Add Cassandra Scaler

.gitignore

@@ -44,3 +44,6 @@ cover.out
 
 # GO debug binary
 cmd/manager/debug.test
+
+# pre-commit
+.pre-commit-config.yaml

.pre-commit-config.yaml

@@ -2,20 +2,20 @@ default_stages: [commit, push]
 minimum_pre_commit_version: "1.20.0"
 repos:
   - repo: git://github.com/dnephin/pre-commit-golang
-    rev: v0.3.5
+    rev: v0.4.0
     hooks:
       - id: go-fmt
         name: Run go fmt against the code
   - repo: https://github.com/pre-commit/pre-commit-hooks
-    rev: v3.4.0
+    rev: v4.0.1
     hooks:
       - id: trailing-whitespace
       - id: detect-private-key
       - id: end-of-file-fixer
       - id: check-merge-conflict
       - id: mixed-line-ending
   - repo: https://github.com/thlorenz/doctoc.git
-    rev: v2.0.0
+    rev: v2.1.0
     hooks:
       - id: doctoc
         name: Add TOC for md files

go.mod

@@ -21,6 +21,7 @@ require (
 	github.com/go-redis/redis v6.15.9+incompatible
 	github.com/go-sql-driver/mysql v1.6.0
 	github.com/golang/mock v1.6.0
+	github.com/gocql/gocql v0.0.0-20210515062232-b7ef815b4556
 	github.com/golang/protobuf v1.5.2
 	github.com/google/go-cmp v0.5.6
 	github.com/hashicorp/vault/api v1.1.1

