SPNEGO Auth in Scala / Java

build.sbt

ThisBuild / name := "KerberosTest"
ThisBuild / organization := "com.example"
ThisBuild / version := "0.0.1-SNAPSHOT"
ThisBuild / scalaVersion := "2.11.12"

libraryDependencies ++=  List(
  "org.apache.spark" %% "spark-core" % "2.4.7" % "provided",
  "org.apache.spark" %% "spark-sql" % "2.4.7" % "provided",
  "org.springframework.security.kerberos" % "spring-security-kerberos-client" % "1.0.1.RELEASE"
)

mainClass in assembly := Some("com.example.SparkApp")

assemblyMergeStrategy in assembly := {
  case x if Assembly.isConfigFile(x) =>
    MergeStrategy.concat
  case PathList(ps @ _*) if Assembly.isReadme(ps.last) || Assembly.isLicenseFile(ps.last) =>
    MergeStrategy.rename
  case PathList("META-INF", xs @ _*) =>
    (xs map {_.toLowerCase}) match {
      case ("manifest.mf" :: Nil) | ("index.list" :: Nil) | ("dependencies" :: Nil) =>
        MergeStrategy.discard
      case ps @ (x :: xs) if ps.last.endsWith(".sf") || ps.last.endsWith(".dsa") =>
        MergeStrategy.discard
      case "plexus" :: xs =>
        MergeStrategy.discard
      case "services" :: xs =>
        MergeStrategy.filterDistinctLines
      case ("spring.schemas" :: Nil) | ("spring.handlers" :: Nil) =>
        MergeStrategy.filterDistinctLines
      case _ => MergeStrategy.first
    }
  case _ => MergeStrategy.first
}

plugins.sbt

addSbtPlugin("com.eed3si9n" % "sbt-assembly" % "0.14.10")

SparkApp.scala

import org.apache.spark.sql.SparkSession
import org.slf4j.LoggerFactory
import sun.security.krb5.internal.ktab.KeyTab
import org.springframework.security.kerberos.client.KerberosRestTemplate

object SparkApp {
  def main(args: Array[String]) {
    // Spark session is obsolete, but I needed it to test it as a spark app
    val spark = SparkSession.builder.appName("KerberosTest Spark Job").getOrCreate()
    val logger = LoggerFactory.getLogger(this.getClass)

    val keytabPath = args(0) // "keytab path"
    logger.info(s"Keytab path $keytabPath")

    val url = args(1) // SPNEGO entry point
    logger.info(s"URL $url")

    val keytab = KeyTab.getInstance(keytabPath) // "Validate" the keytab 
    val username = keytab.getOneName.getName // Get name from keytab, just to be sure
    logger.info(s"Username $username")
    
    val restTemplate = new KerberosRestTemplate(keytabPath, username)

    val response = restTemplate.getForEntity(url, classOf[String]) // Pull headers from this response
    val statusCode = response.getStatusCode

    logger.info(response.getBody)
    logger.info("--statusCode--")
    logger.info(statusCode.toString)
    logger.info("--statusCode--")

    spark.stop()
  }
}