CODEWITHSUNDEEP
c#.netapache-kafkaconfluent-platform
MSE
MSE

Reputation: 685

How can I list Kafka consumer groups using Confluent's .NET Client

I have installed Kafka on my development windows machine (kafka_2.11-2.4.0.tgz). It all works fine and I'm able to send and receive messages using the sample batch scripts.

Trying to build a C# windows application, I'm using Confluent's .NET Client for Apache Kafka (version 1.3.0.0) on a C# windows application. However when I'm using the sample given by Confluent to list the group subscriptions I'm getting the error System.ArgumentNullException: 'Argument 'group' must not be null. Parameter name: group' but there is no such argument that I pass into the method. Here's the code sample:

private static string ListConsumerGroups(string bootstrapServers) {
    string s = ($"Consumer Groups:"); 
    using (var adminClient = new AdminClientBuilder(new AdminClientConfig { BootstrapServers = bootstrapServers }).Build()) {
        var groups = adminClient.ListGroups(TimeSpan.FromSeconds(10));
        foreach (var g in groups) {
            s += "\r\n" + ($"  Group: {g.Group} {g.Error} {g.State}");
            s += "\r\n" + ($"  Broker: {g.Broker.BrokerId} {g.Broker.Host}:{g.Broker.Port}");
            s += "\r\n" + ($"  Protocol: {g.ProtocolType} {g.Protocol}");
            s += "\r\n" + ($"  Members:");
            foreach (var m in g.Members) {
                s += "\r\n" + ($"    {m.MemberId} {m.ClientId} {m.ClientHost}");
                s += "\r\n" + ($"    Metadata: {m.MemberMetadata.Length} bytes");
                s += "\r\n" + ($"    Assignment: {m.MemberAssignment.Length} bytes");
            }
        }
    }
    return s;
}

The code fails when making the call to adminClient.ListGroups with the timespan argument (no other arguments allowed into this method). I dont understand whether there is a bug in the API or I'm just missing something. When using the batch scripts to list the consumer group I do get a valid answer back.

> kafka-consumer-groups.bat --list --bootstrap-server "localhost:9092"

Upvotes: 2

Views: 2096

Answers (1)

Matt Howlett
Matt Howlett

Reputation: 491

this was a regression introduced in v1.3.0. It's resolved in v1.4.0-RC1 and later.

Upvotes: 3

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