Blaze by Fizzed

Overview

A speedy, flexible, general purpose scripting and application launching stack for the JVM. Can replace shell scripts and plays nicely with other tools. Only requires a Java 8 runtime and adding blaze.jar to your project directory. Start writing portable and cross-platform scripts.

Blaze pulls together stable, mature libraries from the Java ecosystem into a light-weight package that lets you focus on getting things done. When you invoke blaze, it does the following:

• Sets up console logging
• Loads your optional configuration file(s)
• Downloads runtime dependencies (e.g. jars from Maven central)
• Loads and compiles your script(s)
• Executes "tasks" (methods your script defines)

Includes the following features:

• Write your applications (scripts) in whatever JVM language you prefer. Out-of-the-box support for
  • Java (.java) (8, 11, 17, 21, etc.)
  • Groovy (.groovy) (v4.0.15)
  • Kotlin (.kt) (v1.9.10)
  • JavaScript (.js) (via nashorn on Java 11+)
  • Or write your own (examples here, here, and here)
• Zero-install required. Just drop blaze.jar into your project directory and you or others can run it with java -jar blaze.jar.
• IDE support
• Small size so you can commit blaze.jar to your repository
• Excellent framework support for executing processes, modifying the filesystem, user interaction, http, and ssh.
• Easily use any Java library as a dependency to accomplish whatever the framework doesn't provide.

Sponsorship & Support

Project by Fizzed, Inc. (Follow on Twitter: @fizzed_inc)

Developing and maintaining opensource projects requires significant time. If you find this project useful or need commercial support, we'd love to chat. Drop us an email at [email protected]

Project sponsors may include the following benefits:

• Priority support (outside of Github)
• Feature development & roadmap
• Priority bug fixes
• Privately hosted continuous integration tests for their unique edge or use cases

What is a blaze script?

A Blaze script is a 100% valid JVM class with public methods that typically uses an empty (root) package declaration. Each public method becomes the externally accessible task that can be called from the command-line. Since most JVM languages support this kind of structure, Blaze can easily support a wide variety of JVM languages.

More documentation

• Why Blaze?
• Examples
• Configuration and dependency management
• Basic usage
• SSH plugin
• HTTP plugin

Try It

To give this project a quick try on your own machine, just run some of the examples:

git clone https://github.com/fizzed/blaze.git
cd blaze
java -jar blaze.jar examples/hello.java
java -jar blaze.jar examples/natives.java
java -jar blaze.jar examples/find_javas.java

Install to your project

Download blaze.jar to your project directory. If you have wget available

wget -O blaze.jar 'https://repo1.maven.org/maven2/com/fizzed/blaze-lite/1.6.1/blaze-lite-1.6.1.jar'

If you have curl available

curl -o blaze.jar 'https://repo1.maven.org/maven2/com/fizzed/blaze-lite/1.6.1/blaze-lite-1.6.1.jar'

Or simply download the file in your web browser and save it to your project directory with a name of blaze.jar

Write hello world blaze script in .java

Create blaze.java file

public class blaze {
    
    public void main() {
        System.out.println("Hello World!");
    }
    
}

Run blaze script

Since you named your file blaze.java, Blaze will find it automatically. You can run it like so

java -jar blaze.jar

If no task is supplied on the command line, Blaze will attempt to run the main task by default.

Write script that executes a process

Let's do a more useful example of how we use Blaze in many cases. Let's say you had a Maven project and wanted to execute a class with a main method. The syntax to do that in Maven becomes difficult to remember and communicate to other developers. Blaze lets you simplify the entry points to your project by exposing everything as named tasks.

import static com.fizzed.blaze.Systems.exec;

public class blaze {

    public void demo1() {
        exec(
           "mvn", "compile", "exec:java", "-Dexec.classpathScope=runtime",
           "-Dexec.mainClass=com.example.Demo1").run();
    }

    public void demo2() {
        exec(
           "mvn", "compile", "exec:java", "-Dexec.classpathScope=runtime",
           "-Dexec.mainClass=com.example.Demo2").run();
    }
}

You can now just run these with java -jar blaze.jar demo1 or java -jar blaze.jar demo2

Avoid "Terminate batch job (Y/N)" on CTRL+C in Windows

If you leverage powershell on Windows, Blaze v1.6.0+ will install a blaze.ps1 via the "-i" installer flag. This powershell script will help you avoid the infuriating "Terminate batch job (Y/N)" prompt on Windows.

