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metrics_api_scaler.go
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metrics_api_scaler.go
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package scalers
import (
"context"
"encoding/xml"
"errors"
"fmt"
"io"
"net/http"
neturl "net/url"
"strconv"
"strings"
"github.com/go-logr/logr"
"github.com/prometheus/common/expfmt"
"github.com/prometheus/prometheus/promql/parser"
"github.com/tidwall/gjson"
"gopkg.in/yaml.v3"
v2 "k8s.io/api/autoscaling/v2"
"k8s.io/apimachinery/pkg/api/resource"
"k8s.io/metrics/pkg/apis/external_metrics"
"github.com/kedacore/keda/v2/pkg/scalers/authentication"
"github.com/kedacore/keda/v2/pkg/scalers/scalersconfig"
kedautil "github.com/kedacore/keda/v2/pkg/util"
)
type metricsAPIScaler struct {
metricType v2.MetricTargetType
metadata *metricsAPIScalerMetadata
httpClient *http.Client
logger logr.Logger
}
type metricsAPIScalerMetadata struct {
targetValue float64
activationTargetValue float64
url string
format APIFormat
valueLocation string
unsafeSsl bool
// apiKeyAuth
enableAPIKeyAuth bool
method string // way of providing auth key, either "header" (default) or "query"
// keyParamName is either header key or query param used for passing apikey
// default header is "X-API-KEY", defaul query param is "api_key"
keyParamName string
apiKey string
// base auth
enableBaseAuth bool
username string
password string // +optional
// client certification
enableTLS bool
cert string
key string
ca string
// bearer
enableBearerAuth bool
bearerToken string
triggerIndex int
}
const (
methodValueQuery = "query"
valueLocationWrongErrorMsg = "valueLocation must point to value of type number or a string representing a Quantity got: '%s'"
)
type APIFormat string
// Options for APIFormat:
const (
PrometheusFormat APIFormat = "prometheus"
JSONFormat APIFormat = "json"
XMLFormat APIFormat = "xml"
YAMLFormat APIFormat = "yaml"
)
var (
supportedFormats = []APIFormat{
PrometheusFormat,
JSONFormat,
XMLFormat,
YAMLFormat,
}
)
// NewMetricsAPIScaler creates a new HTTP scaler
func NewMetricsAPIScaler(config *scalersconfig.ScalerConfig) (Scaler, error) {
metricType, err := GetMetricTargetType(config)
if err != nil {
return nil, fmt.Errorf("error getting scaler metric type: %w", err)
}
meta, err := parseMetricsAPIMetadata(config)
if err != nil {
return nil, fmt.Errorf("error parsing metric API metadata: %w", err)
}
httpClient := kedautil.CreateHTTPClient(config.GlobalHTTPTimeout, meta.unsafeSsl)
if meta.enableTLS || len(meta.ca) > 0 {
config, err := kedautil.NewTLSConfig(meta.cert, meta.key, meta.ca, meta.unsafeSsl)
if err != nil {
return nil, err
}
httpClient.Transport = kedautil.CreateHTTPTransportWithTLSConfig(config)
}
return &metricsAPIScaler{
metricType: metricType,
metadata: meta,
httpClient: httpClient,
logger: InitializeLogger(config, "metrics_api_scaler"),
}, nil
}
func parseMetricsAPIMetadata(config *scalersconfig.ScalerConfig) (*metricsAPIScalerMetadata, error) {
meta := metricsAPIScalerMetadata{}
meta.triggerIndex = config.TriggerIndex
meta.unsafeSsl = false
if val, ok := config.TriggerMetadata["unsafeSsl"]; ok {
unsafeSsl, err := strconv.ParseBool(val)
if err != nil {
return nil, fmt.Errorf("error parsing unsafeSsl: %w", err)
