This tutorial details the best practices for automatically redirecting HTTP requests to HTTPS in Spring Boot 2.7.x applications. The article comparatively analyzes the limitations of Spring Security's portMapper mechanism in redirection, and focuses on implementing an efficient and reliable server-level redirection solution by configuring the embedded Tomcat Connector, and provides complete code examples and precautions.

introduction

In modern web application development, the mandatory use of HTTPS has become an industry standard to ensure data security and user trust. Spring Boot applications usually run through an embedded Tomcat or Jetty server, and configuring HTTP requests to automatically redirect to HTTPS is a common need. Although Spring Security provides configurations such as requiresChannel().anyRequest().requiresSecure() and portMapper() to enforce secure channels, in some cases these configurations may not directly implement the intended browser-level redirection of HTTP to HTTPS. This tutorial will delve into this issue and provide a robust solution based on Tomcat Connector.

Spring Security requiresChannel and portMapper mechanism analysis

Spring Security provides powerful security mechanisms, including the ability to enforce the use of secure channels. By adding requiresChannel().anyRequest().requiresSecure() to the SecurityFilterChain configuration, you can ensure that all requests must be accessed over HTTPS.

The following is a common Spring Security configuration snippet in a Spring Boot application:

 package tacos.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.security.config.annotation.method.configuration.EnableGlobalMethodSecurity;
import org.springframework.security.config.annotation.web.builders.HttpSecurity;
import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;
import org.springframework.security.core.userdetails.UserDetailsService;
import org.springframework.security.core.userdetails.UsernameNotFoundException;
import org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder;
import org.springframework.security.crypto.password.PasswordEncoder;
import org.springframework.security.web.SecurityFilterChain;
import tacos.model.User;
import tacos.repository.UserRepository;

@Configuration
@EnableGlobalMethodSecurity(prePostEnabled = true)
@EnableWebSecurity
public class SecurityConfig {

    @Bean
    public PasswordEncoder passwordEncoder(){
        return new BCryptPasswordEncoder();
    }

    @Bean
    public UserDetailsService userDetailsService(UserRepository userRepository){
        return username -> {
            User user = userRepository.findByUsername(username);
            if (user != null) return user;
            throw new UsernameNotFoundException("User " username "not found");
        };
    }

    @Bean
    public SecurityFilterChain filterChain(HttpSecurity httpSecurity) throws Exception{
        return httpSecurity.authorizeRequests()
                .antMatchers("/design","/orders","/orders/*").hasRole("USER")
                .antMatchers("/", "/**").permitAll()
                .antMatchers("/h2-console/**").permitAll()
                .and()
                .csrf().ignoringAntMatchers("/h2-console/**")
                .and()
                .headers().frameOptions().sameOrigin()
                .and()
                .formLogin().loginPage("/login")
                .loginProcessingUrl("/authenticate")
                .usernameParameter("user")
                .passwordParameter("pwd")
                .defaultSuccessUrl("/design", true)
                .and()
                .oauth2Login().loginPage("/login")
                .and()
                .logout()
                .and()
                .requiresChannel().anyRequest().requiresSecure() // Force all requests to use a secure channel.and()
                .portMapper().http(8080).mapsTo(8443) // Map HTTP to HTTPS port.and().build();
    }
}

In the above configuration:

• requiresChannel().anyRequest().requiresSecure() instructs Spring Security that only requests over a secure channel (HTTPS) will be processed. If a non-secure (HTTP) request is received, Spring Security will attempt to redirect it to the appropriate secure URL.
• The role of portMapper().http(8080).mapsTo(8443) is to tell Spring Security that when requests for HTTP port 8080 need to be redirected to HTTPS, port 8443 should be used.

Although requiresChannel triggers a redirect, this redirection is handled by Spring Security in its filter chain. In some deployment environments or configurations, this approach may not provide a seamless, direct HTTP to HTTPS browser redirection experience at the Tomcat server level. More direct server-level redirection is usually done in the Web server's connector configuration.

HTTP to HTTPS redirection based on Tomcat Connector

The most straightforward and recommended way to implement HTTP to HTTPS redirection is to configure the Connector of the embedded Tomcat server. This method completes the redirection at the Tomcat level before the request reaches the Spring Security filter chain, thus providing a more efficient and reliable redirection mechanism.