Avoid zombie processes triggered with maven and CTRL+C on Windows

On windows if you run maven, and it in turn creates child processes for javadocs, exec plugin, etc., in almost all cases, maven will close but leave the processes it opened still running. The problem is that Windows itself does not close the process hierarchy if the parent is terminated, like Linux or MacOS will do.

As of Blaze v1.6.0+, any blaze exec() action will automatically destroy any running processes as well as any child processes upon shutdown via CTRL+C (or any reason for an exit). Blaze makes Maven on Windows much easier to use.

But I can still do your previous example in a shell script?

Yeah, I suppose so. But you'd probably use two shell scripts to define the separate tasks and if you cared about platform portability, you'd be nice to also include .bat scripts for Windows users. However, when you want to do anything else that's remotely advanced, you'll start to appreciate having a more advanced environment.

An example of finding a specific JDK on your local system to execute a Maven test with it.

find_java.conf

blaze.dependencies = [
  "com.fizzed:jne:4.1.1"
]

find_java.java

public class blaze {

   private final Logger log = Contexts.logger();
   private final Config config = Contexts.config();
   private final Path projectDir = withBaseDir("..").toAbsolutePath();
    
   @Task
   public void test() throws Exception {
      // optional command-line arguments to control which jdk version or hardware architecture
      final Integer jdkVersion = this.config.value("jdk.version", Integer.class).orNull();
      final HardwareArchitecture jdkArch = ofNullable(this.config.value("jdk.arch").orNull())
              .map(HardwareArchitecture::resolve)
              .orElse(null);

      final long start = System.currentTimeMillis();
      final JavaHome jdkHome = new JavaHomeFinder()
              .jdk()
              .version(jdkVersion)
              .hardwareArchitecture(jdkArch)
              .preferredDistributions()
              .sorted(jdkVersion != null || jdkArch != null)  // sort if any criteria provided
              .find();

      log.info("");
      log.info("Detected {} (in {} ms)", jdkHome, (System.currentTimeMillis()-start));
      log.info("");

      exec("mvn", "clean", "test")
              .workingDir(projectDir)
              .env("JAVA_HOME", jdkHome.getDirectory().toString())
              .verbose()
              .run();
   }
    
}

Another example where we query git for the latest tag and use it to update a README file with it. We use this as a way to maintain a README file with the latest version pushed to Maven central

import com.fizzed.blaze.Contexts;
import static com.fizzed.blaze.Contexts.withBaseDir;
import static com.fizzed.blaze.Contexts.fail;
import static com.fizzed.blaze.Systems.exec;
import com.fizzed.blaze.core.Actions;
import com.fizzed.blaze.core.Blaze;
import com.fizzed.blaze.util.Streamables;
import java.io.BufferedWriter;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.StandardCopyOption;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import org.slf4j.Logger;

public class blaze {
    static private final Logger log = Contexts.logger();
    
    private String latest_tag() {
        // get latest tag from git
        return exec("git", "describe", "--abbrev=0", "--tags")
            .runCaptureOutput()
            .toString()
            .trim();
    }
    
    public void update_readme() throws IOException {
        Path readmeFile = withBaseDir("../README.md");
        Path newReadmeFile = withBaseDir("../README.md.new");
        
        // find latest version via git tag, trim off leading 'v'
        String taggedVersion = latest_tag().substring(1);
        
        log.info("Tagged version: {}", taggedVersion);
        
