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Production Build

How to create a production-ready package of an application, which can then be deployed.

If you generated your application with Hilla CLI, you can create a production build by running the following command on the command-line:

mvn clean package -Pproduction

Executing this line builds a JAR file, with all of the dependencies and bundled front-end resources, ready to be deployed. You can find the file in the target folder after the build is finished.

Enabling Production Builds

The production build command works out-of-the-box for Hilla starter projects. For example, it works with projects that are generated using the Hilla CLI. The starter projects come with the necessary Maven configuration. If you’ve manually created your project’s pom.xml file, add the following Maven profile to enable production builds:

<profile>
    <!-- Production mode is activated using -Pproduction -->
    <id>production</id>
    <build>
        <plugins>
            <plugin>
                <groupId>dev.hilla</groupId>
                <artifactId>hilla-maven-plugin</artifactId>
                <version>${hilla.version}</version>
                <executions>
                    <execution>
                        <goals>
                            <goal>build-frontend</goal>
                        </goals>
                        <phase>compile</phase>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</profile>

The actual content of the profile depends on the environment in which your application is running. However, all of the variants call the Maven goal hilla:build-frontend.

Creating a Production Build

To create a production build, you can execute mvn clean package -Pproduction. This builds a JAR or WAR file with all of the dependencies and front-end resources compiled and ready to be deployed. The file is created in the target folder after the build completes.

If you don’t have the production Maven profile in your POM file, the easiest way to get it is to create a project base using the CLI. Then copy the production profile from the downloaded POM file.

Having a production build as a separate Maven profile should help to avoid any unexpected problems during development, due to production settings.

Note
Building for 64-Bit
If your operating system is 64-bit, be sure to use a 64-bit JDK installation, as well.

Excluding Development Server Module

The Vite server integration and live-reload features — which are available only during development — are contained in the module com.vaadin:vaadin-dev-server. You should exclude this module from production builds. You can do so by adding the following dependency exclusion to the <dependencies> section in the production profile:

<profiles>
    <profile>
        <id>production</id>

        <!-- above production build configuration -->

        <dependencies>
            <dependency>
                <groupId>com.vaadin</groupId>
                <artifactId>vaadin-core</artifactId>
                <exclusions>
                    <exclusion>
                        <groupId>com.vaadin</groupId>
                        <artifactId>vaadin-dev</artifactId>
                    </exclusion>
                </exclusions>
            </dependency>
        </dependencies>
    </profile>
</profiles>

This results in less code and fewer dependency libraries being bundled in the production application.

Transpilation & Bundling

Transpilation in Hilla means converting all ES6 JavaScript to ES5 JavaScript format for older browsers. All Vaadin components are written using ES6, and consist of several JavaScript and CSS files. Transpilation ensures the newer JavaScript code also works in browsers that don’t support all of the latest JavaScript features.

During the build, minimization is carried out to make the files smaller. When minifying code, it’s often obfuscated, making it harder to read. Therefore, this isn’t done during development.

Bundling is an optimization in which multiple files are merged into a single collection. This is so that the browser doesn’t need to request so many files from the server. As a result, the application usually loads faster.

Maven Plugin Goals & Goal Parameters

The prepare-frontend Goal

The prepare-frontend goal validates whether the node and npm tools are installed and aren’t too old (i.e., not earlier than version 10 of node, and not earlier than version 5.6 of npm). It also automatically installs them, if they’re missing, in the .vaadin folder, located in the user’s home directory. If they’re installed globally but they’re too old, an error message suggests that you install newer versions. Node.js is needed to run npm to install front-end dependencies and Vite, which bundles the front-end files served to the client.

Additionally, it visits all resources used by the application and copies them to the node_modules folder. This is so that they’re available when Vite builds the frontend. It also creates or updates the package.json, tsconfig.json and vite.generated.json files.

There are a few parameters for this goal. They’re listed here with the default values in parentheses, along with comments or a description of each:

includes (**/*.js,**/*.css)

Comma-separated wildcards for files and directories that should be copied. The default is only .js and .css files.

npmFolder (${project.basedir})

The folder where the package.json file is located. The default is the project root folder.

webpackTemplate (webpack.config.js)

Copy webapp.config.js from the specified URL if it’s missing. The default is the template provided by this plugin. Set it to an empty string to disable the feature.

webpackGeneratedTemplate (webpack.generated.js)

Copy webapp.config.js from the specified URL if it’s missing. The default is the template provided by this plugin. Set it to an empty string to disable the feature.

generatedFolder (${project.build.directory}/frontend/)

The folder where Flow puts generated files that’ll be used by webpack.

require.home.node (false)

If set to true, always prefer Node.js automatically downloaded and installed in the .vaadin directory in the user’s home directory.

The build-frontend Goal

This goal builds the front-end bundle. It’s a complex process involving several steps:

  • Update package.json with all the @NpmPackage annotation values found in the classpath and automatically install these dependencies.

  • Update the JavaScript files containing code to import everything used in the application. These files are generated in the target/frontend folder, and are used as the entry point of the application.

  • Create webpack.config.js, if it’s not found. Otherwise, update it if some project parameters have changed.

  • Generate JavaScript bundles, chunks and transpile to ES5 using the webpack server. The target folder for WAR packaging is target/${artifactId}-${version}/build; for JAR packaging, it’s target/classes/META-INF/resources/build.

There are also a few parameters for this goal. They’re listed here with their default values in parentheses, along with comments or a description of each:

npmFolder (${project.basedir}

The folder where the package.json file is located. The default is the project root folder.

generatedFolder (${project.build.directory}/frontend/)

The folder where Flow puts generated files that’ll be used by webpack.

frontendDirectory (${project.basedir}/frontend)

The directory with the project’s front-end source files.

generateBundle (true)

Whether to generate a bundle from the project front-end sources.

runNpmInstall (true)

Whether to run pnpm install — or npm install, depending on the pnpmEnable parameter value — after updating dependencies.

generateEmbeddableWebComponents (true)

Whether to generate embedded web components from WebComponentExporter inheritors.

optimizeBundle (true)

Whether to include only front-end resources used from application entry points — the default — or to include all resources found on the classpath. It should normally be left to the default, but a value of false can be useful for faster production builds or debugging discrepancies between development and production builds.

pnpmEnable (false)

Whether to use the pnpm or npm tool to handle front-end resources. The default is npm.

useGlobalPnpm (false)

Whether to use a globally installed pnpm tool instead of the default supported version of pnpm.

The clean-frontend Goal

This goal cleans frontend files that may cause inconsistencies when changing versions. Don’t add the goal as a default to pom.xml. Instead, use it with mvn vaadin:clean-frontend when necessary.

Executing the clean-frontend goal removes a few things:

  • the package lock file;

  • the generated frontend folder which is by default, frontend/generated; and

  • the node_modules folder — but this might need manual deletion.

The goal also cleans all dependencies that are managed by the framework, and any dependencies that target the build folder from the package.json file.

The clean-frontend goal supports the same parameters as prepare-frontend.