Make some configuration properties optional

config.yaml.example

@@ -260,26 +260,27 @@ savepoints:
   # Interval in which savepoints will be created
   intervalSeconds: 300
 
-# Column renaming configuration. If you'd like to rename any columns, specify them like so:
+# Optional - Column renaming configuration. If you'd like to rename any columns, specify them like so:
 # - from: source_column_name
 #   to: dest_column_name
-renames: []
-# Which token ranges to skip. You shouldn't need to fill this in normally; the migrator will
-# create a savepoint file with this filled.
-skipTokenRanges: []
+# renames: []
 
-# Configuration section for running the validator. The validator is run manually (see README).
-validation:
-  # Should WRITETIMEs and TTLs be compared?
-  compareTimestamps: true
-  # What difference should we allow between TTLs?
-  ttlToleranceMillis: 60000
-  # What difference should we allow between WRITETIMEs?
-  writetimeToleranceMillis: 1000
-  # How many differences to fetch and print
-  failuresToFetch: 100
-  # What difference should we allow between floating point numbers?
-  floatingPointTolerance: 0.001
-  # What difference in ms should we allow between timestamps?
-  timestampMsTolerance: 0
+# Optional - Which token ranges to skip. You shouldn't need to fill this in normally; the migrator will
+# create a savepoint file with this filled.
+# skipTokenRanges: []
 
+# Configuration section for running the validator. The validator is run manually (see documentation).
+# Mandatory if the application is executed in validation mode.
+# validation:
+#   # Should WRITETIMEs and TTLs be compared?
+#   compareTimestamps: true
+#   # What difference should we allow between TTLs?
+#   ttlToleranceMillis: 60000
+#   # What difference should we allow between WRITETIMEs?
+#   writetimeToleranceMillis: 1000
+#   # How many differences to fetch and print
+#   failuresToFetch: 100
+#   # What difference should we allow between floating point numbers?
+#   floatingPointTolerance: 0.001
+#   # What difference in ms should we allow between timestamps?
+#   timestampMsTolerance: 0

docs/source/configuration.rst

@@ -26,16 +26,16 @@ The configuration file requires the following top-level properties (ie, with no
   # Target configuration
   target:
     # ...
-  # Columns to rename
+  # Optional - Columns to rename
   renames:
     # ...
   # Savepoints configuration
   savepoints:
     # ...
-  # Validator configuration
+  # Validator configuration. Required only if the app is executed in validation mode.
   validation:
     # ...
-  # Used internally
+  # Optional- Used internally
   skipTokenRanges: []
 
 These top-level properties are documented in the following sections (except ``skipTokenRanges``, which is used internally).
@@ -319,7 +319,7 @@ DynamoDB Target
 Renames
 -------
 
-The ``renames`` property lists the item columns to rename along the migration. To not rename any columns, use the empty array ``renames: []``.
+The optional ``renames`` property lists the item columns to rename along the migration.
 
 .. code-block:: yaml
 
@@ -347,7 +347,7 @@ When migrating data over CQL-compatible storages, the migrator is able to resume
 Validation
 ----------
 
-The properties of the ``validation`` field are used only when the application is executed in :doc:`validation mode </validate>`.
+The ``validation`` field and its properties are mandatory only when the application is executed in :doc:`validation mode </validate>`.
 
 .. code-block:: yaml
 

docs/source/rename-columns.rst

@@ -13,3 +13,5 @@ Indicate in the migration configuration which columns to rename with the ``renam
       to: bar
     - from: xxx
       to: yyy
+
+To not perform any renames, leave out the ``renames`` property from the configuration file.

migrator/src/main/scala/com/scylladb/migrator/Migrator.scala

@@ -36,7 +36,7 @@ object Migrator {
             spark,
             cassandraSource,
             cassandraSource.preserveTimestamps,
-            migratorConfig.skipTokenRanges)
+            migratorConfig.getSkipTokenRangesOrEmptySet)
           ScyllaMigrator.migrate(migratorConfig, scyllaTarget, sourceDF)
         case (parquetSource: SourceSettings.Parquet, scyllaTarget: TargetSettings.Scylla) =>
           val sourceDF = readers.Parquet.readDataFrame(spark, parquetSource)

migrator/src/main/scala/com/scylladb/migrator/alternator/AlternatorValidator.scala