go.sum

@@ -168,10 +168,13 @@ github.com/beorn7/perks v1.0.1 h1:VlbKKnNfV8bJzeqoa4cOKqO6bYr3WgKZxO8Z16+hsOM=
 github.com/beorn7/perks v1.0.1/go.mod h1:G2ZrVWU2WbWT9wwq4/hrbKbnv/1ERSJQ0ibhJ6rlkpw=
 github.com/bgentry/speakeasy v0.1.0/go.mod h1:+zsyZBPWlz7T6j88CTgSN5bM796AkVf0kBD4zp0CCIs=
 github.com/bketelsen/crypt v0.0.3-0.20200106085610-5cbc8cc4026c/go.mod h1:MKsuJmJgSg28kpZDP6UIiPt0e0Oz0kqKNGyRaWEPv84=
+github.com/bitly/go-hostpool v0.0.0-20171023180738-a3a6125de932/go.mod h1:NOuUCSz6Q9T7+igc/hlvDOUdtWKryOrtFyIVABv/p7k=
+github.com/blang/semver v3.5.0+incompatible/go.mod h1:kRBLl5iJ+tD4TcOOxsy/0fnwebNt5EWlYSAyrTnjyyk=
 github.com/blang/semver v3.5.1+incompatible h1:cQNTCjp13qL8KC3Nbxr/y2Bqb63oX6wdnnjpJbkM4JQ=
 github.com/blang/semver v3.5.1+incompatible/go.mod h1:kRBLl5iJ+tD4TcOOxsy/0fnwebNt5EWlYSAyrTnjyyk=
 github.com/blang/semver/v4 v4.0.0/go.mod h1:IbckMUScFkM3pff0VJDNKRiT6TG/YpiHIM2yvyW5YoQ=
 github.com/blendle/zapdriver v1.3.1/go.mod h1:mdXfREi6u5MArG4j9fewC+FGnXaBR+T4Ox4J2u4eHCc=
+github.com/bmizerany/assert v0.0.0-20160611221934-b7ed37b82869/go.mod h1:Ekp36dRnpXw/yCqJaO+ZrUyxD+3VXMFFr56k5XYrpB4=
 github.com/bmizerany/perks v0.0.0-20141205001514-d9a9656a3a4b/go.mod h1:ac9efd0D1fsDb3EJvhqgXRbFx7bs2wqZ10HQPeU8U/Q=
 github.com/c2h5oh/datasize v0.0.0-20171227191756-4eba002a5eae/go.mod h1:S/7n9copUssQ56c7aAgHqftWO4LTf4xY6CGWt8Bc+3M=
 github.com/cenkalti/backoff/v3 v3.0.0 h1:ske+9nBpD9qZsTBoF41nW5L+AIuFBKMeze18XQ3eG1c=
@@ -394,6 +397,8 @@ github.com/gobwas/ws v1.0.2/go.mod h1:szmBTxLgaFppYjEmNtny/v3w89xOydFnnZMcgRRu/E
 github.com/godbus/dbus v0.0.0-20190422162347-ade71ed3457e/go.mod h1:bBOAhwG1umN6/6ZUMtDFBMQR8jRg9O75tm9K00oMsK4=
 github.com/godbus/dbus/v5 v5.0.4/go.mod h1:xhWf0FNVPg57R7Z0UbKHbJfkEywrmjJnf7w5xrFpKfA=
 github.com/gogo/googleapis v1.1.0/go.mod h1:gf4bu3Q80BeJ6H1S1vYPm8/ELATdvryBaNFGgqEef3s=
+github.com/gocql/gocql v0.0.0-20210515062232-b7ef815b4556 h1:N/MD/sr6o61X+iZBAT2qEUF023s4KbA8RWfKzl0L6MQ=
+github.com/gocql/gocql v0.0.0-20210515062232-b7ef815b4556/go.mod h1:DL0ekTmBSTdlNF25Orwt/JMzqIq3EJ4MVa/J/uK64OY=
