Add ActiveMQ scaler

CHANGELOG.md

@@ -23,6 +23,8 @@
 
 ### New
 
+- Add ActiveMQ Scaler ([#2305](https://github.com/kedacore/keda/pull/2305))
+
 - TODO ([#XXX](https://github.com/kedacore/keda/pull/XXX))
 
 ### Improvements

pkg/scalers/activemq_scaler.go

@@ -0,0 +1,278 @@
+package scalers
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"net/http"
+	"net/url"
+	"strconv"
+	"strings"
+	"text/template"
+
+	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/v2/pkg/util"
+)
+
+type activeMQScaler struct {
+	metadata   *activeMQMetadata
+	httpClient *http.Client
+}
+
+type activeMQMetadata struct {
+	managementEndpoint string
+	destinationName    string
+	brokerName         string
+	username           string
+	password           string
+	restAPITemplate    string
+	targetQueueSize    int
+	metricName         string
+	scalerIndex        int
+}
+
+type activeMQMonitoring struct {
+	MsgCount  int   `json:"value"`
+	Status    int   `json:"status"`
+	Timestamp int64 `json:"timestamp"`
+}
+
+const (
+	defaultTargetQueueSize         = 10
+	defaultActiveMQRestAPITemplate = "http://{{.ManagementEndpoint}}/api/jolokia/read/org.apache.activemq:type=Broker,brokerName={{.BrokerName}},destinationType=Queue,destinationName={{.DestinationName}}/QueueSize"
+)
+
+var activeMQLog = logf.Log.WithName("activeMQ_scaler")
+
+// NewActiveMQScaler creates a new activeMQ Scaler
+func NewActiveMQScaler(config *ScalerConfig) (Scaler, error) {
+	meta, err := parseActiveMQMetadata(config)
+	if err != nil {
+		return nil, fmt.Errorf("error parsing ActiveMQ metadata: %s", err)
+	}
+	httpClient := kedautil.CreateHTTPClient(config.GlobalHTTPTimeout, false)
+
+	return &activeMQScaler{
+		metadata:   meta,
+		httpClient: httpClient,
+	}, nil
+}
+
+func parseActiveMQMetadata(config *ScalerConfig) (*activeMQMetadata, error) {
+	meta := activeMQMetadata{}
+
+	if val, ok := config.TriggerMetadata["restAPITemplate"]; ok && val != "" {
+		meta.restAPITemplate = config.TriggerMetadata["restAPITemplate"]
+		var err error
+		if meta, err = getRestAPIParameters(meta); err != nil {
+			return nil, fmt.Errorf("can't parse restAPITemplate : %s ", err)
+		}
+	} else {
+		meta.restAPITemplate = defaultActiveMQRestAPITemplate
+		if config.TriggerMetadata["managementEndpoint"] == "" {
+			return nil, errors.New("no management endpoint given")
+		}
+		meta.managementEndpoint = config.TriggerMetadata["managementEndpoint"]
+
+		if config.TriggerMetadata["destinationName"] == "" {
+			return nil, errors.New("no destination name given")
+		}
+		meta.destinationName = config.TriggerMetadata["destinationName"]
+
+		if config.TriggerMetadata["brokerName"] == "" {
+			return nil, errors.New("no broker name given")
+		}
+		meta.brokerName = config.TriggerMetadata["brokerName"]
+	}
+
+	if val, ok := config.TriggerMetadata["targetQueueSize"]; ok {
+		queueSize, err := strconv.Atoi(val)
+		if err != nil {
+			return nil, fmt.Errorf("invalid targetQueueSize - must be an integer")
+		}
+
+		meta.targetQueueSize = queueSize
+	} else {
+		meta.targetQueueSize = defaultTargetQueueSize
+	}
+
+	if val, ok := config.AuthParams["username"]; ok && val != "" {
+		meta.username = val
+	} else if val, ok := config.TriggerMetadata["username"]; ok && val != "" {
+		username := val
+
+		if val, ok := config.ResolvedEnv[username]; ok && val != "" {
+			meta.username = val
+		} else {
+			meta.username = username
+		}
+	}
+
+	if meta.username == "" {
+		return nil, fmt.Errorf("username cannot be empty")
+	}
+
+	if val, ok := config.AuthParams["password"]; ok && val != "" {
+		meta.password = val
+	} else if val, ok := config.TriggerMetadata["password"]; ok && val != "" {
+		password := val
+
+		if val, ok := config.ResolvedEnv[password]; ok && val != "" {
+			meta.password = val
+		} else {
+			meta.password = password
+		}
+	}
+
+	if meta.password == "" {
+		return nil, fmt.Errorf("password cannot be empty")
+	}
+
+	meta.metricName = GenerateMetricNameWithIndex(config.ScalerIndex, kedautil.NormalizeString(fmt.Sprintf("activemq-%s", meta.destinationName)))
+
+	meta.scalerIndex = config.ScalerIndex
+
+	return &meta, nil
+}
+
+func (s *activeMQScaler) IsActive(ctx context.Context) (bool, error) {
+	queueSize, err := s.getQueueMessageCount(ctx)
+	if err != nil {
+		activeMQLog.Error(err, "Unable to access activeMQ management endpoint", "managementEndpoint", s.metadata.managementEndpoint)
+		return false, err
+	}
+
+	return queueSize > 0, nil
