How to Enable HTTP/2 in Spring Boot

Introduction

Enabling HTTP/2 in a Spring Boot application can significantly enhance performance by allowing multiple streams of data to be sent concurrently over a single TCP connection. This is especially beneficial for web applications that require high efficiency and low latency. HTTP/2 also minimizes protocol overhead by compressing header fields and enabling server push, where the server can send resources to a client without an explicit request from that client. This guide will cover how to enable HTTP/2 in Spring Boot, including possible solutions with sample code, outputs, and their advantages and disadvantages.

Solution

Enabling HTTP/2 in Spring Boot

Spring Boot makes it relatively straightforward to enable HTTP/2 support. However, the steps to achieve this can vary depending on the web server in use, such as Tomcat, Jetty, Reactor Netty, or Undertow. Below are the steps for different servers, along with the potential advantages and disadvantages.

HTTP/2 with Tomcat

Sample Code

Add the following properties to your application.properties or application.yml file:

server.http2.enabled=true
spring.main.web-application-type=reactive
server.port=8443
server.ssl.key-store=classpath:keystore.p12
server.ssl.key-store-password=secret
server.ssl.key-password=another-secret

Output
With HTTP/2 enabled, you can observe the use of HTTP/2 from the browser’s developer tools under the “Network” tab, where the “Protocol” column will show h2.

Advantages:

• Tomcat is widely used and well-documented.
• Default support in Spring Boot for HTTP/2 on JDK 9 or later.

Disadvantages:

• Requires configuration with SSL to take full advantage of HTTP/2.
• Additional setup may be needed for older versions of the JDK (e.g., JDK 8) to support ALPN.

HTTP/2 with Jetty

Sample Code

First, add the necessary dependencies to your build.gradle or pom.xml:

// build.gradle
implementation 'org.eclipse.jetty.http2:http2-server:9.4.35.v20201120'

Then, enable HTTP/2 in your application.properties or application.yml file:

server.http2.enabled=true
spring.main.web-application-type=reactive
server.port=8443
server.ssl.key-store=classpath:keystore.p12
server.ssl.key-store-password=secret
server.ssl.key-password=another-secret

Output
Similar to Tomcat, you can verify the use of HTTP/2 via the browser’s developer tools.

Advantages:

• Jetty supports HTTP/2 with additional libraries.
• Flexibility in configuration options.

Disadvantages:

• Requires extra dependencies and configurations.
• Slightly more complex setup compared to Tomcat.

HTTP/2 with Reactor Netty

Sample Code

Add necessary dependencies in your build.gradle:

implementation 'io.projectreactor.netty:reactor-netty-http:1.0.0'
implementation 'io.netty:netty-tcnative-boringssl-static:2.0.30.Final'

Then enable HTTP/2 in your application.properties:

server.http2.enabled=true
spring.main.web-application-type=reactive
server.port=8443
server.ssl.key-store=classpath:keystore.p12
server.ssl.key-store-password=secret
server.ssl.key-password=another-secret

Output
As with other servers, you can check the protocol being used in the network monitoring tools of your browser.

Advantages:

• Optimized for reactive programming.
• Simple configuration if using Spring WebFlux.

Disadvantages:

• Requiring native libraries for optimal performance on JDK 8.
• Not as mature as Tomcat or Jetty in terms of configuration options.

HTTP/2 with Undertow

Sample Code

Add Undertow to your build.gradle:

implementation 'org.springframework.boot:spring-boot-starter-undertow'
implementation 'org.springframework.boot:spring-boot-starter-webflux'

Configure HTTP/2:

server.http2.enabled=true
spring.main.web-application-type=reactive
server.port=8443
server.ssl.key-store=classpath:keystore.p12
server.ssl.key-store-password=secret
server.ssl.key-password=another-secret

Output
Verification remains the same via developer tools in the browser.

Advantages:

• Simple configuration.
• No additional requirements for HTTP/2 support on JDK 8.

Disadvantages:

• Less commonly used than Tomcat and Jetty.

Advantages and Disadvantages

Enabling HTTP/2 can dramatically improve resource loading times and the overall efficiency of web applications by leveraging multiplexing, header compression, and server push functionalities. However, it also requires more sophisticated server configurations and may involve SSL setup, which adds complexity to the deployment process. Here’s a quick summary:

Advantages:

• Improved Performance: Faster load times by using multiplexed connections.
• Reduced Latency: More efficient use of available network resources.
• Enhanced Efficiency: Header compression and server push reduce redundant client-server communication.

Disadvantages:

• Configuration Complexity: Additional setup for SSL and server configurations.
• Compatibility: Requires modern browsers and server platforms that support HTTP/2.

Similar Topics

Here are some similar questions that users might find helpful:

1. How to configure SSL in Spring Boot?
2. How to enable HTTP/2 cleartext in Spring Boot?
3. How to switch between HTTP/1.1 and HTTP/2 in Spring Boot?
4. How to troubleshoot HTTP/2 issues in Spring Boot?
5. How to integrate Jetty with Spring Boot?
6. How to set up Undertow in a Spring Boot project?
7. How to configure ALPN for HTTP/2 in Spring Boot?
8. How to use server push in HTTP/2 with Spring Boot?
9. How to migrate a Spring Boot application from HTTP/1.1 to HTTP/2?
10. How to use WebFlux with HTTP/2 in Spring Boot?
11. How to enable HTTP compression in Spring Boot?
12. How to manage multiple SSL certificates in Spring Boot?
13. How to handle backward compatibility while enabling HTTP/2?
14. How to monitor HTTP/2 traffic in a Spring Boot application?
15. How to configure a Maven build to support HTTP/2 in Spring Boot?
16. How to add custom headers in HTTP/2 responses in Spring Boot?

By following this guide, you will be able to enable HTTP/2 in your Spring Boot application, ensuring better performance, reduced latency, and enhanced efficiency for your web applications.