k8s hpa计算

 

hpa targets计算核心代码

代码位置：github.com/kubernetes/pkg/controller/podautoscaler/metrics/utilization.go

遍历metrics，如果当前podName没有设置request则跳过。

把每个podName对应的metrics的value累加得到metricsTotal, 把每个podName对应的request累加得到requestsTotal。

当前pod资源使用情况：currentUtilization = (metricsTotal * 100 ) / requestsTotal

资源使用率: usageRatio = currentUtilization / 设置扩容时候的百分比， 如80%，则这里为80。

// GetResourceUtilizationRatio takes in a set of metrics, a set of matching requests,
// and a target utilization percentage, and calculates the ratio of
// desired to actual utilization (returning that, the actual utilization, and the raw average value)
func GetResourceUtilizationRatio(metrics PodMetricsInfo, requests map[string]int64, targetUtilization int32) (utilizationRatio float64, currentUtilization int32, rawAverageValue int64, err error) {
	metricsTotal := int64(0)
	requestsTotal := int64(0)
	numEntries := 0

	for podName, metric := range metrics {
		request, hasRequest := requests[podName]
		if !hasRequest {
			// we check for missing requests elsewhere, so assuming missing requests == extraneous metrics
			continue
		}

		metricsTotal += metric.Value
		requestsTotal += request
		numEntries++
	}

	// if the set of requests is completely disjoint from the set of metrics,
	// then we could have an issue where the requests total is zero
	if requestsTotal == 0 {
		return 0, 0, 0, fmt.Errorf("no metrics returned matched known pods")
	}

	currentUtilization = int32((metricsTotal * 100) / requestsTotal)

	return float64(currentUtilization) / float64(targetUtilization), currentUtilization, metricsTotal / int64(numEntries), nil
}