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Chapter 6. Known issues
This section lists the known issues for AMQ Streams 2.1.
6.1. AMQ Streams Cluster Operator on IPv6 clusters
The AMQ Streams Cluster Operator does not start on Internet Protocol version 6 (IPv6) clusters.
Workaround
There are two workarounds for this issue.
Workaround one: Set the KUBERNETES_MASTER environment variable
Display the address of the Kubernetes master node of your OpenShift Container Platform cluster:
oc cluster-info Kubernetes master is running at <master_address> # ...Copy the address of the master node.
List all Operator subscriptions:
oc get subs -n <operator_namespace>Edit the
Subscriptionresource for AMQ Streams:oc edit sub amq-streams -n <operator_namespace>In
spec.config.env, add theKUBERNETES_MASTERenvironment variable, set to the address of the Kubernetes master node. For example:apiVersion: operators.coreos.com/v1alpha1 kind: Subscription metadata: name: amq-streams namespace: OPERATOR-NAMESPACE spec: channel: amq-streams-1.8.x installPlanApproval: Automatic name: amq-streams source: mirror-amq-streams sourceNamespace: openshift-marketplace config: env: - name: KUBERNETES_MASTER value: MASTER-ADDRESS
- Save and exit the editor.
Check that the
Subscriptionwas updated:oc get sub amq-streams -n <operator_namespace>Check that the Cluster Operator
Deploymentwas updated to use the new environment variable:oc get deployment <cluster_operator_deployment_name>
Workaround two: Disable hostname verification
List all Operator subscriptions:
oc get subs -n OPERATOR-NAMESPACEEdit the
Subscriptionresource for AMQ Streams:oc edit sub amq-streams -n <operator_namespace>In
spec.config.env, add theKUBERNETES_DISABLE_HOSTNAME_VERIFICATIONenvironment variable, set totrue. For example:apiVersion: operators.coreos.com/v1alpha1 kind: Subscription metadata: name: amq-streams namespace: OPERATOR-NAMESPACE spec: channel: amq-streams-1.8.x installPlanApproval: Automatic name: amq-streams source: mirror-amq-streams sourceNamespace: openshift-marketplace config: env: - name: KUBERNETES_DISABLE_HOSTNAME_VERIFICATION value: "true"- Save and exit the editor.
Check that the
Subscriptionwas updated:oc get sub amq-streams -n <operator_namespace>Check that the Cluster Operator
Deploymentwas updated to use the new environment variable:oc get deployment <cluster_operator_deployment_name>
6.2. Cruise Control CPU utilization estimation
Cruise Control for AMQ Streams has a known issue that relates to the calculation of CPU utilization estimation. CPU utilization is calculated as a percentage of the defined capacity of a broker pod. The issue occurs when running Kafka brokers across nodes with varying CPU cores. For example, node1 might have 2 CPU cores and node2 might have 4 CPU cores. In this situation, Cruise Control can underestimate and overestimate CPU load of brokers The issue can prevent cluster rebalances when the pod is under heavy load.
Workaround
There are two workarounds for this issue.
Workaround one: Equal CPU requests and limits
You can set CPU requests equal to CPU limits in Kafka.spec.kafka.resources. That way, all CPU resources are reserved upfront and are always available. This configuration allows Cruise Control to properly evaluate the CPU utilization when preparing the rebalance proposals based on CPU goals.
Workaround two: Exclude CPU goals
You can exclude CPU goals from the hard and default goals specified in the Cruise Control configuration.
Example Cruise Control configuration without CPU goals
apiVersion: kafka.strimzi.io/v1beta2
kind: Kafka
metadata:
name: my-cluster
spec:
kafka:
# ...
zookeeper:
# ...
entityOperator:
topicOperator: {}
userOperator: {}
cruiseControl:
brokerCapacity:
inboundNetwork: 10000KB/s
outboundNetwork: 10000KB/s
config:
hard.goals: >
com.linkedin.kafka.cruisecontrol.analyzer.goals.RackAwareGoal,
com.linkedin.kafka.cruisecontrol.analyzer.goals.MinTopicLeadersPerBrokerGoal,
com.linkedin.kafka.cruisecontrol.analyzer.goals.ReplicaCapacityGoal,
com.linkedin.kafka.cruisecontrol.analyzer.goals.DiskCapacityGoal,
com.linkedin.kafka.cruisecontrol.analyzer.goals.NetworkInboundCapacityGoal,
com.linkedin.kafka.cruisecontrol.analyzer.goals.NetworkOutboundCapacityGoal
default.goals: >
com.linkedin.kafka.cruisecontrol.analyzer.goals.RackAwareGoal,
com.linkedin.kafka.cruisecontrol.analyzer.goals.MinTopicLeadersPerBrokerGoal,
com.linkedin.kafka.cruisecontrol.analyzer.goals.ReplicaCapacityGoal,
com.linkedin.kafka.cruisecontrol.analyzer.goals.DiskCapacityGoal,
com.linkedin.kafka.cruisecontrol.analyzer.goals.NetworkInboundCapacityGoal,
com.linkedin.kafka.cruisecontrol.analyzer.goals.NetworkOutboundCapacityGoal,
com.linkedin.kafka.cruisecontrol.analyzer.goals.ReplicaDistributionGoal,
com.linkedin.kafka.cruisecontrol.analyzer.goals.PotentialNwOutGoal,
com.linkedin.kafka.cruisecontrol.analyzer.goals.DiskUsageDistributionGoal,
com.linkedin.kafka.cruisecontrol.analyzer.goals.NetworkInboundUsageDistributionGoal,
com.linkedin.kafka.cruisecontrol.analyzer.goals.NetworkOutboundUsageDistributionGoal,
com.linkedin.kafka.cruisecontrol.analyzer.goals.TopicReplicaDistributionGoal,
com.linkedin.kafka.cruisecontrol.analyzer.goals.LeaderReplicaDistributionGoal,
com.linkedin.kafka.cruisecontrol.analyzer.goals.LeaderBytesInDistributionGoal
For more information, see Insufficient CPU capacity.
