#476 Allow configuring maximum length of error messages in email notifications

pramen/core/src/main/resources/reference.conf

@@ -168,6 +168,15 @@ pramen {
   # one transformer are different from partitions produced by other transformers.
   # You can set it to false to have a more strict setup and disallow this behavior.
   enable.multiple.jobs.per.output.table = true
+
+  # Limits on certain elements of notiications (email etc)
+  notifications {
+    # The maximum length in characters of the Reason field in the completed tasks table.
+    reason.max.length = 1024
+    # The maximum length of errors and exceptions in the notification body. The default value is selected
+    # so that Pramen can handle at least 100 exceptions in a single email notification.
+    exception.max.length = 65536
+  }
 }
 
 pramen.py {

pramen/core/src/main/scala/za/co/absa/pramen/core/notify/message/MessageBuilderHtml.scala

@@ -16,17 +16,20 @@
 
 package za.co.absa.pramen.core.notify.message
 
+import com.typesafe.config.Config
 import za.co.absa.pramen.api.notification.NotificationEntry.Paragraph
 import za.co.absa.pramen.api.notification.{Style, TableHeader, TextElement}
 import za.co.absa.pramen.core.exceptions.OsSignalException
-import za.co.absa.pramen.core.utils.ResourceUtils
+import za.co.absa.pramen.core.notify.pipeline.PipelineNotificationBuilderHtml.NOTIFICATION_EXCEPTION_MAX_LENGTH_KEY
+import za.co.absa.pramen.core.utils.{ConfigUtils, ResourceUtils}
 import za.co.absa.pramen.core.utils.StringUtils.{renderThreadDumps, renderThrowable}
 
 import scala.collection.mutable.ListBuffer
 import scala.compat.Platform.EOL
 
-class MessageBuilderHtml extends MessageBuilder {
+class MessageBuilderHtml(conf: Config) extends MessageBuilder {
   private val style = ResourceUtils.getResourceString("/email_template/style.css")
+  private val maxExceptionLength = ConfigUtils.getOptionInt(conf, NOTIFICATION_EXCEPTION_MAX_LENGTH_KEY)
   private val body = new ListBuffer[String]
 
   override def withParagraph(text: Seq[TextElement]): MessageBuilderHtml = {
@@ -73,7 +76,7 @@ class MessageBuilderHtml extends MessageBuilder {
         renderThreadDumps(signalException.threadStackTraces)
       case other =>
         withParagraph(Seq(TextElement(description, Style.Exception)))
-        renderThrowable(other)
+        renderThrowable(other, maximumLength = maxExceptionLength)
     }
 
     withUnformattedText(rendered)

pramen/core/src/main/scala/za/co/absa/pramen/core/notify/pipeline/PipelineNotificationBuilderHtml.scala

@@ -38,9 +38,13 @@ object PipelineNotificationBuilderHtml {
   val MIN_RPS_JOB_DURATION_SECONDS = 60
   val MIN_RPS_RECORDS = 1000
   val MIN_MEGABYTES = 10
+  val NOTIFICATION_REASON_MAX_LENGTH_KEY = "pramen.notifications.reason.max.length"
+  val NOTIFICATION_EXCEPTION_MAX_LENGTH_KEY = "pramen.notifications.exception.max.length"
 }
 
 class PipelineNotificationBuilderHtml(implicit conf: Config) extends PipelineNotificationBuilder {
+  import PipelineNotificationBuilderHtml._
+
   private val log = LoggerFactory.getLogger(this.getClass)
 
   private val timestampFmt: DateTimeFormatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm Z")
@@ -52,6 +56,9 @@ class PipelineNotificationBuilderHtml(implicit conf: Config) extends PipelineNot
   private var minRps = 0
   private var goodRps = Int.MaxValue
 
+  private val maxReasonLength = ConfigUtils.getOptionInt(conf, NOTIFICATION_REASON_MAX_LENGTH_KEY)
+  private val maxExceptionLength = ConfigUtils.getOptionInt(conf, NOTIFICATION_EXCEPTION_MAX_LENGTH_KEY)
+
   var appException: Option[Throwable] = None
   var warningFlag: Boolean = false
   var appName: String = "Unspecified Job"
@@ -131,7 +138,7 @@ class PipelineNotificationBuilderHtml(implicit conf: Config) extends PipelineNot
   }
 
   def renderBody(): String = {
-    val builder = new MessageBuilderHtml
+    val builder = new MessageBuilderHtml(conf)
 
     renderHeader(builder)
 
