kube-metrics-adapter/pkg/collector/hostname_collector.go

package collector

import (
	"fmt"
	"regexp"
	"strings"
	"time"

	autoscalingv2 "k8s.io/api/autoscaling/v2beta2"
)

const (
	HostnameMetricType = "hostname-rps"
	HostnameRPSQuery   = `scalar(sum(rate(%s{host=~"%s"}[1m])))`
)

type HostnameCollectorPlugin struct {
	metricName string
	promPlugin CollectorPlugin
}

type HostnameCollector struct {
	interval      time.Duration
	promCollector Collector
}

func NewHostnameCollectorPlugin(
	promPlugin CollectorPlugin,
	metricName string,
) (*HostnameCollectorPlugin, error) {
	if metricName == "" {
		return nil, fmt.Errorf("failed to initialize hostname collector plugin, metric name was not defined")
	}

	return &HostnameCollectorPlugin{
		metricName: metricName,
		promPlugin: promPlugin,
	}, nil
}

// NewCollector initializes a new skipper collector from the specified HPA.
func (p *HostnameCollectorPlugin) NewCollector(
	hpa *autoscalingv2.HorizontalPodAutoscaler,
	config *MetricConfig,
	interval time.Duration,
) (Collector, error) {
	if config == nil {
		return nil, fmt.Errorf("Metric config not present, it is not possible to initialize the collector.")
	}
	// Need to copy config and add a promQL query in order to get
	// RPS data from a specific hostname from prometheus. The idea
	// of the copy is to not modify the original config struct.
	confCopy := *config
	hostnames := config.Config["hostname"]

	if ok, err := regexp.MatchString("^[a-zA-Z0-9.,-]+$", hostnames); !ok || err != nil {
		return nil, fmt.Errorf(
			"hostname is not specified or invalid format, unable to create collector",
		)
	}

	confCopy.Config = map[string]string{
		"query": fmt.Sprintf(
			HostnameRPSQuery,
			p.metricName,
			strings.Replace(strings.Replace(hostnames, ",", "|", -1), ".", "_", -1),
		),
	}

	c, err := p.promPlugin.NewCollector(hpa, &confCopy, interval)
	if err != nil {
		return nil, err
	}

	return &HostnameCollector{
		interval:      interval,
		promCollector: c,
	}, nil
}

// GetMetrics gets hostname metrics from Prometheus
func (c *HostnameCollector) GetMetrics() ([]CollectedMetric, error) {
	v, err := c.promCollector.GetMetrics()
	if err != nil {
		return nil, err
	}

	if len(v) != 1 {
		return nil, fmt.Errorf("expected to only get one metric value, got %d", len(v))
	}
	return v, nil
}

// Interval returns the interval at which the collector should run.
func (c *HostnameCollector) Interval() time.Duration {
	return c.interval
}