerSessionId != null && repo != null) {
Session session = repo.getSession(crawlerSessionId);
if (session != null) {
return crawlerSessionId;
}
}
}
return null;
}
private boolean isCrawler(HttpServletRequest request) {
// Here goes the logic to understand if the request comes from a crawler, for example by checking the user agent.
return true;
}
}
The only thing to implement is the isCrawler method to state if the request comes from a crawler.