}
meta.unsafeSsl = unsafeSsl
}
if val, ok := config.TriggerMetadata["targetValue"]; ok {
targetValue, err := strconv.ParseFloat(val, 64)
if err != nil {
return nil, fmt.Errorf("targetValue parsing error %w", err)
}
meta.targetValue = targetValue
} else {
if config.AsMetricSource {
meta.targetValue = 0
} else {
return nil, fmt.Errorf("no targetValue given in metadata")
}
}
meta.activationTargetValue = 0
if val, ok := config.TriggerMetadata["activationTargetValue"]; ok {
activationTargetValue, err := strconv.ParseFloat(val, 64)
if err != nil {
return nil, fmt.Errorf("targetValue parsing error %w", err)
}
meta.activationTargetValue = activationTargetValue
}
if val, ok := config.TriggerMetadata["url"]; ok {
meta.url = val
} else {
return nil, fmt.Errorf("no url given in metadata")
}
if val, ok := config.TriggerMetadata["format"]; ok {
meta.format = APIFormat(strings.TrimSpace(val))
if !kedautil.Contains(supportedFormats, meta.format) {
return nil, fmt.Errorf("format %s not supported", meta.format)
}
} else {
// default format is JSON for backward compatibility
meta.format = JSONFormat
}
if val, ok := config.TriggerMetadata["valueLocation"]; ok {
meta.valueLocation = val
} else {
return nil, fmt.Errorf("no valueLocation given in metadata")
}
authMode, ok := config.TriggerMetadata["authMode"]
// no authMode specified
if !ok {
return &meta, nil
}
authType := authentication.Type(strings.TrimSpace(authMode))
switch authType {
case authentication.APIKeyAuthType:
if len(config.AuthParams["apiKey"]) == 0 {
return nil, errors.New("no apikey provided")
}
meta.apiKey = config.AuthParams["apiKey"]
// default behaviour is header. only change if query param requested
meta.method = "header"
meta.enableAPIKeyAuth = true
if config.TriggerMetadata["method"] == methodValueQuery {
meta.method = methodValueQuery
}
if len(config.TriggerMetadata["keyParamName"]) > 0 {
meta.keyParamName = config.TriggerMetadata["keyParamName"]
}
case authentication.BasicAuthType:
if len(config.AuthParams["username"]) == 0 {
return nil, errors.New("no username given")
}
meta.username = config.AuthParams["username"]
// password is optional. For convenience, many application implements basic auth with
// username as apikey and password as empty
meta.password = config.AuthParams["password"]
meta.enableBaseAuth = true
case authentication.TLSAuthType:
if len(config.AuthParams["ca"]) == 0 {
return nil, errors.New("no ca given")
}
if len(config.AuthParams["cert"]) == 0 {
return nil, errors.New("no cert given")
}
meta.cert = config.AuthParams["cert"]
if len(config.AuthParams["key"]) == 0 {
return nil, errors.New("no key given")
}
meta.key = config.AuthParams["key"]
meta.enableTLS = true
case authentication.BearerAuthType:
if len(config.AuthParams["token"]) == 0 {
return nil, errors.New("no token provided")
}
meta.bearerToken = config.AuthParams["token"]
meta.enableBearerAuth = true
default:
return nil, fmt.Errorf("err incorrect value for authMode is given: %s", authMode)
}
if len(config.AuthParams["ca"]) > 0 {
meta.ca = config.AuthParams["ca"]
}
return &meta, nil
}
// GetValueFromResponse uses provided valueLocation to access the numeric value in provided body using the format specified.
