forked from kedacore/keda
/
prometheus_scaler.go
188 lines (157 loc) · 4.69 KB
/
prometheus_scaler.go
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package scalers
import (
"context"
"encoding/json"
"fmt"
"io/ioutil"
"net/http"
url_pkg "net/url"
"strconv"
"time"
v2beta2 "k8s.io/api/autoscaling/v2beta2"
"k8s.io/apimachinery/pkg/api/resource"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/apimachinery/pkg/labels"
"k8s.io/metrics/pkg/apis/external_metrics"
logf "sigs.k8s.io/controller-runtime/pkg/log"
kedautil "github.com/kedacore/keda/pkg/util"
)
const (
promServerAddress = "serverAddress"
promMetricName = "metricName"
promQuery = "query"
promThreshold = "threshold"
)
type prometheusScaler struct {
metadata *prometheusMetadata
}
type prometheusMetadata struct {
serverAddress string
metricName string
query string
threshold int
}
type promQueryResult struct {
Status string `json:"status"`
Data struct {
ResultType string `json:"resultType"`
Result []struct {
Metric struct {
} `json:"metric"`
Value []interface{} `json:"value"`
} `json:"result"`
} `json:"data"`
}
var prometheusLog = logf.Log.WithName("prometheus_scaler")
// NewPrometheusScaler creates a new prometheusScaler
func NewPrometheusScaler(resolvedEnv, metadata map[string]string) (Scaler, error) {
meta, err := parsePrometheusMetadata(metadata, resolvedEnv)
if err != nil {
return nil, fmt.Errorf("error parsing prometheus metadata: %s", err)
}
return &prometheusScaler{
metadata: meta,
}, nil
}
func parsePrometheusMetadata(metadata, resolvedEnv map[string]string) (*prometheusMetadata, error) {
meta := prometheusMetadata{}
if val, ok := metadata[promServerAddress]; ok && val != "" {
meta.serverAddress = val
} else {
return nil, fmt.Errorf("no %s given", promServerAddress)
}
if val, ok := metadata[promQuery]; ok && val != "" {
meta.query = val
} else {
return nil, fmt.Errorf("no %s given", promQuery)
}
if val, ok := metadata[promMetricName]; ok && val != "" {
meta.metricName = val
} else {
return nil, fmt.Errorf("no %s given", promMetricName)
}
if val, ok := metadata[promThreshold]; ok && val != "" {
t, err := strconv.Atoi(val)
if err != nil {
return nil, fmt.Errorf("error parsing %s: %s", promThreshold, err)
}
meta.threshold = t
}
return &meta, nil
}
func (s *prometheusScaler) IsActive(ctx context.Context) (bool, error) {
val, err := s.ExecutePromQuery()
if err != nil {
prometheusLog.Error(err, "error executing prometheus query")
return false, err
}
return val > 0, nil
}
func (s *prometheusScaler) Close() error {
return nil
}
func (s *prometheusScaler) GetMetricSpecForScaling() []v2beta2.MetricSpec {
targetMetricValue := resource.NewQuantity(int64(s.metadata.threshold), resource.DecimalSI)
externalMetric := &v2beta2.ExternalMetricSource{
Metric: v2beta2.MetricIdentifier{
Name: kedautil.NormalizeString(fmt.Sprintf("%s-%s-%s", "prometheus", s.metadata.serverAddress, s.metadata.metricName)),
},
Target: v2beta2.MetricTarget{
Type: v2beta2.AverageValueMetricType,
AverageValue: targetMetricValue,
},
}
metricSpec := v2beta2.MetricSpec{
External: externalMetric, Type: externalMetricType,
}
return []v2beta2.MetricSpec{metricSpec}
}
func (s *prometheusScaler) ExecutePromQuery() (float64, error) {
t := time.Now().UTC().Format(time.RFC3339)
queryEscaped := url_pkg.QueryEscape(s.metadata.query)
url := fmt.Sprintf("%s/api/v1/query?query=%s&time=%s", s.metadata.serverAddress, queryEscaped, t)
r, err := http.Get(url)
if err != nil {
return -1, err
}
b, err := ioutil.ReadAll(r.Body)
if err != nil {
return -1, err
}
r.Body.Close()
var result promQueryResult
err = json.Unmarshal(b, &result)
if err != nil {
return -1, err
}
var v float64 = -1
// allow for zero element or single element result sets
if len(result.Data.Result) == 0 {
return 0, nil
} else if len(result.Data.Result) > 1 {
return -1, fmt.Errorf("Prometheus query %s returned multiple elements", s.metadata.query)
}
val := result.Data.Result[0].Value[1]
if val != nil {
s := val.(string)
v, err = strconv.ParseFloat(s, 64)
if err != nil {
prometheusLog.Error(err, "Error converting prometheus value", "prometheus_value", s)
return -1, err
}
}
return v, nil
}
func (s *prometheusScaler) GetMetrics(ctx context.Context, metricName string, metricSelector labels.Selector) ([]external_metrics.ExternalMetricValue, error) {
val, err := s.ExecutePromQuery()
if err != nil {
prometheusLog.Error(err, "error executing prometheus query")
return []external_metrics.ExternalMetricValue{}, err
}
metric := external_metrics.ExternalMetricValue{
MetricName: metricName,
Value: *resource.NewQuantity(int64(val), resource.DecimalSI),
Timestamp: metav1.Now(),
}
return append([]external_metrics.ExternalMetricValue{}, metric), nil
}