Agent Groups

How to split Agents for a cluster into different "groups".

Agent Groups

Agent Groups are distinct sets of Agents that all belong to the same logical cluster. Groups enable a single logical cluster to be split into many different "groups" that are isolated at the network / service discovery layer.

For example, consider the scenario where a single logical WarpStream cluster is "flexed" across multiple VPCs, regions, or even cloud providers:

In the diagram above producer and consumer clients running in vpc_1 will only ever connect to Agents running in group_vpc_1. Similarly, producers and consumer running in vpc_2 will only ever connect to Agents running in group_vpc_2. However, since both Agent Groups belong to the same logical virtual cluster and have access to the same object storage bucket, clients in each VPC will be able to write and read data for all topics and partitions, even those that were created by clients / Agents running in a completely different VPC!

Agent groups are a powerful abstraction that enable a variety of use-cases:

1. Isolating specific producers or consumers to dedicated Agent Groups to avoid noisy neighbors.

2. "Flexing" a single logical cluster across multiple VPCs, regions, or even clouds providers without resorting to complex VPC peering setups.

Configuring Agent Goups

Configuring Agent Groups is simple. Just add the -agentGroup $GROUP_NAME flag to your Agent deployment. For example, if you wanted to flex a single logical WarpStream cluster across two Kubernetes clusters running in different VPCs:

# In Kubernetes cluster 1
warpstream agent -virtualClusterID $CLUSTER_ID -agentGroup group-1

# In Kubernetes cluster 2
warpstream agent -virtualClusterID $CLUSTER_ID -agentGroup group-2

Alternatively, you can set the WARPSTREAM_AGENT_GROUP environment variable instead.

Agent group names may only contain lowercase letters, numbers, and dashes (-).

Targeting Agent Groups

When your Kafka (or Schema Registry) client connects to an Agent in a specific group, the WarpStream service discovery system will ensure that your client only connects to other Agents in the same group. This means that in order to take advantage of the Agent group functionality, you need to ensure that the bootstrap URL you configure in your client will only ever resolve to Agents in the correct group.

Kubernetes

Targeting specific Agent Groups in Kubernetes is easy. Each Agent group will have its own helm deployment, and therefore its own Kubernetes service. Use the Kubernetes service name that corresponds to the Agent Group that you want to target as the bootstrap URL for your Kafka client.

In addition, we highly recommend setting the ws_ag client ID feature on your Kafka clients. This is important in dynamic environments like K8s where pods churn frequently and I.P addresses may be quickly cycled between pods running in different agent groups. In that scenario, the Kubernetes service for agent group A may temporarily return the I.P address of an Agent in group B which will result in your client connecting and getting "stuck" in the wrong group.

See this link for more details about how I.P address reuse can cause problems for WarpStream clusters deployed in Kubernetes.

To avoid this issue, configure the name of the agent group you want to target in your client ID. For example, if your existing client ID is: foo, or foo,ws_az=us-east-1a and you want to target an agent group called bar then you should change your client ID to foo,ws_ag=bar or foo,ws_az=us-east-1a,ws_ag=bar respectively. This way, even if K8s service discovery returns a stale I.P address, the Agent that the client ends up connected to will know which agent group the client intended to connect to and be able to re-route it there.

Non-Kubernetes

Most non-Kubernetes deployments use WarpStream's hosted convenience bootstrap URL for service discovery. These URLs are visible in the WarpStream UI under the "Connect" tab in the cluster view and generally look something like this:

api-XXXX-XXXX-XXXX-XXXX-XXXX.kafka.discoveryv2.prod-z.us-east-1.warpstream.com:9092 This bootstrap URL is not group-aware by default and therefore may return Agent I.P addresses for any agent group. To target a specific agent group, modify the bootstrap URL like this:

api-XXXX-XXXX-XXXX-XXXX-XXXX.group$GROUP_NAME.kafka.discoveryv2.prod-z.us-east-1.warpstream.com:9092.

For example, if the agent group name was: "test-group-foo", then the bootstrap URL would become:

api-XXXX-XXXX-XXXX-XXXX-XXXX.grouptest-group-foo.kafka.discoveryv2.prod-z.us-east-1.warpstream.com:9092