Styjun

My database is in another Linux node lets suppose xxx.xx.xxx.xxx:3306 and I am running the standalone command of kafka connect from my Windows machine. My server.properties code is

name=test-source-mysql-jdbc-autoincrement
connector.class=io.confluent.connect.jdbc.JdbcSourceConnector
tasks.max=1
connection.url=jdbc:mysql://xxx.xx.xxx.xxx:3306/databasename?user=username&useSSL=false
&password=password
mode=incrementing
incrementing.column.name=columnname 
topic.prefix=mysqlname-databasename-database- 

I am Receiving the following error

Mar 28, 2019 11:55:41 AM org.glassfish.jersey.internal.inject.Providers checkProviderRuntime
WARNING: A provider org.apache.kafka.connect.runtime.rest.resources.ConnectorPluginsResource registered in SERVER runtime does not implement any provider interfaces applicable in the SERVER runtime. D
ue to constraint configuration problems the provider org.apache.kafka.connect.runtime.rest.resources.ConnectorPluginsResource will be ignored.
Mar 28, 2019 11:55:41 AM org.glassfish.jersey.internal.inject.Providers checkProviderRuntime
WARNING: A provider org.apache.kafka.connect.runtime.rest.resources.ConnectorsResource registered in SERVER runtime does not implement any provider interfaces applicable in the SERVER runtime. Due to
constraint configuration problems the provider org.apache.kafka.connect.runtime.rest.resources.ConnectorsResource will be ignored.
Mar 28, 2019 11:55:41 AM org.glassfish.jersey.internal.inject.Providers checkProviderRuntime
WARNING: A provider org.apache.kafka.connect.runtime.rest.resources.RootResource registered in SERVER runtime does not implement any provider interfaces applicable in the SERVER runtime. Due to constr
aint configuration problems the provider org.apache.kafka.connect.runtime.rest.resources.RootResource will be ignored.
Mar 28, 2019 11:55:41 AM org.glassfish.jersey.internal.Errors logErrors
WARNING: The following warnings have been detected: WARNING: The (sub)resource method createConnector in org.apache.kafka.connect.runtime.rest.resources.ConnectorsResource contains empty path annotati
on.
WARNING: The (sub)resource method listConnectors in org.apache.kafka.connect.runtime.rest.resources.ConnectorsResource contains empty path annotation.
WARNING: The (sub)resource method listConnectorPlugins in org.apache.kafka.connect.runtime.rest.resources.ConnectorPluginsResource contains empty path annotation.
WARNING: The (sub)resource method serverInfo in org.apache.kafka.connect.runtime.rest.resources.RootResource contains empty path annotation.

[2019-03-28 11:55:42,108] ERROR Stopping after connector error (org.apache.kafka.connect.cli.ConnectStandalone)
java.lang.IllegalArgumentException: Number of groups must be positive.
 at org.apache.kafka.connect.util.ConnectorUtils.groupPartitions(ConnectorUtils.java:41)
 at io.confluent.connect.jdbc.JdbcSourceConnector.taskConfigs(JdbcSourceConnector.java:148)
 at org.apache.kafka.connect.runtime.Worker.connectorTaskConfigs(Worker.java:305)
 at org.apache.kafka.connect.runtime.standalone.StandaloneHerder.recomputeTaskConfigs(StandaloneHerder.java:307)
 at org.apache.kafka.connect.runtime.standalone.StandaloneHerder.updateConnectorTasks(StandaloneHerder.java:333)
 at org.apache.kafka.connect.runtime.standalone.StandaloneHerder.putConnectorConfig(StandaloneHerder.java:211)
 at org.apache.kafka.connect.cli.ConnectStandalone.main(ConnectStandalone.java:107)

Any help is appreciated.

The error Number of groups must be positive. indicates that Kafka Connect JDBC source has not found any tables/objects to fetch from the database. Looking at your config, you've not specified table.whitelist / table.blacklist so that could be why. Another reason would be if the user is not authorised to select from any of the available objects. This article goes into more detail.