+}
+
+// getRestAPIParameters parse restAPITemplate to provide managementEndpoint, brokerName, destinationName
+func getRestAPIParameters(meta activeMQMetadata) (activeMQMetadata, error) {
+	u, err := url.ParseRequestURI(meta.restAPITemplate)
+	if err != nil {
+		return meta, fmt.Errorf("unable to parse ActiveMQ restAPITemplate: %s", err)
+	}
+
+	meta.managementEndpoint = u.Host
+	splitURL := strings.Split(strings.Split(u.Path, ":")[1], "/")[0] // This returns : type=Broker,brokerName=<<brokerName>>,destinationType=Queue,destinationName=<<destinationName>>
+	replacer := strings.NewReplacer(",", "&")
+	v, err := url.ParseQuery(replacer.Replace(splitURL)) // This returns a map with key: string types and element type [] string. : map[brokerName:[<<brokerName>>] destinationName:[<<destinationName>>] destinationType:[Queue] type:[Broker]]
+	if err != nil {
+		return meta, fmt.Errorf("unable to parse ActiveMQ restAPITemplate: %s", err)
+	}
+
+	if len(v["destinationName"][0]) == 0 {
+		return meta, errors.New("no destinationName is given")
+	}
+	meta.destinationName = v["destinationName"][0]
+
+	if len(v["brokerName"][0]) == 0 {
+		return meta, fmt.Errorf("no brokerName given: %s", meta.restAPITemplate)
+	}
+	meta.brokerName = v["brokerName"][0]
+
+	return meta, nil
+}
+
+func (s *activeMQScaler) getMonitoringEndpoint() (string, error) {
+	var buf bytes.Buffer
+	endpoint := map[string]string{
+		"ManagementEndpoint": s.metadata.managementEndpoint,
+		"BrokerName":         s.metadata.brokerName,
+		"DestinationName":    s.metadata.destinationName,
+	}
+	template, err := template.New("monitoring_endpoint").Parse(defaultActiveMQRestAPITemplate)
+	if err != nil {
+		return "", fmt.Errorf("error parsing template: %s", err)
+	}
+	err = template.Execute(&buf, endpoint)
+	if err != nil {
+		return "", fmt.Errorf("error executing template: %s", err)
+	}
+	monitoringEndpoint := buf.String()
+	return monitoringEndpoint, nil
+}
+
+func (s *activeMQScaler) getQueueMessageCount(ctx context.Context) (int, error) {
+	var monitoringInfo *activeMQMonitoring
+	var queueMessageCount int
+
+	client := s.httpClient
+	url, err := s.getMonitoringEndpoint()
+	if err != nil {
+		return -1, err
+	}
+
+	req, err := http.NewRequestWithContext(ctx, "GET", url, nil)
+	if err != nil {
+		return -1, err
+	}
+
+	// Add HTTP Auth and Headers
+	req.SetBasicAuth(s.metadata.username, s.metadata.password)
+	req.Header.Set("Content-Type", "application/json")
+
+	resp, err := client.Do(req)
+	if err != nil {
+		return -1, err
+	}
+
+	defer resp.Body.Close()
+
+	if err := json.NewDecoder(resp.Body).Decode(&monitoringInfo); err != nil {
+		return -1, err
+	}
+	if resp.StatusCode == 200 && monitoringInfo.Status == 200 {
+		queueMessageCount = monitoringInfo.MsgCount
+	} else {
+		return -1, fmt.Errorf("ActiveMQ management endpoint response error code : %d %d", resp.StatusCode, monitoringInfo.Status)
+	}
+
+	activeMQLog.V(1).Info(fmt.Sprintf("ActiveMQ scaler: Providing metrics based on current queue size %d queue size limit %d", queueMessageCount, s.metadata.targetQueueSize))
+
+	return queueMessageCount, nil
+}
+
+// GetMetricSpecForScaling returns the MetricSpec for the Horizontal Pod Autoscaler
+func (s *activeMQScaler) GetMetricSpecForScaling(context.Context) []v2beta2.MetricSpec {
+	targetMetricValue := resource.NewQuantity(int64(s.metadata.targetQueueSize), resource.DecimalSI)
+	externalMetric := &v2beta2.ExternalMetricSource{
+		Metric: v2beta2.MetricIdentifier{
+			Name: s.metadata.metricName,
+		},
+		Target: v2beta2.MetricTarget{
+			Type:         v2beta2.AverageValueMetricType,
+			AverageValue: targetMetricValue,
+		},
+	}
+	metricSpec := v2beta2.MetricSpec{
+		External: externalMetric, Type: externalMetricType,
+	}
+	return []v2beta2.MetricSpec{metricSpec}
+}
+
+func (s *activeMQScaler) GetMetrics(ctx context.Context, metricName string, metricSelector labels.Selector) ([]external_metrics.ExternalMetricValue, error) {
+	queueSize, err := s.getQueueMessageCount(ctx)
+	if err != nil {
+		return nil, fmt.Errorf("error inspecting ActiveMQ queue size: %s", err)
+	}
+
+	metric := external_metrics.ExternalMetricValue{
+		MetricName: metricName,
+		Value:      *resource.NewQuantity(int64(queueSize), resource.DecimalSI),
+		Timestamp:  metav1.Now(),
+	}
+
+	return []external_metrics.ExternalMetricValue{metric}, nil
+}
+
+func (s *activeMQScaler) Close(context.Context) error {
+	return nil
+}