func GetValueFromResponse(body []byte, valueLocation string, format APIFormat) (float64, error) {
switch format {
case PrometheusFormat:
return getValueFromPrometheusResponse(body, valueLocation)
case JSONFormat:
return getValueFromJSONResponse(body, valueLocation)
case XMLFormat:
return getValueFromXMLResponse(body, valueLocation)
case YAMLFormat:
return getValueFromYAMLResponse(body, valueLocation)
}
return 0, fmt.Errorf("format %s not supported", format)
}
// getValueFromPrometheusResponse uses provided valueLocation to access the numeric value in provided body
func getValueFromPrometheusResponse(body []byte, valueLocation string) (float64, error) {
matchers, err := parser.ParseMetricSelector(valueLocation)
if err != nil {
return 0, err
}
metricName := ""
for _, v := range matchers {
if v.Name == "__name__" {
metricName = v.Value
}
}
// Ensure EOL
reader := strings.NewReader(strings.ReplaceAll(string(body), "\r\n", "\n"))
familiesParser := expfmt.TextParser{}
families, err := familiesParser.TextToMetricFamilies(reader)
if err != nil {
return 0, err
}
family, ok := families[metricName]
if !ok {
return 0, fmt.Errorf("metric '%s' not found", metricName)
}
metrics := family.GetMetric()
for _, metric := range metrics {
labels := metric.GetLabel()
match := true
for _, matcher := range matchers {
matcherFound := false
if matcher == nil {
continue
}
// The name has been already validated,
// so we can skip it and check the other labels
if matcher.Name == "__name__" {
continue
}
for _, label := range labels {
if *label.Name == matcher.Name &&
*label.Value == matcher.Value {
matcherFound = true
}
}
if !matcherFound {
match = false
}
}
if match {
untyped := metric.GetUntyped()
if untyped != nil && untyped.Value != nil {
return *untyped.Value, nil
}
counter := metric.GetCounter()
if counter != nil && counter.Value != nil {
return *counter.Value, nil
}
gauge := metric.GetGauge()
if gauge != nil && gauge.Value != nil {
return *gauge.Value, nil
}
}
}
return 0, fmt.Errorf("value %s not found", valueLocation)
}
// getValueFromJSONResponse uses provided valueLocation to access the numeric value in provided body using GJSON
func getValueFromJSONResponse(body []byte, valueLocation string) (float64, error) {
r := gjson.GetBytes(body, valueLocation)
if r.Type == gjson.String {
v, err := resource.ParseQuantity(r.String())
if err != nil {
return 0, fmt.Errorf(valueLocationWrongErrorMsg, r.String())
}
return v.AsApproximateFloat64(), nil
}
if r.Type != gjson.Number {
return 0, fmt.Errorf(valueLocationWrongErrorMsg, r.Type.String())
}
return r.Num, nil
}
// getValueFromXMLResponse uses provided valueLocation to access the numeric value in provided body
func getValueFromXMLResponse(body []byte, valueLocation string) (float64, error) {
var xmlMap map[string]interface{}
err := xml.Unmarshal(body, &xmlMap)
if err != nil {
return 0, err
}
path, err := kedautil.GetValueByPath(xmlMap, valueLocation)
if err != nil {
return 0, err
}
switch v := path.(type) {
case int:
return float64(v), nil
case int64:
return float64(v), nil
case float64:
return v, nil
case string:
r, err := resource.ParseQuantity(v)
if err != nil {
return 0, fmt.Errorf(valueLocationWrongErrorMsg, v)
}
return r.AsApproximateFloat64(), nil
default:
return 0, fmt.Errorf(valueLocationWrongErrorMsg, v)
}
}
// getValueFromYAMLResponse uses provided valueLocation to access the numeric value in provided body
// using generic ketautil.GetValueByPath
func getValueFromYAMLResponse(body []byte, valueLocation string) (float64, error) {
var yamlMap map[string]interface{}
err := yaml.Unmarshal(body, &yamlMap)
if err != nil {
return 0, err
}
path, err := kedautil.GetValueByPath(yamlMap, valueLocation)