Here is a code example that implements this functionality:

 package tacos.config;

import org.apache.catalina.Context;
import org.apache.catalina.connector.Connector;
import org.apache.tomcat.util.descriptor.web.SecurityCollection;
import org.apache.tomcat.util.descriptor.web.SecurityConstraint;
import org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory;
import org.springframework.boot.web.servlet.server.ServletWebServerFactory;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class TomcatConfig {

    /**
     * Configure the embedded Tomcat server and add an HTTP connector for redirection.
     * @return configured ServletWebServerFactory
     */
    @Bean
    public ServletWebServerFactory servletContainer() {
        // Create a TomcatServletWebServerFactory instance TomcatServletWebServerFactory tomcat = new TomcatWebServerFactory() {
            @Override
            protected void postProcessContext(Context context) {
                //Add security constraints SecurityConstraint for all URL patterns securityConstraint = new SecurityConstraint();
                securityConstraint.setUserConstraint("CONFIDENTIAL"); // Require the use of secure transmission SecurityCollection collection = new SecurityCollection();
                collection.addPattern("/*"); // Match all paths securityConstraint.addCollection(collection);
                context.addConstraint(securityConstraint);
            }
        };
        // Add an additional HTTP connector for redirecting to HTTPS
        tomcat.addAdditionalTomcatConnectors(redirectConnector());
        return tomcat;
    }

    /**
     * Create an HTTP connector and configure it to redirect requests to the HTTPS port.
     * @return configured Connector instance*/
    private Connector redirectConnector() {
        Connector connector = new Connector("org.apache.coyote.http11.Http11NioProtocol");
        connector.setScheme("http"); //Set the connector protocol to HTTP
        connector.setPort(8080); // Listen to HTTP port 8080
        connector.setSecure(false); // Mark the connector as non-secure connector.setRedirectPort(8443); // Redirect all HTTP requests to HTTPS port 8443
        return connector;
    }
}

Code analysis

1. servletContainer() Bean:

   • This method returns a ServletWebServerFactory instance, which Spring Boot will use to create and configure the embedded web server.
   • We used TomcatServletWebServerFactory and overridden the postProcessContext() method.
   • In postProcessContext(), we create a SecurityConstraint. setUserConstraint("CONFIDENTIAL") forces all matching requests to be transmitted over a secure channel (HTTPS). SecurityCollection is configured with addPattern("/*"), which means that this constraint applies to all paths in the application. When Tomcat receives a non-secure (HTTP) request that matches a CONFIDENTIAL constraint, it attempts to redirect it to the Connector's configured redirectPort.
   • tomcat.addAdditionalTomcatConnectors(redirectConnector()) is the key step. It tells Tomcat to create an additional HTTP connector in addition to the default connector (usually the HTTPS connector if SSL is configured).

2. redirectConnector() method:

   • This private method creates and configures an org.apache.catalina.connector.Connector instance.
   • connector.setScheme("http") and connector.setPort(8080): Clearly indicate that this is an HTTP connector listening on port 8080.
   • connector.setSecure(false): Mark it as a non-secure connector.
   • connector.setRedirectPort(8443): This is the core of redirection. When Tomcat receives a request through this HTTP connector (port 8080), and the request requires secure transmission (defined by SecurityConstraint), it automatically redirects the request to port 8443.

Things to note

1. SSL/TLS certificate configuration:

   • The above redirection scheme requires that your Spring Boot application has been correctly configured for HTTPS. This is usually done by configuring the SSL certificate in application.properties or application.yml:

    #application.properties
   server.port=8443
   server.ssl.key-store=classpath:keystore.p12
   server.ssl.key-store-password=your_password
   server.ssl.key-store-type=PKCS12
   server.ssl.key-alias=your_alias

2. Port conflict:

   • Make sure that ports 8080 and 8443 are not occupied by other applications.
   • If the default HTTPS port of your Spring Boot application is not 8443, please change the setRedirectPort() value in redirectConnector() to the actual HTTPS port.

3. External proxy/load balancer:

   • If your application is deployed behind Nginx, Apache, or other load balancer/reverse proxy, these proxies will typically handle HTTP to HTTPS redirection. In this case, you may not need to configure the above configuration inside the Spring Boot application. The proxy server forwards all HTTP requests to the application's HTTPS port.

4. Spring Boot version compatibility:

   • The examples in this tutorial are based on Spring Boot 2.7.x. For other versions, the core concepts remain the same, but the specific class names or configuration methods may differ slightly.

5. pom.xml dependencies:

   • Make sure your pom.xml includes the spring-boot-starter-web dependency as it will introduce embedded Tomcat.

    <dependency>
       <groupid>org.springframework.boot</groupid>
       <artifactid>spring-boot-starter-web</artifactid>
   </dependency>

Summarize

In Spring Boot 2.7.x applications, it is a direct and efficient method to implement HTTP to HTTPS redirection by configuring the embedded Tomcat Connector. It handles redirects at the server level, providing lower-level control and more reliable behavior than Spring Security portMapper. Combined with SecurityConstraint, this approach ensures that all non-secure requests are forcibly redirected to the secure channel. Be sure to configure SSL/TLS certificates correctly and consider deploying an external proxy or load balancer in your environment to avoid duplicate or conflicting redirect rules.

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