Kubecost

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Network Traffic Cost Allocation

This document summarizes Kubecost network cost allocation, how to enable it, and what it provides.

When this feature is enabled, Kubecost gathers network traffic metrics in combination with provider-specific network costs to provide insight on network data sources as well as the aggregate costs of transfers.

Enabling Network Costs

To enable this feature, set the following parameter in values.yaml during Helm installation:

 networkCosts.enabled=true

You can view a list of common Kubecost chart config options here.

Note: network cost, disabled by default, run as a privileged pod to access the relevant networking kernel module on the host.

Kubernetes Network Traffic Metrics

The primary source of network metrics come from a daemonset pod hosted on each of the nodes in a cluster. Each daemonset pod uses hostNetwork: true such that it can leverage an underlying kernel module to capture network data. Network traffic data is gathered and the destination of any outbound networking is labeled as:

  • Internet Egress: Network target destination was not identified within the cluster.
  • Cross Region Egress: Network target destination was identified, but not in the same provider region.
  • Cross Zone Egress: Network target destination was identified, and was part of the same region but not the same zone.

These classifications are important because they correlate with network costing models for most cloud providers. To see more detail on these metric classifications, you can view pod logs with the following command:

kubectl logs kubecost-network-costs-<pod-identifier> -n kubecost

This will show you top source and destination IP addresses and bytes transferred on the node where this pod is running.

Whitelisting internal addresses

For addresses that are outside of your cluster but inside your VPC, Kubecost supports IP or CIDR block whitelisting. This feature can be configured in your values.yaml under networkCosts.config. Any address within the whitelist will be considered in region and in zone traffic.

Troubleshooting

To verify this feature is functioning properly, you can complete the following steps:

  1. Confirm the kubecost-network-costs pods are Running. If these pods are not in a Running state, kubectl describe them and/or view their logs for errors.
  2. Ensure kubecost-networking target is Up in your Prometheus Targets list. View any visible errors if this target is not Up. You can further verify data is being scrapped by the presence of the kubecost_pod_network_egress_bytes_total metric in Prometheus.
  3. Verify Network Costs are available in your Kubecost Allocation view. View your browser’s Developer Console on this page for any access/permissions errors if costs are not shown.

Common issues:

  • Failed to locate network pods – Error message displayed when the Kubecost app is unable to locate the network pods, which we search for by a label that includes our release name. In particular, we depend on the label app=<release-name>-network-costs to locate the pods. If the app has a blank release name this issue may happen.

  • Resource usage is a function of unique src and dest IP/port combinations. Most deployments use a small fraction of a CPU and it is also ok to have this pod CPU throttled moderately.

Feature Limitations

  • Today this feature is supported on Unix-based images with conntrack
  • Actively tested against GCP, AWS, and Azure to date
  • Daemonsets have shared IP addresses on certain clusters