if err != nil {
return 0, err
}
switch v := path.(type) {
case int:
return float64(v), nil
case int64:
return float64(v), nil
case float64:
return v, nil
case string:
r, err := resource.ParseQuantity(v)
if err != nil {
return 0, fmt.Errorf(valueLocationWrongErrorMsg, v)
}
return r.AsApproximateFloat64(), nil
default:
return 0, fmt.Errorf(valueLocationWrongErrorMsg, v)
}
}
func (s *metricsAPIScaler) getMetricValue(ctx context.Context) (float64, error) {
request, err := getMetricAPIServerRequest(ctx, s.metadata)
if err != nil {
return 0, err
}
r, err := s.httpClient.Do(request)
if err != nil {
return 0, err
}
defer r.Body.Close()
if r.StatusCode != http.StatusOK {
msg := fmt.Sprintf("%s: api returned %d", r.Request.URL.Path, r.StatusCode)
return 0, errors.New(msg)
}
b, err := io.ReadAll(r.Body)
if err != nil {
return 0, err
}
v, err := GetValueFromResponse(b, s.metadata.valueLocation, s.metadata.format)
if err != nil {
return 0, err
}
return v, nil
}
// Close does nothing in case of metricsAPIScaler
func (s *metricsAPIScaler) Close(context.Context) error {
if s.httpClient != nil {
s.httpClient.CloseIdleConnections()
}
return nil
}
// GetMetricSpecForScaling returns the MetricSpec for the Horizontal Pod Autoscaler
func (s *metricsAPIScaler) GetMetricSpecForScaling(context.Context) []v2.MetricSpec {
externalMetric := &v2.ExternalMetricSource{
Metric: v2.MetricIdentifier{
Name: GenerateMetricNameWithIndex(s.metadata.triggerIndex, kedautil.NormalizeString(fmt.Sprintf("metric-api-%s", s.metadata.valueLocation))),
},
Target: GetMetricTargetMili(s.metricType, s.metadata.targetValue),
}
metricSpec := v2.MetricSpec{
External: externalMetric, Type: externalMetricType,
}
return []v2.MetricSpec{metricSpec}
}
// GetMetricsAndActivity returns value for a supported metric and an error if there is a problem getting the metric
func (s *metricsAPIScaler) GetMetricsAndActivity(ctx context.Context, metricName string) ([]external_metrics.ExternalMetricValue, bool, error) {
val, err := s.getMetricValue(ctx)
if err != nil {
return []external_metrics.ExternalMetricValue{}, false, fmt.Errorf("error requesting metrics endpoint: %w", err)
}
metric := GenerateMetricInMili(metricName, val)
return []external_metrics.ExternalMetricValue{metric}, val > s.metadata.activationTargetValue, nil
}
func getMetricAPIServerRequest(ctx context.Context, meta *metricsAPIScalerMetadata) (*http.Request, error) {
var req *http.Request
var err error
switch {
case meta.enableAPIKeyAuth:
if meta.method == methodValueQuery {
url, _ := neturl.Parse(meta.url)
queryString := url.Query()
if len(meta.keyParamName) == 0 {
queryString.Set("api_key", meta.apiKey)
} else {
queryString.Set(meta.keyParamName, meta.apiKey)
}
url.RawQuery = queryString.Encode()
req, err = http.NewRequestWithContext(ctx, "GET", url.String(), nil)
if err != nil {
return nil, err
}
} else {
// default behaviour is to use header method
req, err = http.NewRequestWithContext(ctx, "GET", meta.url, nil)
if err != nil {
return nil, err
}
if len(meta.keyParamName) == 0 {
req.Header.Add("X-API-KEY", meta.apiKey)
} else {
req.Header.Add(meta.keyParamName, meta.apiKey)
}
}
case meta.enableBaseAuth:
req, err = http.NewRequestWithContext(ctx, "GET", meta.url, nil)
if err != nil {
return nil, err
}
req.SetBasicAuth(meta.username, meta.password)
case meta.enableBearerAuth:
req, err = http.NewRequestWithContext(ctx, "GET", meta.url, nil)
if err != nil {
return nil, err
}
req.Header.Add("Authorization", fmt.Sprintf("Bearer %s", meta.bearerToken))
default:
req, err = http.NewRequestWithContext(ctx, "GET", meta.url, nil)
if err != nil {
return nil, err
}
}
return req, nil
}