Trigger Specification

This specification describes the cassandra trigger that scales based on the outputs of a Cassandra query.

triggers:
  - type: cassandra
    metadata:
      username: "cassandra"
      port: "9042"
      clusterIPAddress: "cassandra.default"
      consistency: "Quorum"
      protocolVersion: "4"
      keyspace: "test_keyspace"
      query: "SELECT COUNT(*) FROM test_keyspace.test_table;"
      targetQueryValue: "1"
      activationTargetQueryValue: "10"

Parameter list:

• username - The username credential for connecting to the Cassandra instance.
• port - The port number of the Cassandra instance. (Optional, Can be set either here or in clusterIPAddress)
• clusterIPAddress - The IP address or the host name of the Cassandra instance.
• consistency - Configuration for a session or per individual read operation. (Values: LOCAL_ONE, LOCAL_QUORUM, EACH_QUORUM, LOCAL_SERIAL, ONE, TWO, THREE, QUORUM, SERIAL, ALL, Default: ONE, Optional)
• protocolVersion - CQL Binary Protocol. (Default: 4, Optional)
• keyspace - The name of the keyspace used in Cassandra.
• query - A Cassandra query that should return single numeric value.
• targetQueryValue - The threshold value that is provided by the user and used as targetValue or targetAverageValue (depending on the trigger metric type) in the Horizontal Pod Autoscaler (HPA).
• activationTargetQueryValue - Target value for activating the scaler. Learn more about activation here. (Default: 0, Optional)

Authentication Parameters

You can authenticate by using a password via TriggerAuthentication configuration.

Password Authentication:

• password - Password for configured user to log in to the Cassandra instance.
• tls - To enable SSL auth for Cassandra session, set this to enable. If not set, TLS for Cassandra is not used. (Values: enable, disable, Default: disable, Optional).
• cert - Certificate path for client authentication. Mandatory if tls enabled. (Optional)
• key - Key path for client authentication. Mandatory if tls enabled. (Optional)

Example with no TLS auth

apiVersion: v1
kind: Secret
metadata:
  name: cassandra-secrets
type: Opaque
data:
  cassandra_password: CASSANDRA_PASSWORD
---
apiVersion: keda.sh/v1alpha1
kind: TriggerAuthentication
metadata:
  name: keda-trigger-auth-cassandra-secret
spec:
  secretTargetRef:
  - parameter: password
    name: cassandra-secrets
    key: cassandra_password
---
apiVersion: keda.sh/v1alpha1
kind: ScaledObject
metadata:
  name: cassandra-scaledobject
spec:
  scaleTargetRef:
    name: nginx-deployment
  triggers:
  - type: cassandra
    metadata:
      username: "cassandra"
      port: "9042"
      clusterIPAddress: "cassandra.default"
      consistency: "Quorum"
      protocolVersion: "4"
      query: "SELECT COUNT(*) FROM test_keyspace.test_table;"
      targetQueryValue: "1"
    authenticationRef:
      name: keda-trigger-auth-cassandra-secret

Example with TLS auth

Since we are passing Cert and Key content as inputs to the scaler, we have to supply writable location for required GSSAPI configurations for the keda-operator container.

sasl/gssapi in manager.yaml

If you use YAML declarations to deploy KEDA, add below volume mount and volume to supply writable location for required GSSAPI configurations for the keda-operator container.

          volumeMounts:
          - mountPath: /tmp/cassandra
            name: temp-cassandra-vol
            readOnly: false

      volumes:
      - name: temp-cassandra-vol
        emptyDir:
          medium: Memory

sasl/gssapi in keda-charts

If you use Helm Charts to deploy KEDA, add below volume mount and volume to supply writable location for required gssapi configurations.

volumes.keda.extraVolumeMounts
- mountPath: /tmp/cassandra
  name: temp-cassandra-vol
  readOnly: false

volumes.keda.extraVolumes
- name: temp-cassandra-vol
  emptyDir:
    medium: Memory

Once we have the writable mount path set up for the certificates and keys.

apiVersion: v1
kind: Secret
metadata:
  name: cassandra-secrets
type: Opaque
data:
  cassandra_password: CASSANDRA_PASSWORD
  tls: enable
  cert: <cert content | base64encoded>
  key: <key content | base64encoded>
  ## Optional parameter ca ##
  ca: <ca cert content | base64encoded>
---
apiVersion: keda.sh/v1alpha1
kind: TriggerAuthentication
metadata:
  name: keda-trigger-auth-cassandra-secret
spec:
  secretTargetRef:
  - parameter: password
    name: cassandra-secrets
    key: cassandra_password
  - parameter: tls
    name: cassandra-secrets
    key: tls
  - parameter: cert
    name: cassandra-secrets
    key: cert
  - parameter: key
    name: cassandra-secrets
    key: key
  ## Optional parameter ca ##
  - parameter: ca
    name: cassandra-secrets
    key: ca
---
apiVersion: keda.sh/v1alpha1
kind: ScaledObject
metadata:
  name: cassandra-scaledobject
spec:
  scaleTargetRef:
    name: nginx-deployment
  triggers:
  - type: cassandra
    metadata:
      username: "cassandra"
      port: "9042"
      clusterIPAddress: "cassandra.default"
      consistency: "Quorum"
      protocolVersion: "4"
      query: "SELECT COUNT(*) FROM test_keyspace.test_table;"
      targetQueryValue: "1"
    authenticationRef:
      name: keda-trigger-auth-cassandra-secret