        // find current version in readme using a regex to match
        // then apply a mapping function to return the first group of each match
        // then we only need to get the first matched group
        String versionRegex = ".*lite-(\\d+\\.\\d+\\.\\d+)\\.jar.*";
        String readmeVersion
            = Streamables.matchedLines(input(readmeFile), versionRegex, (m) -> m.group(1))
                .findFirst()
                .get();
        
        log.info("Readme version: {}", readmeVersion);
        
        if (readmeVersion.equals(taggedVersion)) {
            log.info("Versions match (no need to update README)");
            return;
        }
        
        // replace version in file and write a new version
        final Pattern replacePattern = Pattern.compile(readmeVersion);
        try (BufferedWriter writer = Files.newBufferedWriter(newReadmeFile)) {
            Files.lines(readmeFile)
                .forEach((l) -> {
                    Matcher matcher = replacePattern.matcher(l);
                    String newLine = matcher.replaceAll(taggedVersion);
                    try {
                        writer.append(newLine);
                        writer.append("\n");
                    } catch (IOException e) {
                        throw new UncheckedIOException(e);
                    }
                });
            writer.flush();
        }
        
        // replace readme with updated version
        Files.move(newReadmeFile, readmeFile, StandardCopyOption.REPLACE_EXISTING);
    }
}

Optionally install blaze on your PATH

While you can invoke blaze.jar as an executable jar by running

java -jar blaze.jar

Sometimes it's more convenient to have a system-wide executable installed on your PATH to make that even shorter. Blaze has a built-in method to copy a wrapper script to a directory. On Linux or Mac OSX, you can run the following

sudo java -jar blaze.jar -i /usr/local/bin

On Windows, open up a shell as an administrator (Start Menu -> Command Prompt > right mouse click Run as administrator), then run the following

java -jar blaze.jar -i C:\Windows\System32

Depending on your operating system, this will install either a blaze shell script or a blaze.bat batch script. Assuming /usr/local/bin or C:\Windows\System32 is already on your PATH (which normally it is), then you can now just run the following in your shell

blaze

IDE support

Writing your blaze scripts in an IDE is significantly more productive than trying to write them in a text editor. We initially tried writing our own IDE plugins to automatically recognize blaze was present, but that proved too difficult to maintain over IDE versions. As of Blaze v1.6.1+, there is a new simple method to enable IDE support across any IDE that supports Maven projects.

java -jar blaze.jar --generate-maven-project

This command will leverage the location of the script currently being executed, calculate the dependencies it needs to run, and then create a minimal pom.xml in the same directory. You can then open that pom.xml in any IDE, and you'll get all the full blown features of your IDE to efficiently write and maintain your blaze scripts.

The --generate-maven-project command will set the target source version to Java 8 by default. If you need to override this to something else, you can add a [blaze-script].conf file that is associated with your blaze script, and add the following configuration values:

java.source.version = 11

You can also pass this is on the command line:

blaze --generate-maven-project -Djava.source.version=17

Where to save your script(s)

Blaze is designed to play nicely with other popular JVM build tools such as Maven, Gradle, Ant, SBT, etc. Blaze is also designed to play nicely with your favorite IDE. If you are planning on a blaze-only project, then create a blaze.[ext] file in your project directory (at the same level as your blaze.jar). Your project directory would be

<project directory>/
    blaze.jar
    blaze.[ext]

The [ext] would be whatever JVM language you'd like to write your script in. So java would be .java, groovy would be .groovy, etc.

However, if you are using another build tool such as Maven, we'd suggest creating a sub-directory called .blaze or blaze and placing your blaze.[ext] script in there. Most Java IDEs compute classpaths for auto completion based on directory paths and placing your script in the root directory doesn't work very well with IDEs like Netbeans. So a maven project + blaze would be

<project directory>/
    .blaze/
        blaze.[ext]
    blaze.jar
    pom.xml

In either setup, you'd run your script identically. That's because blaze will first search the current directory for blaze.[ext] then .blaze/blaze.[ext] then blaze/blaze.[ext]

If you'd like to have more than one script, you can supply it on the command-line like so

java -jar blaze.jar path/to/script.[ext]