CRI Pod & Container Metrics

The kubelet collects pod and container metrics via cAdvisor. As a beta feature, Kubernetes lets you configure the collection of pod and container metrics via the Container Runtime Interface (CRI). You must enable the PodAndContainerStatsFromCRI feature gate and use a compatible CRI implementation (containerd >= 2.2, CRI-O >= 1.31.0) to use the CRI based collection mechanism.

CRI Pod & Container Metrics

With PodAndContainerStatsFromCRI enabled, the kubelet polls the underlying container runtime for pod and container stats instead of inspecting the host system directly using cAdvisor. The benefits of relying on the container runtime for this information as opposed to direct collection with cAdvisor include:

• Potential improved performance if the container runtime already collects this information during normal operations. In this case, the data can be re-used instead of being aggregated again by the kubelet.

• It further decouples the kubelet and the container runtime allowing collection of metrics for container runtimes that don't run processes directly on the host with kubelet where they are observable by cAdvisor (for example: container runtimes that use virtualization).

Affected endpoints

When the feature gate is enabled, the kubelet queries the CRI runtime for pod and container level data instead of cAdvisor. Node-level and image filesystem stats continue to be collected from cAdvisor. The following endpoints are affected:

Summary API (/stats/summary)

The kubelet fetches pod and container stats from the CRI runtime instead of cAdvisor for the Summary API. This includes CPU, memory, network, and process stats for pods and containers.

/metrics/cadvisor

The kubelet queries the CRI runtime for pod and container metrics via the ListPodSandboxMetrics RPC and serves them on the /metrics/cadvisor endpoint. This replaces the cAdvisor-based collection at the pod and container level while preserving the same endpoint path and metric names. Node and machine-level metrics on this endpoint continue to be served by cAdvisor.

Identifying the active metrics provider

The kubelet exposes a kubelet_metrics_provider metric with a provider label set to either cri or cadvisor. You can use this metric to verify which source is actively providing pod and container stats on a given node.

Requirements

To use CRI-based metrics collection, you need:

• containerd version 2.2 or later, or CRI-O version 1.31.0 or later
• The PodAndContainerStatsFromCRI feature gate enabled on the kubelet

Fallback behavior

If the CRI runtime does not report the expected metrics, the kubelet falls back to using cAdvisor for pod and container stats collection, even when the feature gate is enabled. You can disable the feature gate with a kubelet restart to fully revert to cAdvisor-based collection.