Collecting metrics with Kubernetes
Kubernetes has a Metrics API. It supports node and pod metrics out of the box. You can also define your own custom metrics.
A metric contains a timestamp, a usage field, and the time range in which the metric was collected (many metrics are accumulated over a time period). Here is the API definition for node metrics:
type NodeMetrics struct {
metav1.TypeMeta
metav1.ObjectMeta
Timestamp metav1.Time
Window metav1.Duration
Usage corev1.ResourceList
}
// NodeMetricsList is a list of NodeMetrics.
type NodeMetricsList struct {
metav1.TypeMeta
// Standard list metadata.
// More info: https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#types-kinds
metav1.ListMeta
// List of node metrics.
Items []NodeMetrics
}
The usage field type is ResourceList, but it’s actually a map of a resource name to a quantity:
// ResourceList is a set of (resource name, quantity...