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Kafdrop

Kafdrop is a UI for monitoring Apache Kafka clusters. The tool displays information such as brokers, topics, partitions, and even lets you view messages. It is a light weight application that runs on Spring Boot and requires very little configuration.

Requirements

  • Java 8
  • Kafka 2.0 or later (might work with earlier versions)
  • Zookeeper (3.4.5 or later)

Optional, additional integration:

  • Schema Registry

Building

After cloning the repository, building should just be a matter of running a standard Maven build:

$ mvn clean package

Running Stand Alone

The build process creates an executable JAR file.

java -jar ./target/kafdrop-<version>.jar --zookeeper.connect=<host:port>,<host:port>,... --kafka.brokers=<host:port>,<host:port>,...

Then open a browser and navigate to http://localhost:9000. The port can be overridden by adding the following config:

    --server.port=<port>

Additionally, you can optionally configure a schema registry connection with:

    --schemaregistry.connect=http://localhost:8081

Finally, a default message format (e.g. to deserialize Avro messages) can optionally be configured as follows:

    --message.format=AVRO

Valid format values are "DEFAULT" and "AVRO". This setting can also be configured at the topic level via dropdown when viewing messages.

Running with Docker

Note for Mac Users: You need to convert newline formatting of the kafdrop.sh file before running this command:

    dos2unix src/main/docker/*

The following maven command will generate a Docker image:

    mvn clean package assembly:single docker:build

Once the build finishes you can launch the image as follows:

    docker run -d -p 9000:9000 -e ZOOKEEPER_CONNECT=<host:port,host:port> kafdrop

And access the UI at http://localhost:9000.

Configuration Options

Option Default Description
kafka.truststoreLocation Location of the truststore used for secure connections
kafka.keystoreLocation Location of the keystore used for secure connections
kafka.additionalProperties. Additional properties to pass to the Admin or Consumer clients
kafka.adminPool.minIdle 0 Minimum number of unused admin clients to keep open
kafka.adminPool.maxIdle 8 Maximum number of unused admin clients to keep open
kafka.adminPool.maxTotal 8 Maximum number of admin clients to have open at one time
kafka.adminPool.maxWaitMillis -1 Milliseconds to wait for an admin client from the pool (-1 == forever)
kafka.consumerPool.minIdle 0 Minimum number of unused consumer clients to keep open
kafka.consumerPool.maxIdle 8 Maximum number of unused consumer clients to keep open
kafka.consumerPool.maxTotal 8 Maximum number of consumer clients to have open at one time
kafka.consumerPool.maxWaitMillis -1 Millis to wait for a consumer client from the pool (-1 == forever)

Kafka APIs

Starting with version 2.0.0, Kafdrop offers a set of Kafka APIs that mirror the existing HTML views. Any existing endpoint can be returned as JSON by simply setting the Accept : application/json header. There are also two endpoints that are JSON only:

/topic : Returns array of all topic names
/topic/{topicName}/{consumerId} : Return partition offset and lag details for a specific topic and consumer.

Swagger

To help document the Kafka APIs, Swagger has been included. The Swagger output is available by default at the following Kafdrop URL:

/v2/api-docs

However this can be overridden with the following configuration:

springfox.documentation.swagger.v2.path=/new/swagger/path

Currently only the JSON endpoints are included in the Swagger output; the HTML views and Spring Boot debug endpoints are excluded.

You can disable Swagger output with the following configuration:

swagger.enabled=false

CORS Headers

Starting in version 2.0.0, Kafdrop sets CORS headers for all endpoints. You can control the CORS header values with the following configurations:

cors.allowOrigins (default is *)
cors.allowMethods (default is GET,POST,PUT,DELETE)
cors.maxAge (default is 3600)
cors.allowCredentials (default is true)
cors.allowHeaders (default is Origin,Accept,X-Requested-With,Content-Type,Access-Control-Request-Method,Access-Control-Request-Headers,Authorization)

You can also disable CORS entirely with the following configuration:

cors.enabled=false