@@ -290,9 +297,16 @@ class PipelineNotificationBuilderHtml(implicit conf: Config) extends PipelineNot
         .withText(info.infoDate.toString, Style.Error)
     )
 
+    val errorMessage = ex.getMessage
+
+    val errorMessageTruncated = maxReasonLength match {
+      case Some(maxLength) if errorMessage.length > maxLength => errorMessage.substring(0, maxLength) + "..."
+      case _ => errorMessage
+    }
+
     paragraphBuilder
       .withText(" has failed with an exception: ", Style.Exception)
-      .withText(ex.getMessage, Style.Error)
+      .withText(errorMessageTruncated, Style.Error)
 
     builder.withParagraph(paragraphBuilder)
     renderException(builder, ex)
@@ -311,7 +325,7 @@ class PipelineNotificationBuilderHtml(implicit conf: Config) extends PipelineNot
         val stderrMsg = if (stderr.isEmpty) "" else s"""Last <b>stderr</b> lines:\n${stderr.mkString("", EOL, EOL)}"""
         s"$msg\n$stdoutMsg\n$stderrMsg"
       case ex: Throwable                     =>
-        renderThrowable(ex)
+        renderThrowable(ex, maximumLength = maxExceptionLength)
     }
 
     builder.withUnformattedText(text)
@@ -599,7 +613,7 @@ class PipelineNotificationBuilderHtml(implicit conf: Config) extends PipelineNot
   }
 
   private[core] def getFailureReason(task: TaskResult): String = {
-    task.runStatus.getReason match {
+    val reason = task.runStatus.getReason match {
       case Some(reason) => reason
       case None         =>
         if (task.dependencyWarnings.isEmpty) {
@@ -609,6 +623,11 @@ class PipelineNotificationBuilderHtml(implicit conf: Config) extends PipelineNot
           s"Optional dependencies failed for: $tables"
         }
     }
+
+    maxReasonLength match {
+      case Some(maxLength) if reason.length > maxLength =>  reason.substring(0, maxLength) + "..."
+      case _ => reason
+    }
   }
 
   private[core] def getFinishTime(task: TaskResult): String = {

pramen/core/src/main/scala/za/co/absa/pramen/core/utils/StringUtils.scala

@@ -169,14 +169,19 @@ object StringUtils {
   }
 
   /** Renders an exception as a string */
-  def renderThrowable(ex: Throwable, level: Int = 1): String = {
+  def renderThrowable(ex: Throwable, level: Int = 1, maximumLength: Option[Int] = None): String = {
     val prefix = " " * (level * 2)
     val base = s"""${ex.toString}\n${ex.getStackTrace.map(s => s"$prefix$s").mkString("", EOL, EOL)}"""
     val cause = Option(ex.getCause) match {
       case Some(c) if level < 6 => s"\n${prefix}Caused by " + renderThrowable(c, level + 1)
       case _                    => ""
     }
-    base + cause
+    val fullText = base + cause
+
+    maximumLength match {
+      case Some(len) if fullText.length > len => fullText.substring(0, len) + "..."
+      case _ => fullText
+    }
   }
 
   def renderThreadDumps(threadStackTraces: Seq[ThreadStackTrace]): String = {

pramen/core/src/test/scala/za/co/absa/pramen/core/tests/notify/message/MessageBuilderHtmlSuite.scala

@@ -16,6 +16,7 @@
 
 package za.co.absa.pramen.core.tests.notify.message
 
+import com.typesafe.config.ConfigFactory
 import org.scalatest.wordspec.AnyWordSpec
 import za.co.absa.pramen.api.notification.NotificationEntry.Paragraph
 import za.co.absa.pramen.api.notification.{Style, TableHeader, TextElement}
@@ -28,7 +29,7 @@ class MessageBuilderHtmlSuite extends AnyWordSpec with TextComparisonFixture {
     "render an email with the requested elements" in {
       val expected = ResourceUtils.getResourceString("/test/notify/expectedMessage.dat")
 
-      val builder = new MessageBuilderHtml
+      val builder = new MessageBuilderHtml(ConfigFactory.empty())
       val tb = new TableBuilderHtml
 
       val actual = builder