Current state: Accepted
Discussion thread: here
JIRA: here
Currently there is a way to pass a KafkaClientSupplier
in KafkaStreams
constructor. This KIP proposes to add a public config in StreamsConfig
to pass the class through config and use reflection to create
a new KafkaClientSupplier
object. The major motivation is to allow existing KafkaStreams applications to upgrade without application code changes. Note that if existing KafkaStreams applications want to
use a customized KafkaClientSupplier
, they may still need to add required dependencies.
We will add a public field in StreamsConfig
called default.client.supplier
to configure the KafkaClientSupplier
we use in KafkaStreams. The default value of the config will the classname
of DefaultKafkaClientSupplier
.
We will also add a new public method in StreamsConfig
called getKafkaClientSupplier
. It will return KafkaClientSupplier
based on the config.
In KafkaStreams
constructor, we will read the value of default.client.supplier
from StreamsConfig
. We will use reflection to create an object of given class and throw
an exception if the class type isn't KafkaClientSupplier
. If user provides both the config and supply KafkaClientSupplier
in KafkaStreams
constructor, the config will be ignored and supplied
KafkaClientSupplier
will be used.
There will be no compatibility, deprecation and migration issues.
Unit test can capture the changes in this KIP. We can test happy path where object can be created successfully and exception case where class couldn't be found or type is wrong.
An alternative is that we don't need this change and user can use KafkaStreams
constructor to supply any KafkaClientSupplier
since it's a public constructor.
The benefits of this alternative are:
KafkaClientSupplier
KafkaStreams
can have a different KafkaClientSupplier
The downsides of this alternative are:
KafkaStreams
constructor call in order to use a new KafkaClientSupplier
.So to cater for users who don't want to update their source code, we are proposing to add this config option as well.