Configuration
There are two main configuration mechanisms that can be used to configure Karpenter: Environment Variables / CLI parameters to the controller and webhook binaries and the karpenter-global-settings config-map.
Environment Variables / CLI Flags
| Environment Variable | CLI Flag | Description |
|---|---|---|
| AWS_DEFAULT_INSTANCE_PROFILE | --aws-default-instance-profile | The default instance profile to use when provisioning nodes in AWS |
| AWS_ENABLE_POD_ENI | --aws-enable-pod-eni | If true then instances that support pod ENI will report a vpc.amazonaws.com/pod-eni resource (default = false) |
| AWS_ENI_LIMITED_POD_DENSITY | --aws-eni-limited-pod-density | Indicates whether new nodes should use ENI-based pod density. DEPRECATED: Use .spec.kubeletConfiguration.maxPods to set pod density on a per-provisioner basis (default = true) |
| AWS_ISOLATED_VPC | --aws-isolated-vpc | If true then assume we can’t reach AWS services which don’t have a VPC endpoint (default = false) |
| AWS_NODE_NAME_CONVENTION | --aws-node-name-convention | The node naming convention used by the AWS cloud provider. DEPRECATION WARNING: this field may be deprecated at any time (default = ip-name) |
| CLUSTER_ENDPOINT | --cluster-endpoint | The external kubernetes cluster endpoint for new nodes to connect with |
| CLUSTER_NAME | --cluster-name | The kubernetes cluster name for resource discovery |
| ENABLE_PROFILING | --enable-profiling | Enable the profiling on the metric endpoint (default = false) |
| HEALTH_PROBE_PORT | --health-probe-port | The port the health probe endpoint binds to for reporting controller health (default = 8081) |
| KUBE_CLIENT_BURST | --kube-client-burst | The maximum allowed burst of queries to the kube-apiserver (default = 300) |
| KUBE_CLIENT_QPS | --kube-client-qps | The smoothed rate of qps to kube-apiserver (default = 200) |
| METRICS_PORT | --metrics-port | The port the metric endpoint binds to for operating metrics about the controller itself (default = 8080) |
| VM_MEMORY_OVERHEAD | --vm-memory-overhead | The VM memory overhead as a percent that will be subtracted from the total memory for all instance types (default = 0.075) |
ConfigMap
Karpenter installs a default configuration via its Helm chart that should work for most. Additional configuration can be performed by editing the karpenter-global-settings configmap within the namespace that Karpenter was installed in.
apiVersion: v1
kind: ConfigMap
data:
# The maximum length of a batch window. The longer this is, the more pods we can consider for provisioning at one
# time which usually results in fewer but larger nodes.
batchMaxDuration: 10s
# The maximum amount of time with no new ending pods that if exceeded ends the current batching window. If pods arrive
# faster than this time, the batching window will be extended up to the maxDuration. If they arrive slower, the pods
# will be batched separately.
batchIdleDuration: 1s
Batching Parameters
The batching parameters control how Karpenter batches an incoming stream of pending pods. Reducing these values may trade off a slightly faster time from pending pod to node launch, in exchange for launching smaller nodes. Increasing the values can do the inverse. Karpenter provides reasonable defaults for these values, but if you have specific knowledge about your workloads you can tweak these parameters to match the expected rate of incoming pods.
For a standard deployment scale-up, the pods arrive at the QPS setting of the kube-controller-manager, and the default values are typically fine. These settings are intended for use cases where other systems may create large numbers of pods over a period of many seconds or minutes and there is a desire to batch them together.
batchIdleDuration
The batchIdleDuration is the period of time that a new pending pod extends the current batching window. This can be increased to handle scenarios where pods arrive slower than one second part, but it would be preferable if they were batched together onto a single larger node.
This value is expressed as a string value like 10s, 1m or 2h45m. The valid time units are ns, us (or µs), ms, s, m, h.
batchMaxDuration
The batchMaxDuration is the maximum period of time a batching window can be extended to. Increasing this value will allow the maximum batch window size to increase to collect more pending pods into a single batch at the expense of a longer delay from when the first pending pod was created.
This value is expressed as a string value like 10s, 1m or 2h45m. The valid time units are ns, us (or µs), ms, s, m, h.