Spring Boot with GraalVM

Known GraalVM Native Image limitations

General

• Signed JARs are not supported, see spring-framework#29019

Testing

• Mockito is not supported yet, see #32195. You can disable tests which rely on Mockito with @DisabledInNativeImage.

Building Container Images

• Buildpacks do not yet have official support for building images for ARM. Instructions for creating your own ARM-compatible builder are available.

WebJars

• WebJars are not recommended with native images since the webjars-locator-core dependency involves unsupported resource scanning at runtime, and since WebJars dependencies lead to the inclusion of unneeded resources from META-INF/resources/. Alternative approaches like directly shipping the required frontend resources in the web application, potentially by leveraging Node.js Gradle or Maven integration if needed, should be preferred.

Further GraalVM tweaking

Using tomcat-embed-programmatic

Motivation

tomcat-embed-programmatic is an experimental Tomcat dependency designed to lower the memory footprint. Using it produces smaller native images.

Maven

<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-web</artifactId>
  <exclusions>
    <exclusion>
      <groupId>org.apache.tomcat.embed</groupId>
      <artifactId>tomcat-embed-core</artifactId>
    </exclusion>
    <exclusion>
      <groupId>org.apache.tomcat.embed</groupId>
      <artifactId>tomcat-embed-websocket</artifactId>
    </exclusion>
  </exclusions>
</dependency>
<dependency>
  <groupId>org.apache.tomcat.experimental</groupId>
  <artifactId>tomcat-embed-programmatic</artifactId>
  <version>${tomcat.version}</version>
</dependency>

Gradle

implementation('org.springframework.boot:spring-boot-starter-web') {
  exclude group: 'org.apache.tomcat.embed', module: 'tomcat-embed-core'
  exclude group: 'org.apache.tomcat.embed', module: 'tomcat-embed-websocket'
}
String tomcatVersion = dependencyManagement.importedProperties['tomcat.version']
implementation "org.apache.tomcat.experimental:tomcat-embed-programmatic:$tomcatVersion"