@@ -49,7 +49,8 @@ object AlternatorValidator {
 
     // Define some aliases to prevent the Spark engine to try to serialize the whole object graph
     val renamedColumn = config.renamesMap
-    val configValidation = config.validation
+    val configValidation = config.validation.getOrElse(
+      sys.error("Missing required property 'validation' in the configuration file."))
 
     val targetByKey: RDD[(List[DdbValue], collection.Map[String, DdbValue])] =
       target
@@ -74,7 +75,7 @@ object AlternatorValidator {
             configValidation.floatingPointTolerance
           )
       }
-      .take(config.validation.failuresToFetch)
+      .take(configValidation.failuresToFetch)
       .toList
   }
 

migrator/src/main/scala/com/scylladb/migrator/config/MigratorConfig.scala

@@ -10,15 +10,20 @@ import io.circe.{ Decoder, DecodingFailure, Encoder, Error, Json }
 
 case class MigratorConfig(source: SourceSettings,
                           target: TargetSettings,
-                          renames: List[Rename],
+                          renames: Option[List[Rename]],
                           savepoints: Savepoints,
-                          skipTokenRanges: Set[(Token[_], Token[_])],
-                          validation: Validation) {
+                          skipTokenRanges: Option[Set[(Token[_], Token[_])]],
+                          validation: Option[Validation]) {
   def render: String = this.asJson.asYaml.spaces2
 
+  def getRenamesOrNil: List[Rename] = renames.getOrElse(Nil)
+
   /** The list of renames modelled as a Map from the old column name to the new column name */
   lazy val renamesMap: Map[String, String] =
-    renames.map(rename => rename.from -> rename.to).toMap.withDefault(identity)
+    getRenamesOrNil.map(rename => rename.from -> rename.to).toMap.withDefault(identity)
+
+  def getSkipTokenRangesOrEmptySet: Set[(Token[_], Token[_])] = skipTokenRanges.getOrElse(Set.empty)
+
 }
 object MigratorConfig {
   implicit val tokenEncoder: Encoder[Token[_]] = Encoder.instance {

migrator/src/main/scala/com/scylladb/migrator/scylla/ScyllaMigrator.scala

@@ -76,7 +76,7 @@ object ScyllaMigrator {
         log.info(
           "Savepoints array defined, size of the array: " + migratorConfig.skipTokenRanges.size)
 
-        val diff = allTokenRanges.diff(migratorConfig.skipTokenRanges)
+        val diff = allTokenRanges.diff(migratorConfig.getSkipTokenRangesOrEmptySet)
         log.info("Diff ... total diff of full ranges to savepoints is: " + diff.size)
         log.debug("Dump of the missing tokens: ")
         log.debug(diff)
@@ -88,7 +88,7 @@ object ScyllaMigrator {
     try {
       writers.Scylla.writeDataframe(
         target,
-        migratorConfig.renames,
+        migratorConfig.getRenamesOrNil,
         sourceDF.dataFrame,
         sourceDF.timestampColumns,
         tokenRangeAccumulator)
@@ -147,7 +147,7 @@ object ScyllaMigrator {
       (range.range.start.asInstanceOf[Token[_]], range.range.end.asInstanceOf[Token[_]]))
 
     val modifiedConfig = config.copy(
-      skipTokenRanges = config.skipTokenRanges ++ rangesToSkip
+      skipTokenRanges = Some(config.getSkipTokenRangesOrEmptySet ++ rangesToSkip)
     )
 
     Files.write(filename, modifiedConfig.render.getBytes(StandardCharsets.UTF_8))

migrator/src/main/scala/com/scylladb/migrator/scylla/ScyllaValidator.scala

@@ -25,6 +25,11 @@ object ScyllaValidator {
     sourceSettings: SourceSettings.Cassandra,
     targetSettings: TargetSettings.Scylla,
     config: MigratorConfig)(implicit spark: SparkSession): List[RowComparisonFailure] = {
+
+    val validationConfig =
+      config.validation.getOrElse(
+        sys.error("Missing required property 'validation' in the configuration file."))
+
     val sourceConnector: CassandraConnector =
       Connectors.sourceConnector(spark.sparkContext.getConf, sourceSettings)
     val targetConnector: CassandraConnector =
@@ -118,14 +123,14 @@ object ScyllaValidator {
           RowComparisonFailure.compareCassandraRows(
             l,
             r,
-            config.validation.floatingPointTolerance,
-            config.validation.timestampMsTolerance,
-            config.validation.ttlToleranceMillis,
-            config.validation.writetimeToleranceMillis,
-            config.validation.compareTimestamps
+            validationConfig.floatingPointTolerance,
+            validationConfig.timestampMsTolerance,
+            validationConfig.ttlToleranceMillis,
+            validationConfig.writetimeToleranceMillis,
+            validationConfig.compareTimestamps
           )
       }
-      .take(config.validation.failuresToFetch)
+      .take(validationConfig.failuresToFetch)
       .toList
 
