add dataflint-spark4-databricks shaded artifact for DBR 17.3+

Databricks Runtime 17.3 ships javax.servlet instead of jakarta.servlet,
crashing the standard Spark 4 plugin at startup with NoClassDefFoundError
on jakarta/servlet/Servlet (issue #47). Add a parallel SBT module
pluginspark4databricks that source-shares with pluginspark4 but applies
ShadeRule.rename("jakarta.servlet.**" -> "javax.servlet.@1") at assembly
time, producing io.dataflint:dataflint-spark4-databricks_2.13. A
Spark4DatabricksPageFactory subclass inverts the Databricks UI gate so
the new jar enables the UI only on DBR (and silently degrades to
listeners-only if accidentally installed on stock Spark 4); the original
Spark4PageFactory is unchanged. Drop the Maven-Central verify step in
cd.yml — it only checked spark_2.12 and didn't work for snapshots.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: minskya

.github/workflows/cd.yml

@@ -95,35 +95,6 @@ jobs:
           SONATYPE_PASSWORD: ${{ secrets.SONATYPE_PASSWORD }}
           SONATYPE_USERNAME: ${{ secrets.SONATYPE_USERNAME }}
 
-      - name: Verify artifact published
-        run: |
-          VERSION=$(grep 'lazy val versionNum' build.sbt | grep -oE '"[0-9.]+"' | tr -d '"')
-          if [[ "$IS_RELEASE" == "true" ]]; then
-            URL="https://repo1.maven.org/maven2/io/dataflint/spark_2.12/${VERSION}/spark_2.12-${VERSION}.pom"
-            AUTH_ARGS=""
-            EXPECTED_VERSION="${VERSION}"
-          else
-            URL="https://central.sonatype.com/repository/maven-snapshots/io/dataflint/spark_2.12/maven-metadata.xml"
-            AUTH_ARGS="-u ${SONATYPE_USERNAME}:${SONATYPE_PASSWORD}"
-            EXPECTED_VERSION="${VERSION}-SNAPSHOT"
-          fi
-          echo "Verifying $EXPECTED_VERSION at: $URL"
-          sleep 15
-          for i in $(seq 1 10); do
-            if curl -sf $AUTH_ARGS "$URL" | grep -q "${EXPECTED_VERSION}"; then
-              echo "Artifact published successfully"
-              exit 0
-            fi
-            echo "Attempt $i/10 — waiting 30s..."
-            sleep 30
-          done
-          echo "Artifact not found after 5 minutes"
-          exit 1
-        working-directory: ./spark-plugin
-        env:
-          SONATYPE_USERNAME: ${{ secrets.SONATYPE_USERNAME }}
-          SONATYPE_PASSWORD: ${{ secrets.SONATYPE_PASSWORD }}
-
       - name: Create Release
         if: github.event.inputs.release_type == 'official' || startsWith(github.ref, 'refs/tags/v')
         run: |

README.md

@@ -125,7 +125,7 @@ spark-submit
 * There is also support for scala 2.13, if your spark cluster is using scala 2.13 change package name to io.dataflint:spark_**2.13**:0.9.6
 * For more installation options, including for **python** and **k8s spark-operator**, see [Install on Spark docs](https://dataflint.gitbook.io/dataflint-for-spark/getting-started/install-on-spark)
 * For installing DataFlint OSS in **spark history server** for observability on completed runs see [install on spark history server docs](https://dataflint.gitbook.io/dataflint-for-spark/getting-started/install-on-spark-history-server)
-* For installing DataFlint OSS on **DataBricks** see [install on databricks docs](https://dataflint.gitbook.io/dataflint-for-spark/getting-started/install-on-databricks)
+* For installing DataFlint OSS on **DataBricks** see [install on databricks docs](https://dataflint.gitbook.io/dataflint-for-spark/getting-started/install-on-databricks). Databricks Runtime 17.3+ ships `javax.servlet` instead of `jakarta.servlet`, so use the dedicated shaded artifact `io.dataflint:dataflint-spark4-databricks_2.13` (same plugin class — only the jar coordinate differs).
 
 ## How it Works
 

spark-plugin/build.sbt

@@ -12,6 +12,7 @@ lazy val dataflint = project
     plugin,
     pluginspark3,
     pluginspark4,
+    pluginspark4databricks,
     example_3_1_3,
     example_3_2_4,
     example_3_3_3,
@@ -162,11 +163,66 @@ lazy val pluginspark4 = (project in file("pluginspark4"))
 
     // Include source from plugin directory for self-contained build
     Compile / unmanagedSourceDirectories += (plugin / Compile / sourceDirectory).value / "scala",
-    
+
     // Include resources from plugin directory for static UI files
     Compile / unmanagedResourceDirectories += (plugin / Compile / resourceDirectory).value
   )
 
