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java-generation-from-CRD.md

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Java generation from CRD (preview)

This document shows how to generate java sources from CRD manifests.

Quick start CLI

The Java generator CLI is available for download on Sonatype at the link:

https://oss.sonatype.org/content/repositories/releases/io/fabric8/java-generator-cli/<version>/java-generator-cli-<version>.sh

you can get it working locally with few lines:

export VERSION=$(wget -q -O - http://github.com/fabric8io/kubernetes-client/releases/latest --header "Accept: application/json" | jq -r '.tag_name' | cut -c 2-)
wget https://oss.sonatype.org/content/repositories/releases/io/fabric8/java-generator-cli/$VERSION/java-generator-cli-$VERSION.sh
chmod a+x java-generator-cli-$VERSION.sh
./java-generator-cli-$VERSION.sh --version

Alternatively, if you already have jbang installed, you can run the CLI using it:

jbang io.fabric8:java-generator-cli:<version>

Quick start Maven

The Java generator Maven plugin can be used from your project pom.xml adding a section like:

<plugin>
  <groupId>io.fabric8</groupId>
  <artifactId>java-generator-maven-plugin</artifactId>
  <version>${kubernetes-client.version}</version>
  <executions>
    <execution>
      <goals>
        <goal>generate</goal>
      </goals>
    </execution>
  </executions>
  <configuration>
    <source>src/main/resources/kubernetes</source>
    ...
  </configuration>
</plugin>

Usage

Provide a source referencing a file or a folder containing your CRDs definitions in yaml or json format and a target directory where the relevant Java code should be generated.

The full list of options of the CLI is (output of --help):

Usage: java-gen [-hV] [-add-extra-annotations] [-enum-uppercase] -s=<source>
                [-suffix-strategy=<suffixStrategy>] -t=<target>
      -add-extra-annotations, --add-extra-annotations
                          Add extra lombok and sundrio annotation to the
                            generated classes
      -enum-uppercase, --enum-uppercase
                          Uppercase the enum values
  -h, --help              Show this help message and exit.
  -s, --source=<source>   The source(file or folder) with the
                            CustomResourceDefinition(s) to use
      -suffix-strategy, --suffix-strategy=<suffixStrategy>
                          The suffix strategy to be used
  -t, --target=<target>   The folder to write the generated sources
  -V, --version           Print version information and exit.

And the corresponding configurations of the Maven plugin are (output of mvn help:describe -DgroupId=io.fabric8 -DartifactId=java-generator-maven-plugin -Dversion=<version> -Ddetail):

    enumUppercase
      User property: fabric8.java-generator.enum-uppercase

    extraAnnotations
      User property: fabric8.java-generator.extra-annotations

    source
      Required: true
      User property: fabric8.java-generator.source

    suffixStrategy
      User property: fabric8.java-generator.suffix-strategy

    target (Default: ${basedir}/target/generated-sources/java)
      User property: fabric8.java-generator.target

Compiling the generated code

The generated code depends on a few dependencies to succesfully compile:

<dependency>
  <groupId>io.fabric8</groupId>
  <artifactId>kubernetes-client</artifactId>
</dependency>
<dependency>
  <groupId>io.fabric8</groupId>
  <artifactId>generator-annotations</artifactId>
</dependency>

and, if --add-extra-annotations/extraAnnotations has been set, the following dependencies should be included as well:

<dependency> 
  <groupId>io.sundr</groupId> 
  <artifactId>builder-annotations</artifactId> 
  <scope>provided</scope> 
</dependency> 
<dependency> 
  <groupId>org.projectlombok</groupId> 
  <artifactId>lombok</artifactId> 
  <scope>provided</scope> 
</dependency>