   }

tests/src/test/configurations/cassandra-to-scylla-basic.yaml

@@ -28,12 +28,10 @@ target:
   connections: 16
   stripTrailingZerosForDecimals: false
 
-renames: []
-
 savepoints:
   path: /app/savepoints
   intervalSeconds: 300
-skipTokenRanges: []
+
 validation:
   compareTimestamps: true
   ttlToleranceMillis: 60000

tests/src/test/configurations/cassandra-to-scylla-renames.yaml

@@ -35,11 +35,3 @@ renames:
 savepoints:
   path: /app/savepoints
   intervalSeconds: 300
-skipTokenRanges: []
-validation:
-  compareTimestamps: true
-  ttlToleranceMillis: 60000
-  writetimeToleranceMillis: 1000
-  failuresToFetch: 100
-  floatingPointTolerance: 0.001
-  timestampMsTolerance: 0

tests/src/test/configurations/dynamodb-s3-export-to-alternator-basic.yaml

@@ -30,17 +30,7 @@ target:
     secretKey: dummy
   streamChanges: false
 
-renames: []
-
 # Below are unused but mandatory settings
 savepoints:
   path: /app/savepoints
   intervalSeconds: 300
-skipTokenRanges: []
-validation:
-  compareTimestamps: true
-  ttlToleranceMillis: 60000
-  writetimeToleranceMillis: 1000
-  failuresToFetch: 100
-  floatingPointTolerance: 0.001
-  timestampMsTolerance: 0

tests/src/test/configurations/dynamodb-to-alternator-basic.yaml

@@ -21,13 +21,11 @@ target:
     secretKey: dummy
   streamChanges: false
 
-renames: []
-
 # Below are unused but mandatory settings
 savepoints:
   path: /app/savepoints
   intervalSeconds: 300
-skipTokenRanges: []
+
 validation:
   compareTimestamps: true
   ttlToleranceMillis: 60000

tests/src/test/configurations/dynamodb-to-alternator-issue-103.yaml

@@ -24,17 +24,7 @@ target:
   maxMapTasks: 1
   streamChanges: false
 
-renames: []
-
 # Below are unused but mandatory settings
 savepoints:
   path: /app/savepoints
   intervalSeconds: 300
-skipTokenRanges: []
-validation:
-  compareTimestamps: true
-  ttlToleranceMillis: 60000
-  writetimeToleranceMillis: 1000
-  failuresToFetch: 100
-  floatingPointTolerance: 0.001
-  timestampMsTolerance: 0

tests/src/test/configurations/dynamodb-to-alternator-renames.yaml

@@ -31,11 +31,3 @@ renames:
 savepoints:
   path: /app/savepoints
   intervalSeconds: 300
-skipTokenRanges: []
-validation:
-  compareTimestamps: true
-  ttlToleranceMillis: 60000
-  writetimeToleranceMillis: 1000
-  failuresToFetch: 100
-  floatingPointTolerance: 0.001
-  timestampMsTolerance: 0

tests/src/test/configurations/parquet-to-scylla-basic.yaml

@@ -16,16 +16,6 @@ target:
   connections: 16
   stripTrailingZerosForDecimals: false
 
-renames: []
-
 savepoints:
   path: /app/savepoints
   intervalSeconds: 300
-skipTokenRanges: []
-validation:
-  compareTimestamps: true
-  ttlToleranceMillis: 60000
-  writetimeToleranceMillis: 1000
-  failuresToFetch: 100
-  floatingPointTolerance: 0.001
-  timestampMsTolerance: 0

tests/src/test/configurations/scylla-to-scylla-basic.yaml

@@ -28,16 +28,6 @@ target:
   connections: 16
   stripTrailingZerosForDecimals: false
 
-renames: []
-
 savepoints:
   path: /app/savepoints
   intervalSeconds: 300
-skipTokenRanges: []
-validation:
-  compareTimestamps: true
-  ttlToleranceMillis: 60000
-  writetimeToleranceMillis: 1000
-  failuresToFetch: 100
-  floatingPointTolerance: 0.001
-  timestampMsTolerance: 0