+lazy val pluginspark4databricks = (project in file("pluginspark4databricks"))
+  .enablePlugins(AssemblyPlugin)
+  .settings(
+    name := "dataflint-spark4-databricks",
+    organization := "io.dataflint",
+    scalaVersion := scala213,
+    crossScalaVersions := List(scala213), // Only Scala 2.13 for Spark 4.x
+    version      := (if (git.gitCurrentTags.value.exists(_.startsWith("v"))) {
+      versionNum
+    } else {
+      versionNum + "-SNAPSHOT"
+    }),
+    libraryDependencies += "org.apache.spark" %% "spark-core" % "4.0.1" % "provided",
+    libraryDependencies += "org.apache.spark" %% "spark-sql" % "4.0.1"  % "provided",
+    libraryDependencies +=  "com.amazonaws" % "aws-java-sdk-s3" % "1.12.470" % "provided",
+    libraryDependencies += "org.apache.iceberg" %% "iceberg-spark-runtime-3.5" % "1.5.0" % "provided",
+    libraryDependencies += "io.delta" %% "delta-spark" % "3.2.0" % "provided",
+
+    // Source-share with pluginspark4 + plugin so we don't duplicate code.
+    Compile / unmanagedSourceDirectories += (pluginspark4 / Compile / sourceDirectory).value / "scala",
+    Compile / unmanagedSourceDirectories += (plugin / Compile / sourceDirectory).value / "scala",
+    Compile / unmanagedResourceDirectories += (plugin / Compile / resourceDirectory).value,
+
+    // Drop the upstream DataflintSparkUILoader so our local copy (which uses
+    // Spark4DatabricksPageFactory) is the one compiled.
+    Compile / unmanagedSources / excludeFilter := {
+      val upstreamLoader = (pluginspark4 / Compile / sourceDirectory).value /
+        "scala" / "org" / "apache" / "spark" / "dataflint" / "DataflintSparkUILoader.scala"
+      new sbt.io.SimpleFileFilter(_.getCanonicalPath == upstreamLoader.getCanonicalPath)
+    },
+
+    assembly / assemblyJarName := s"${name.value}_${scalaBinaryVersion.value}-${version.value}.jar",
+    assembly / assemblyOption := (assembly / assemblyOption).value.withIncludeScala(false),
+    // Rewrite jakarta.servlet → javax.servlet in our bytecode so the artifact
+    // loads on Databricks Runtime 17.3, which ships javax instead of jakarta.
+    assembly / assemblyShadeRules := Seq(
+      ShadeRule.rename("jakarta.servlet.**" -> "javax.servlet.@1").inAll
+    ),
+    assembly / assemblyMergeStrategy := {
+      case PathList("META-INF", "services", xs @ _*) => MergeStrategy.concat
+      case PathList("META-INF", xs @ _*) => MergeStrategy.discard
+      case "application.conf" => MergeStrategy.concat
+      case "reference.conf" => MergeStrategy.concat
+      case _ => MergeStrategy.first
+    },
+
+    Compile / packageBin := assembly.value,
+    publishTo := {
+      if (isSnapshot.value)
+        Some("snapshots" at "https://central.sonatype.com/repository/maven-snapshots/")
+      else
+        sonatypePublishToBundle.value
+    }
+  )
+
 lazy val example_3_1_3 = (project in file("example_3_1_3"))
   .settings(
     name := "DataflintSparkExample313",

spark-plugin/clean-and-setup.sh

@@ -31,6 +31,10 @@ sbt pluginspark3/assembly
 echo "Building Spark 4 fat JAR..."
 sbt ++2.13.16 pluginspark4/assembly
 
+# Build Spark 4 Databricks fat JAR (jakarta.servlet → javax.servlet shaded)
+echo "Building Spark 4 Databricks fat JAR..."
+sbt ++2.13.16 pluginspark4databricks/assembly
+
 echo "✅ Setup complete!"
 echo ""
 echo "📋 Next steps:"
@@ -40,4 +44,5 @@ echo ""
 echo "📦 Fat JARs created:"
 echo "- Spark 3.x: pluginspark3/target/scala-2.12/dataflint-spark3_2.12-0.9.7-SNAPSHOT.jar"
 echo "- Spark 4.x: pluginspark4/target/scala-2.13/dataflint-spark4_2.13-0.9.7-SNAPSHOT.jar"
+echo "- Spark 4 (Databricks): pluginspark4databricks/target/scala-2.13/dataflint-spark4-databricks_2.13-0.9.7-SNAPSHOT.jar"
 

spark-plugin/pluginspark4databricks/src/main/scala/org/apache/spark/dataflint/DataflintSparkUILoader.scala

@@ -0,0 +1,22 @@
+package org.apache.spark.dataflint
+
+import org.apache.spark.SparkContext
+import org.apache.spark.dataflint.api.Spark4DatabricksPageFactory
+import org.apache.spark.ui.SparkUI
+
+/**
+ * Databricks variant of the Spark 4 loader. Identical to the pluginspark4
+ * loader except it instantiates [[Spark4DatabricksPageFactory]], which
+ * inverts the Databricks UI gate so the shaded jar serves UI only on DBR.
+ * Same FQN as the upstream loader so the shared SparkDataflintPlugin
+ * entrypoint resolves it without any per-flavor wiring.
+ */
+object DataflintSparkUILoader {
+  private val pageFactory = new Spark4DatabricksPageFactory()
+
+  def install(context: SparkContext): String =
+    new org.apache.spark.dataflint.DataflintSparkUICommonInstaller().install(context, pageFactory)
+
+  def loadUI(ui: SparkUI): String =
+    new org.apache.spark.dataflint.DataflintSparkUICommonInstaller().loadUI(ui, pageFactory)
+}

spark-plugin/pluginspark4databricks/src/main/scala/org/apache/spark/dataflint/api/Spark4DatabricksPageFactory.scala

@@ -0,0 +1,16 @@
+package org.apache.spark.dataflint.api
+
+import org.apache.spark.ui.SparkUI
+
+/**
+ * Databricks variant of [[Spark4PageFactory]]. The parent class skips the
+ * DataFlint UI on any Databricks runtime to avoid the jakarta.servlet
+ * NoClassDefFoundError on DBR 17.3 (see issue #47). This subclass inverts
+ * the check: enable UI ONLY on Databricks (where the javax-shaded bytecode
+ * matches the runtime). If this jar is installed on stock Spark 4 by
+ * mistake, the UI is silently skipped instead of crashing.
+ */
+class Spark4DatabricksPageFactory extends Spark4PageFactory {
+  override def isUISupported(ui: SparkUI): Boolean =
+    ui.conf.getOption("spark.databricks.clusterUsageTags.cloudProvider").isDefined
+}