Spring Boot§

To run apps based on the Spring Boot frameworks using Unit:

  1. Install Unit with a Java language module.

  2. Create your Spring Boot project; we’ll use the quickstart example, creating it at

    Spring Initializr - Project Setup Screen


    Choose the same Java version that your Unit language module has.

    Download and extract the project files where you need them:

    $ unzip -d /path/to/app/

    This creates a directory named /path/to/app/demo/ for you to add your app code to; in our example, it’s a single file called /path/to/app/demo/src/main/java/com/example/demo/

    package com.example.demo;
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.web.bind.annotation.GetMapping;
    import org.springframework.web.bind.annotation.RequestParam;
    import org.springframework.web.bind.annotation.RestController;
    public class DemoApplication {
      public static void main(String[] args) {, args);
      public String hello(@RequestParam(value = "name", defaultValue = "World") String name) {
        return String.format("Hello, %s!", name);

    Finally, assemble a .war file.

    If you chose Gradle as the build tool:

    $ cd /path/to/app/demo/
    $ ./gradlew bootWar

    If you chose Maven:

    $ cd /path/to/app/demo/
    $ ./mvnw package


    By default, Gradle puts the .war file in the build/libs/ subdirectory, while Maven uses target/; note your path for later use in Unit configuration.

  3. Run the following command so Unit can access the application directory:

    # chown -R unit:unit /path/to/app/


    The unit:unit user-group pair is available only with official packages, Docker images, and some third-party repos. Otherwise, account names may differ; run the ps aux | grep unitd command to be sure.

    For further details, including permissions, see the security checklist.

  4. Next, put together the Spring Boot configuration (use a real value for working_directory):

        "listeners": {
            "*:80": {
                "pass": "applications/bootdemo"
        "applications": {
            "bootdemo": {
                "type": "java",
                "webapp": "gradle-or-maven-build-dir/demo.war",
                "working_directory": "/path/to/app/demo/"
  5. Upload the updated configuration. Assuming the JSON above was added to config.json:

    # curl -X PUT --data-binary @config.json --unix-socket \
           /path/to/control.unit.sock http://localhost/config/


    The control socket path may vary; run unitd -h or see Startup and Shutdown for details.

    After a successful update, your app should be available on the listener’s IP address and port:

    $ curl http://localhost/hello?name=Unit
          Hello, Unit!