 github.com/gogo/protobuf v1.1.1/go.mod h1:r8qH/GZQm5c6nD/R0oafs1akxWv10x8SbQlK7atdtwQ=
 github.com/gogo/protobuf v1.2.0/go.mod h1:r8qH/GZQm5c6nD/R0oafs1akxWv10x8SbQlK7atdtwQ=
 github.com/gogo/protobuf v1.2.1/go.mod h1:hp+jE20tsWTFYpLwKvXlhS1hjn+gTNwPg2I6zVXpSg4=
@@ -438,6 +443,7 @@ github.com/golang/protobuf v1.5.0/go.mod h1:FsONVRAS9T7sI+LIUmWTfcYkHO4aIWwzhcaS
 github.com/golang/protobuf v1.5.1/go.mod h1:DopwsBzvsk0Fs44TXzsVbJyPhcCPeIwnvohx4u74HPM=
 github.com/golang/protobuf v1.5.2 h1:ROPKBNFfQgOUMifHyP+KYbvpjbdoFNs+aK7DXlji0Tw=
 github.com/golang/protobuf v1.5.2/go.mod h1:XVQd3VNwM+JqD3oG2Ue2ip4fOMUkwXdXDdiuN0vRsmY=
+github.com/golang/snappy v0.0.0-20170215233205-553a64147049/go.mod h1:/XxbfmMg8lxefKM7IXC3fBNl/7bRcc72aCRzEWrmP2Q=
 github.com/golang/snappy v0.0.0-20180518054509-2e65f85255db/go.mod h1:/XxbfmMg8lxefKM7IXC3fBNl/7bRcc72aCRzEWrmP2Q=
 github.com/golang/snappy v0.0.1/go.mod h1:/XxbfmMg8lxefKM7IXC3fBNl/7bRcc72aCRzEWrmP2Q=
 github.com/golang/snappy v0.0.3/go.mod h1:/XxbfmMg8lxefKM7IXC3fBNl/7bRcc72aCRzEWrmP2Q=
@@ -535,6 +541,9 @@ github.com/grpc-ecosystem/grpc-gateway v1.14.6/go.mod h1:zdiPV4Yse/1gnckTHtghG4G
 github.com/grpc-ecosystem/grpc-gateway v1.16.0 h1:gmcG1KaJ57LophUzW0Hy8NmPhnMZb4M0+kPpLofRdBo=
 github.com/grpc-ecosystem/grpc-gateway v1.16.0/go.mod h1:BDjrQk3hbvj6Nolgz8mAMFbcEtjT1g+wF4CSlocrBnw=
 github.com/hashicorp/consul/api v1.1.0/go.mod h1:VmuI/Lkw1nC05EYQWNKwWGbkg+FbDBtguAZLlVdkD9Q=
+github.com/hailocab/go-hostpool v0.0.0-20160125115350-e80d13ce29ed h1:5upAirOpQc1Q53c0bnx2ufif5kANL7bfZWcc6VJWJd8=
+github.com/hailocab/go-hostpool v0.0.0-20160125115350-e80d13ce29ed/go.mod h1:tMWxXQ9wFIaZeTI9F+hmhFiGpFmhOHzyShyFUhRm0H4=
+github.com/hashicorp/consul/api v1.3.0/go.mod h1:MmDNSzIMUjNpY/mQ398R4bk2FnqQLoPndWW5VkKPlCE=
 github.com/hashicorp/consul/sdk v0.1.1/go.mod h1:VKf9jXwCTEY1QZP2MOLRhb5i/I/ssyNV1vwHyQBF0x8=
 github.com/hashicorp/errwrap v1.0.0 h1:hLrqtEDnRye3+sgx6z4qVLNuviH3MR5aQ0ykNJa/UYA=
 github.com/hashicorp/errwrap v1.0.0/go.mod h1:YH+1FKiLXxHSkmPseP+kNlulaMuP3n2brvKWEqk/Jc4=

