By default, Spring boot uses Tomcat as embedded Web server. There are, however, other available Web servers in case you need some specific features. In this tutorial we will learn how to use Undertow as Web Server.
Add spring-boot-starter-undertow dependency
You will need to update pom.xml and add dependency for spring-boot-starter-undertow. Also, you will need to exclude default added spring-boot-starter-tomcat dependency as follows:
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
<exclusions>
<exclusion>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-tomcat</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-undertow</artifactId>
</dependency>
If you are using Gradle as build tool, the same result can be achieved using:
configurations {
compile.exclude module: "spring-boot-starter-tomcat"
}
dependencies {
compile("org.springframework.boot:spring-boot-starter-web:2.1.0.RELEASE")
compile("org.springframework.boot:spring-boot-starter-undertow:2.1.0.RELEASE")
}
With this configuration in place, you should be able to switch to Undertow Web Server
Verifying that Spring Boot uses Undertow
When you start your Spring Boot application, look for log entries that mention Undertow. You should see messages similar to the following:
2024-08-22 12:02:57.123 INFO 12345 --- [ main] io.undertow : starting server: Undertow - 2.2.14.Final 2024-08-22 12:02:57.456 INFO 12345 --- [ main] org.xnio : XNIO version 3.8.0.Final 2024-08-22 12:02:57.789 INFO 12345 --- [ main] org.xnio.nio : XNIO NIO Implementation Version 3.8.0.Final 2024-08-22 12:02:58.012 INFO 12345 --- [ main] io.undertow : starting server: Undertow - 2.2.14.Final 2024-08-22 12:02:58.345 INFO 12345 --- [ main] org.springframework.boot.web.embedded.undertow.UndertowWebServer : Undertow started on port(s) 8080 (http)
If the default logs are not sufficient, you can enable more detailed logging for Undertow by adding the following configuration to your application.properties or application.yml:
logging.level.io.undertow=DEBUG logging.level.org.xnio=DEBUG
Finally, if you want to configure Undertow server, check the following article: Configuring Undertow in Spring Boot Applications
Found the article helpful? if so please follow us on Socials
