Add new library publishing with docs

Author: jiangzho

docs/spark_operator_api_library.md

@@ -0,0 +1,51 @@
+<!--
+Licensed to the Apache Software Foundation (ASF) under one
+or more contributor license agreements.  See the NOTICE file
+distributed with this work for additional information
+regarding copyright ownership.  The ASF licenses this file
+to you under the Apache License, Version 2.0 (the
+"License"); you may not use this file except in compliance
+with the License.  You may obtain a copy of the License at
+
+  http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing,
+software distributed under the License is distributed on an
+"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+KIND, either express or implied.  See the License for the
+specific language governing permissions and limitations
+under the License.
+-->
+
+# Use Spark Operator API Library in Your Java Application
+
+In addition to direct YAML, you may also leverage our Java API library to create and manage Spark
+workloads.
+
+## Choosing the Right Dependency
+
+We publish two variants of this library:
+
+```groovy
+implementation("org.apache.spark:spark-operator-api")
+```
+
+This library keeps your project free from a direct dependency on Fabric8 Kubernetes Client. It's
+recommended if you only interact with our API at the YAML/CRD level (e.g. generating manifests,
+using our higher-level abstractions). Use this if you don’t need direct access to Fabric8 model
+objects like PodTemplateSpec, Deployment, etc.
+
+If your application requires access on fabric8 models, it's recommended to use
+
+```groovy
+implementation("org.apache.spark:spark-operator-api-fabric8")
+```
+
+This library publishes the same core library, with Fabric8 declared as an API dependency. This
+means Fabric8 model classes (Pod, PodTemplateSpec, Deployment, etc.) are available directly on
+your classpath when you depend on our library. It's recommended if you want to compose or extend
+Spark Operator API using Fabric8 types (for example, embedding a Fabric8 PodTemplateSpec into
+Spark Operator CRD).
+
+Do not depend on both `spark-operator-api` and `spark-operator-api-fabric8` at the same time. They
+contain the same classes and will conflict on the classpath. Choose one based on your use case.

settings.gradle

@@ -18,6 +18,7 @@
  */
 rootProject.name = 'apache-spark-kubernetes-operator'
 include 'spark-operator-api'
+include 'spark-operator-api-fabric8'
 include 'spark-submission-worker'
 include 'spark-operator'
 include "build-tools-docs-utils"

spark-operator-api-fabric8/build.gradle

@@ -0,0 +1,30 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+plugins {
+    id 'java-library'
+}
+
+dependencies {
+    api project(":spark-operator-api")
+    // fabric8
+    api(libs.kubernetes.client) {
+        exclude group: 'com.squareup.okhttp3'
+    }
+}

spark-operator-api/build.gradle

@@ -22,7 +22,7 @@ plugins {
 
 dependencies {
   // fabric8
-  api(libs.kubernetes.client) {
+  implementation(libs.kubernetes.client) {
     exclude group: 'com.squareup.okhttp3'
   }
   compileOnly(libs.crd.generator.apt)