Create a Piranha Embedded GraalVM application

Can you create a GraalVM application with Piranha Embedded?

In 6 steps you will learn how to so. They are:

Create the Maven POM file
Add the application class
Add the servlet class
Add the module-info
Build the GraalVM binary
Run the GraalVM binary

Create the Maven POM file

Create an empty directory to store your Maven project. Inside of that directory create the pom.xml file with the content as below.

<?xml version="1.0" encoding="UTF-8"?>

<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0
                             http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>cloud.piranha.guides.embedded</groupId>
    <artifactId>graalvm</artifactId>
    <version>1-SNAPSHOT</version>
    <packaging>jar</packaging>
    <name>Piranha Embedded - Create a GraalVM application</name>
    <properties>
        <exec-maven-plugin.version>3.1.0</exec-maven-plugin.version>
        <java.version>17</java.version>
        <maven-compiler-plugin.version>3.11.0</maven-compiler-plugin.version>
        <maven-jar-plugin.version>3.3.0</maven-jar-plugin.version>
        <piranha.version>23.6.0</piranha.version>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>
    <build>
        <finalName>helloworld</finalName>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>${maven-compiler-plugin.version}</version>
                <configuration>
                    <release>${java.version}</release>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.codehaus.mojo</groupId>
                <artifactId>exec-maven-plugin</artifactId>
                <version>${exec-maven-plugin.version}</version>
                <configuration>
                    <mainClass>helloworld.HelloWorld</mainClass>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-jar-plugin</artifactId>
                <version>${maven-jar-plugin.version}</version>
                <configuration>
                    <archive>
                        <manifest>
                            <mainClass>helloworld.HelloWorld</mainClass>
                        </manifest>
                    </archive>
                </configuration>
            </plugin> 
        </plugins>
    </build>
    <dependencies>
        <dependency>
            <groupId>cloud.piranha</groupId>
            <artifactId>piranha-embedded</artifactId>
            <version>${piranha.version}</version>
            <scope>compile</scope>
        </dependency>
        <dependency>
            <groupId>cloud.piranha.http</groupId>
            <artifactId>piranha-http-impl</artifactId>
            <version>${piranha.version}</version>
            <scope>compile</scope>
        </dependency>
        <dependency>
            <groupId>cloud.piranha.http</groupId>
            <artifactId>piranha-http-webapp</artifactId>
            <version>${piranha.version}</version>
            <scope>compile</scope>
        </dependency>
    </dependencies>
    <profiles>
        <profile>
            <id>graalvm</id>
            <build>
                <plugins>
                    <plugin>
                        <groupId>org.graalvm.nativeimage</groupId>
                        <artifactId>native-image-maven-plugin</artifactId>
                        <version>21.2.0</version>
                        <executions>
                            <execution>
                                <goals>
                                    <goal>native-image</goal>
                                </goals>
                                <phase>package</phase>
                            </execution>
                        </executions>
                        <configuration>
                            <skip>false</skip>
                            <imageName>helloworld</imageName>
                            <buildArgs>-H:Log=registerResource:5 -H:IncludeResourceBundles=jakarta.servlet.LocalStrings -H:IncludeResourceBundles=jakarta.servlet.http.LocalStrings --no-fallback --install-exit-handlers</buildArgs>
                        </configuration>
                    </plugin>                    
                </plugins>
            </build>
        </profile>
    </profiles>
</project>

Add the application class

Add the HelloWorldApplication class in the src/main/java directory, which allows you to configure the EmbeddedPiranha instance as well as the DefaultHttpServer instance.

package helloworld;

import cloud.piranha.embedded.EmbeddedPiranha;
import cloud.piranha.embedded.EmbeddedPiranhaBuilder;
import cloud.piranha.http.impl.DefaultHttpServer;
import cloud.piranha.http.webapp.HttpWebApplicationServerProcessor;

public class HelloWorldApplication {

    public static void main(String[] arguments) throws Exception {
        EmbeddedPiranha piranha = new EmbeddedPiranhaBuilder()
                .servlet("HelloWorld", HelloWorldServlet.class)
                .servletMapping("HelloWorld", "/*")
                .buildAndStart();
        
        DefaultHttpServer server = new DefaultHttpServer(8080, 
                new HttpWebApplicationServerProcessor(piranha), false);
        
        server.start();
    }
}

Add the servlet

And we are adding a simple HelloWorld servlet.

package helloworld;

import java.io.IOException;
import java.io.PrintWriter;
import jakarta.servlet.ServletException;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;

public class HelloWorldServlet extends HttpServlet {
    
    /**
     * Constructor.
     * 
     * <p>
     *  Note the constructor is needed here to make it so we can generate the
     *  GraalVM binary. See META-INF/native-image for more information.
     * </p>
     */
    public HelloWorldServlet() {
    }
    
    @Override
    protected void doGet(HttpServletRequest request, 
            HttpServletResponse response) throws IOException, ServletException {
        try (PrintWriter writer = response.getWriter()) {
            writer.println("Hello World!");
            writer.flush();
        }
    }
}

Add the module info

Now add the module-info.java to the src/main/java directory.

module helloworld {

    exports helloworld;
    requires cloud.piranha.http.api;
    requires cloud.piranha.http.impl;
    requires cloud.piranha.http.webapp;
    requires jakarta.servlet;
}

Build the application

The following command line will build your application:

  mvn verify

Build the GraalVM binary

The following command line will use Docker to build the GraalVM binary:

  docker build -t graalvm -f Dockerfile .

Execute the GraalVM binary

The following command will use the generated Docker image to execute your GraalVM binary.

  docker run --rm -it -p 8080:8080 graalvm

Conclusion

As you can see creating a GraalVM application with Piranha Embedded is a few easy steps away!

References

Piranha Embedded