FROM maven:3.6.2-jdk-11-slim as builder

WORKDIR /app

COPY pom.xml .

COPY src ./src

RUN mvn compile assembly:single

FROM adoptopenjdk/openjdk11:alpine

RUN apk --no-cache add graphviz ttf-ubuntu-font-family

COPY --from=builder /app/target/system-package-*.jar /system-package.jar

CMD ["java","-jar","/system-package.jar"]

This sample shows how to use a CLI tool installed as a system package as part of a web service.

Use it with the [Using system packages tutorial](https://cloud.google.com/run/docs/tutorials/system-packages).

For more details on how to work with this sample read the [Google Cloud Run Java Samples README](https://github.com/GoogleCloudPlatform/java-docs-samples/run).

* **Spark**: Web server framework.

* **Junit**: [development] Test running framework.

<?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>com.example.cloudrun</groupId>

<artifactId>system-package</artifactId>

<version>1.0-SNAPSHOT</version>

<!--

<parent>

<groupId>com.google.cloud.samples</groupId>

<artifactId>shared-configuration</artifactId>

<version>1.0.11</version>

</parent>

<properties>

<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>

<maven.compiler.source>11</maven.compiler.source>

<maven.compiler.target>11</maven.compiler.target>

</properties>

<dependencies>

<dependency>

<groupId>com.sparkjava</groupId>

<artifactId>spark-core</artifactId>

<version>2.8.0</version>

</dependency>

<dependency>

<groupId>org.slf4j</groupId>

<artifactId>slf4j-simple</artifactId>

<version>1.7.26</version>

</dependency>

<dependency>

<groupId>junit</groupId>

<artifactId>junit</artifactId>

<version>4.11</version>

<scope>test</scope>

</dependency>

</dependencies>

<build>

<plugins>

<plugin>

<groupId>org.apache.maven.plugins</groupId>

<artifactId>maven-surefire-plugin</artifactId>

<version>2.18.1</version>

<configuration>

<redirectTestOutputToFile>true</redirectTestOutputToFile>

</configuration>

</plugin>

<plugin>

<artifactId>maven-compiler-plugin</artifactId>

<version>3.8.0</version>

</plugin>

<plugin>

<artifactId>maven-assembly-plugin</artifactId>

<configuration>

<archive>

<manifest>

<mainClass>com.example.cloudrun.App</mainClass>

</manifest>

</archive>

<descriptorRefs>

<descriptorRef>jar-with-dependencies</descriptorRef>

</descriptorRefs>

</configuration>

</plugin>

</plugins>

</build>

</project>

package com.example.cloudrun;

import static spark.Spark.get;

import static spark.Spark.port;

import java.io.InputStream;

import java.io.OutputStream;

import java.io.OutputStreamWriter;

import java.io.Writer;

import java.util.ArrayList;

import java.util.List;

public class App {

public static void main(String[] args) {

int port = Integer.parseInt(System.getenv().getOrDefault("PORT", "8080"));

port(port);

// [START run_system_package_handler]

get(

"/diagram.png",

(req, res) -> {

InputStream image = null;

try {

String dot = req.queryParams("dot");

image = createDiagram(dot);

res.header("Content-Type", "image/png");

res.header("Content-Length", Integer.toString(image.available()));

res.header("Cache-Control", "public, max-age=86400");

} catch (Exception e) {

if (e.getMessage().contains("syntax")) {

res.status(400);

return String.format("Bad Request: %s", e.getMessage());

} else {

res.status(500);

return "Internal Server Error";

}

}

return image;

});

// [END run_system_package_handler]

}

// [START run_system_package_exec]

// Generate a diagram based on a graphviz DOT diagram description.

public static InputStream createDiagram(String dot) {

if (dot == null || dot.isEmpty()) {

throw new NullPointerException("syntax: no graphviz definition provided");

}

// Adds a watermark to the dot graphic.

List<String> args = new ArrayList<String>();

args.add("/usr/bin/dot");

args.add("-Glabel=\"Made on Cloud Run\"");

args.add("-Gfontsize=10");

args.add("-Glabeljust=right");

args.add("-Glabelloc=bottom");

args.add("-Gfontcolor=gray");

args.add("-Tpng");

StringBuilder output = new StringBuilder();

InputStream stdout = null;

try {

ProcessBuilder pb = new ProcessBuilder(args);

Process process = pb.start();

OutputStream stdin = process.getOutputStream();

stdout = process.getInputStream();

// The Graphviz dot program reads from stdin.

Writer writer = new OutputStreamWriter(stdin, "UTF-8");

writer.write(dot);

writer.close();

process.waitFor();

} catch (Exception e) {

System.out.println(e);

}

return stdout;

}

// [END run_system_package_exec]

}

package com.example.cloudrun;

import static org.junit.Assert.assertEquals;

import static org.junit.Assert.assertTrue;

import static spark.Spark.awaitInitialization;

import static spark.Spark.stop;

import java.io.IOException;

import java.net.HttpURLConnection;

import java.net.URL;

import org.junit.AfterClass;

import org.junit.BeforeClass;

import org.junit.Test;

import spark.utils.IOUtils;

public class AppTest {

private static String BASE_URL = "/diagram.png";

private static String DOT = "?dot=";

@BeforeClass

public static void beforeClass() {

App app = new App();

app.main(new String[] {});

awaitInitialization();

}

@AfterClass

public static void afterClass() {

stop();

}

@Test

public void shouldFailWithNoQuery() {

try {

TestResponse response = executeRequest("GET", BASE_URL);

assertEquals(true, response);

} catch (IOException e) {

assertTrue(e.getMessage().startsWith("Server returned HTTP response code: 400 for URL"));

}

}

@Test

public void shouldFailWithEmptyDotParam() {

try {

executeRequest("GET", BASE_URL + DOT);

} catch (IOException e) {

assertTrue(e.getMessage().startsWith("Server returned HTTP response code: 400 for URL"));

}

}

@Test

public void shouldFailWithInvalidPayload() {

try {

executeRequest("GET", BASE_URL + DOT + "digraph");

} catch (IOException e) {

assertTrue(e.getMessage().startsWith("Server returned HTTP response code: 400 for URL"));

}

}

@Test

public void shouldSucceed() throws IOException {

String query = "digraph%20G%20{%20A%20->%20{B,%20C,%20D}%20->%20{F}%20}";

TestResponse response = executeRequest("GET", BASE_URL + DOT + query);

assertEquals(200, response.status);

}

private static TestResponse executeRequest(String method, String path) throws IOException {

URL url = new URL("http://localhost:8080" + path);

HttpURLConnection connection = (HttpURLConnection) url.openConnection();

connection.setRequestMethod(method);

connection.setDoOutput(true);

connection.connect();

String body = IOUtils.toString(connection.getInputStream());

return new TestResponse(connection.getResponseCode(), body);

}

public static class TestResponse {

public final String body;

public final int status;

public TestResponse(int status, String body) {

this.status = status;

this.body = body;

}

}

}