CDC: Fix validation logic for configs related to parallel streaming (#173)

This PR fixes the bug while validating the parallel streaming
configuration properties and instead of using a common method to
validate, we now specify the lambda method directly at the time of
`Field` declaration.

Author: vaibhav-yb

debezium-connector-postgres/src/main/java/io/debezium/connector/postgresql/PostgresConnectorConfig.java

@@ -740,19 +740,37 @@ public static SchemaRefreshMode parse(String value) {
             .withDisplayName("Slot names for parallel consumption")
             .withImportance(Importance.LOW)
             .withDescription("Comma separated values for multiple slot names")
-            .withValidation(PostgresConnectorConfig::validateUsageWithParallelStreamingMode);
+            .withValidation((config, field, output) -> {
+                if (!config.getString(field, "").isEmpty() && !config.getString(STREAMING_MODE).equalsIgnoreCase("parallel")) {
+                    output.accept(field, "", "slot.names is only valid with streaming.mode 'parallel'");
+                    return 1;
+                }
+                return 0;
+            });
 
     public static final Field PUBLICATION_NAMES = Field.create("publication.names")
             .withDisplayName("Publication names for parallel consumption")
             .withImportance(Importance.LOW)
             .withDescription("Comma separated values for multiple publication names")
-            .withValidation(PostgresConnectorConfig::validateUsageWithParallelStreamingMode);
+            .withValidation((config, field, output) -> {
+                if (!config.getString(field, "").isEmpty() && !config.getString(STREAMING_MODE).equalsIgnoreCase("parallel")) {
+                    output.accept(field, "", "publication.names is only valid with streaming.mode 'parallel'");
+                    return 1;
+                }
+                return 0;
+            });
 
     public static final Field SLOT_RANGES = Field.create("slot.ranges")
             .withDisplayName("Ranges on which a slot is supposed to operate")
             .withImportance(Importance.LOW)
             .withDescription("Semi-colon separated values for hash ranges to be polled by tasks.")
-            .withValidation(PostgresConnectorConfig::validateUsageWithParallelStreamingMode);
+            .withValidation((config, field, output) -> {
+                if (!config.getString(field, "").isEmpty() && !config.getString(STREAMING_MODE).equalsIgnoreCase("parallel")) {
+                    output.accept(field, "", "slot.ranges is only valid with streaming.mode 'parallel'");
+                    return 1;
+                }
+                return 0;
+            });
 
     public static final Field YB_LOAD_BALANCE_CONNECTIONS = Field.create("yb.load.balance.connections")
             .withDisplayName("YB load balance connections")
@@ -1580,16 +1598,4 @@ protected static int validateYBHostname(Configuration config, Field field, Field
 
         return problemCount;
     }
-
-    protected static int validateUsageWithParallelStreamingMode(Configuration config, Field field, Field.ValidationOutput problems) {
-        String mode = config.getString(STREAMING_MODE);
-        int problemCount = 0;
-
-        if (!StreamingMode.parse(mode).isParallel()) {
-            problems.accept(field, config.getString(field), "Configuration is only valid with parallel streaming mode");
-            ++problemCount;
-        }
-
-        return problemCount;
-    }
 }

debezium-connector-postgres/src/main/java/io/debezium/connector/postgresql/YugabyteDBConnector.java

@@ -144,6 +144,13 @@ public List<Map<String, String>> taskConfigs(int maxTasks) {
 
         // YB Note: Only applicable when snapshot mode is not parallel.
         // this will always have just one task with the given list of properties
+
+        // This is to ensure that whenever the connector runs with a single task model,
+        // the default task ID is populated as this is not done by debezium-core.
+        if (props != null) {
+            props.put(PostgresConnectorConfig.TASK_ID, "0");
+        }
+
         return props == null ? Collections.emptyList() : Collections.singletonList(new HashMap<>(props));
     }
 

debezium-connector-postgres/src/test/java/io/debezium/connector/postgresql/PostgresConnectorConfigDefTest.java

@@ -103,10 +103,22 @@ public void shouldFailIfSlotRangesSpecifiedWithoutParallelStreamingMode() {
                 .with(PostgresConnectorConfig.STREAMING_MODE, PostgresConnectorConfig.StreamingMode.DEFAULT)
                 .with(PostgresConnectorConfig.SLOT_RANGES, "0,10;10,65536");
 
-        int problemCount = PostgresConnectorConfig.validateUsageWithParallelStreamingMode(
-          configBuilder.build(), PostgresConnectorConfig.SLOT_RANGES, (field, value, problemMessage) -> System.out.println(problemMessage));
+        boolean valid = PostgresConnectorConfig.SLOT_RANGES.validate(
+                configBuilder.build(), (field, value, problemMessage) -> System.out.println(problemMessage));
 
-        assertThat(problemCount == 1).isTrue();
+        assertThat(valid).isFalse();
+    }
+
+    @Test
+    public void ensureNoErrorWhenProperParallelStreamingConfigSpecified() {
+        Configuration.Builder configBuilder = TestHelper.defaultConfig()
+                .with(PostgresConnectorConfig.STREAMING_MODE, PostgresConnectorConfig.StreamingMode.PARALLEL)
+                .with(PostgresConnectorConfig.SLOT_RANGES, "0,10;10,65536");
+
+        boolean valid = PostgresConnectorConfig.SLOT_RANGES.validate(
+                configBuilder.build(), (field, value, problemMessage) -> System.out.println(problemMessage));
+
+        assertThat(valid).isTrue();
     }
 
     public void validateCorrectHostname(boolean multiNode) {