pkg/scalers/cassandra_scaler.go

@@ -0,0 +1,225 @@
+package scalers
+
+import (
+	"context"
+	"fmt"
+	"strconv"
+	"strings"
+
+	"github.com/gocql/gocql"
+	kedautil "github.com/kedacore/keda/v2/pkg/util"
+	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"
+)
+
+// cassandraScaler exposes a data pointer to CassandraMetadata and gocql.Session connection.
+type cassandraScaler struct {
+	metadata *CassandraMetadata
+	session  *gocql.Session
+}
+
+// CassandraMetadata defines metadata used by KEDA to query a Cassandra table.
+type CassandraMetadata struct {
+	username         string
+	password         string
+	clusterIPAddress string
+	port             int
+	consistency      gocql.Consistency
+	protocolVersion  int
+	keyspace         string
+	query            string
+	targetQueryValue int
+	metricName       string
+}
+
+var cassandraLog = logf.Log.WithName("cassandra_scaler")
+
+// NewCassandraScaler creates a new Cassandra scaler.
+func NewCassandraScaler(config *ScalerConfig) (Scaler, error) {
+	meta, err := ParseCassandraMetadata(config)
+	if err != nil {
+		return nil, fmt.Errorf("error parsing cassandra metadata: %s", err)
+	}
+
+	session, err := NewCassandraSession(meta)
+	if err != nil {
+		return nil, fmt.Errorf("error establishing cassandra session: %s", err)
+	}
+
+	return &cassandraScaler{
+		metadata: meta,
+		session:  session,
+	}, nil
+}
+
+// ParseCassandraMetadata parses the metadata and returns a CassandraMetadata or an error if the ScalerConfig is invalid.
+func ParseCassandraMetadata(config *ScalerConfig) (*CassandraMetadata, error) {
+	meta := CassandraMetadata{}
+
+	if val, ok := config.TriggerMetadata["query"]; ok {
+		meta.query = val
+	} else {
+		return nil, fmt.Errorf("no query given")
+	}
+
+	if val, ok := config.TriggerMetadata["targetQueryValue"]; ok {
+		targetQueryValue, err := strconv.Atoi(val)
+		if err != nil {
+			return nil, fmt.Errorf("targetQueryValue parsing error %s", err.Error())
+		}
+		meta.targetQueryValue = targetQueryValue
+	} else {
+		return nil, fmt.Errorf("no targetQueryValue given")
+	}
+
+	if val, ok := config.TriggerMetadata["username"]; ok {
+		meta.username = val
+	} else {
+		return nil, fmt.Errorf("no username given")
+	}
+
+	if val, ok := config.TriggerMetadata["port"]; ok {
+		port, err := strconv.Atoi(val)
+		if err != nil {
+			return nil, fmt.Errorf("port parsing error %s", err.Error())
+		}
+		meta.port = port
+	}
+
+	if val, ok := config.TriggerMetadata["clusterIPAddress"]; ok {
+		switch p := meta.port; {
+		case p > 0:
+			meta.clusterIPAddress = fmt.Sprintf("%s:%d", val, meta.port)
+		case strings.Contains(val, ":"):
+			meta.clusterIPAddress = val
+		default:
+			return nil, fmt.Errorf("no port given")
+		}
+	} else {
+		return nil, fmt.Errorf("no cluster IP address given")
+	}
+
+	if val, ok := config.TriggerMetadata["protocolVersion"]; ok {
+		protocolVersion, err := strconv.Atoi(val)
+		if err != nil {
+			return nil, fmt.Errorf("protocolVersion parsing error %s", err.Error())
+		}
+		meta.protocolVersion = protocolVersion
+	} else {
+		meta.protocolVersion = 4
+	}
+
+	if val, ok := config.TriggerMetadata["consistency"]; ok {
+		meta.consistency = gocql.ParseConsistency(val)
+	} else {
+		meta.consistency = gocql.One
+	}
+
+	if val, ok := config.TriggerMetadata["keyspace"]; ok {
+		meta.keyspace = val
+	} else {
+		return nil, fmt.Errorf("no keyspace given")
+	}
+
+	if val, ok := config.TriggerMetadata["metricName"]; ok {
+		meta.metricName = kedautil.NormalizeString(fmt.Sprintf("cassandra-%s", val))
+	} else {
+		meta.metricName = kedautil.NormalizeString(fmt.Sprintf("cassandra-%s", meta.keyspace))
+	}
+
+	if val, ok := config.AuthParams["password"]; ok {
+		meta.password = val
+	} else {
+		return nil, fmt.Errorf("no password given")
+	}
+
+	return &meta, nil
+}
+
+// NewCassandraSession returns a new Cassandra session for the provided CassandraMetadata.
+func NewCassandraSession(meta *CassandraMetadata) (*gocql.Session, error) {
+	cluster := gocql.NewCluster(meta.clusterIPAddress)
+	cluster.ProtoVersion = meta.protocolVersion
+	cluster.Consistency = meta.consistency
+	cluster.Authenticator = gocql.PasswordAuthenticator{
+		Username: meta.username,
+		Password: meta.password,
+	}
+
+	session, err := cluster.CreateSession()
+	if err != nil {
+		cassandraLog.Error(err, "found error creating session")
+		return nil, err
+	}
+
+	return session, nil
+}
+
+// IsActive returns true if there are pending events to be processed.
+func (s *cassandraScaler) IsActive(ctx context.Context) (bool, error) {
+	messages, err := s.GetQueryResult()
+	if err != nil {
+		return false, fmt.Errorf("error inspecting cassandra: %s", err)
+	}
+
+	return messages > 0, nil
+}
+
+// GetMetricSpecForScaling returns the MetricSpec for the Horizontal Pod Autoscaler.
+func (s *cassandraScaler) GetMetricSpecForScaling() []v2beta2.MetricSpec {
+	targetQueryValue := resource.NewQuantity(int64(s.metadata.targetQueryValue), resource.DecimalSI)
+	externalMetric := &v2beta2.ExternalMetricSource{
+		Metric: v2beta2.MetricIdentifier{
+			Name: s.metadata.metricName,
+		},
+		Target: v2beta2.MetricTarget{
+			Type:         v2beta2.AverageValueMetricType,
+			AverageValue: targetQueryValue,
+		},
+	}
+	metricSpec := v2beta2.MetricSpec{
+		External: externalMetric, Type: externalMetricType,
+	}
+
+	return []v2beta2.MetricSpec{metricSpec}
+}
+
+// GetMetrics returns a value for a supported metric or an error if there is a problem getting the metric.
+func (s *cassandraScaler) GetMetrics(ctx context.Context, metricName string, metricSelector labels.Selector) ([]external_metrics.ExternalMetricValue, error) {
+	num, err := s.GetQueryResult()
+	if err != nil {
+		return []external_metrics.ExternalMetricValue{}, fmt.Errorf("error inspecting cassandra: %s", err)
+	}
+
+	metric := external_metrics.ExternalMetricValue{
+		MetricName: metricName,
+		Value:      *resource.NewQuantity(int64(num), resource.DecimalSI),
+		Timestamp:  metav1.Now(),
+	}
+
+	return append([]external_metrics.ExternalMetricValue{}, metric), nil
+}
+
+// GetQueryResult returns the result of the scaler query.
+func (s *cassandraScaler) GetQueryResult() (int, error) {
+	var value int
+	if err := s.session.Query(s.metadata.query).Scan(&value); err != nil {
+		if err != gocql.ErrNotFound {
+			cassandraLog.Error(err, "query failed")
+			return 0, err
+		}
+	}
+
+	return value, nil
+}
+
+// Close closes the Cassandra session connection.
+func (s *cassandraScaler) Close() error {
+	s.session.Close()
+
+	return nil
+}