Sink CRD configurations

This document lists CRD configurations available for Pulsar sink connectors. The sink CRD configurations consist of sink connector configurations and the common CRD configurations.

Sink configurations

This table lists sink configurations.

Field	Description
name	The connector name is a string of up to 43 characters.
classname	The class name of a sink connector.
tenant	The tenant of a sink connector.
namespace	The Pulsar namespace of a sink connector.
clusterName	The Pulsar cluster of a sink connector.
replicas	The number of instances that you want to run for a sink connector. If it is set to 0, it means to stop the sink connector. When HPA is enabled, you cannot set the replicas parameter to 0 or a negative number.
ShowPreciseParallelism	Configure whether to show the precise parallelism. If it is set to true, the Parallelism is equal to value of the replicas parameter. In this situation, when you update the value of the replicas parameter, it will cause all Pods to be recreated. By default, it is set to false.
minReplicas	The minimum number of instances that you want to run for a sink connector. If it is set to 0, it means to stop the sink connector. By default, it is set to 1. When HPA auto-scaling is enabled, the HPA controller scales the Pods up / down based on the values of the minReplicas and maxReplicas options. The number of the Pods should be greater than the value of the minReplicas and be smaller than the value of the maxReplicas.
downloaderImage	The image for installing the init container that is used to download packages or functions from Pulsar if the download path is specified.
maxReplicas	The maximum number of instances that you want to run for this sink connector. When the value of the maxReplicas parameter is greater than the value of replicas, it indicates that the sink controller automatically scales the sink connector based on the CPU usage. By default, maxReplicas is set to 0, which indicates that auto-scaling is disabled.
sinkConfig	The sink connector configurations in YAML format.
timeout	The message timeout in milliseconds.
negativeAckRedeliveryDelayMs	The number of redelivered messages due to negative acknowledgement.
autoAck	Whether or not the framework acknowledges messages automatically. This field is required. You can set it to true or false.
maxMessageRetry	How many times to process a message before giving up.
processingGuarantee	The processing guarantees (delivery semantics) applied to the sink connector. Available values: atleast_once, atmost_once, effectively_once. When you set ProcessingGuarantees to effectively_once, the runtime will set the subscription type to FAILOVER. By default, the subscription type is set to SHARED.
retainOrdering	The sink connector consumes and processes messages in order. When you set retainOrdering, the runtime will set the subscription type to FAILOVER. By default, the subscription type is set to SHARED.
retainKeyOrdering	Configure whether to retain the key order of messages. When you set retainKeyOrdering, the runtime will set the subscription type to KEY_SHARED. By default, the subscription type is set to SHARED.
deadLetterTopic	The topic where all messages that were not processed successfully are sent.
subscriptionName	The subscription name of the sink connector if you want a specific subscription name for the input-topic consumer.
cleanupSubscription	Configure whether to clean up subscriptions.
subscriptionPosition	The subscription position.
pulsar	The configurations of the Pulsar cluster. For details, see messaging.

Annotations

In Kubernetes, an annotation defines an unstructured Key Value Map (KVM) that can be set by external tools to store and retrieve metadata. annotations must be a map of string keys and string values. Annotation values must pass Kubernetes annotations validation. For details, see Kubernetes documentation on Annotations.

This example shows how to use an annotation to make an object unmanaged. Therefore, the Controller will skip reconciling unmanaged objects in reconciliation loop.

apiVersion: compute.functionmesh.io/v1alpha1
kind: Sink
metadata:
  annotations:
    compute.functionmesh.io/managed: "false"

Images

This section describes image options available for Pulsar sink CRDs.

Base runner

The base runner is an image base for other runners. The base runner is located at ./pulsar-functions-base-runner. The base runner image contains basic tool-chains like /pulsar/bin, /pulsar/conf and /pulsar/lib to ensure that the pulsar-admin CLI tool works properly to support Apache Pulsar Packages.

Runner images

Function Mesh uses runner images as images of Pulsar connectors. Each runner image only contains necessary tool-chains and libraries for specified runtime.

Pulsar connectors support using the Java runner images as their images. The Java runner is based on the base runner and contains the Java function instance to run Java functions or connectors. The streamnative/pulsar-functions-java-runner Java runner is stored at the Docker Hub and is automatically updated to align with Apache Pulsar release.

Image pull policies

When the Function Mesh Operator creates a container, it uses the imagePullPolicy option to determine whether the image should be pulled prior to starting the container. There are three possible values for the imagePullPolicy option:

Field	Description
Always	Always pull the image.
Never	Never pull the image.
IfNotPresent	Only pull the image if the image does not already exist locally.

Messaging

Function Mesh provides Pulsar cluster configurations in the Function, Source, and Sink CRDs. You can configure TLS encryption, TLS authentication, and OAuth2 authentication using the following configurations.

Note

The tlsConfig and tlsSecret are exclusive. If you configure TLS configurations, the TLS Secret will not take effect.

Field	Description
authConfig	The authentication configurations of the Pulsar cluster. Currently, you can only configure OAuth2 authentication through this field. For other authentication methods, you can configure them using the authSecret field. audience: specify the OAuth2 resource server identifier for the Pulsar cluster. issuerUrl: specify the URL of the OAuth2 identity provider that allows a Pulsar client to obtain an access token. scope: specify the scope of an access request. For more information, see access token scope. keySecretName: specify the name of the Kubernetes Secret. keySecretKey: specify the key of the Kubernetes Secret that contains the content of the OAuth2 private key.
authSecret	The name of the authentication ConfigMap that stores authentication configurations of the Pulsar cluster. clientAuthenticationPlugin: specify the client authentication plugin. clientAuthenticationParameters: specify the client authentication parameters.
pulsarConfig	The name of the ConfigMap that stores Pulsar cluster configurations. webServiceURL: specify the web service URL for managing the Pulsar cluster. This URL should be a standard DNS name. brokerServiceURL: specify the Pulsar protocol URL for interaction with the brokers in the Pulsar cluster. This URL should not use the same DNS name as the web service URL but should use the pulsar scheme.
tlsConfig	The TLS configurations of the Pulsar cluster. allowInsecure: allow insecure TLS connection. certSecretKey: specify the TLS Secret key. certSecretName: specify the TLS Secret name. enabled: enable TLS configurations. hostnameVerification: enable hostname verification.
tlsSecret	The name of the TLS ConfigMap that stores TLS configurations of the Pulsar cluster. tlsAllowInsecureConnection: allow insecure TLS connection. By default, it is set to false. tlsHostnameVerificationEnable: enable hostname verification. By default, it is set to true. tlsTrustCertsFilePath: specify the path of the TLS trust certificate file.

State storage

Function Mesh provides the following fields for stateful configurations in the CRD definition.

Field	Description
statefulConfig	The state storage configuration for the sink connector.
statefulConfig.pulsar.serviceUrl	The service URL that points to the state storage service. By default, the state storage service is the BookKeeper table service.
statefulConfig.pulsar.javaProvider	(Optional) If you want to overwrite the default configuration, you can use the state storage configuration for the Java runtime. For example, you can change it to other backend services other than the BookKeeper table service.
statefulConfig.pulsar.javaProvider.className	The Java class name of the state storage provider implementation. The class must implement the org.apache.pulsar.functions.instance.state.StateStoreProvider interface. If not, org.apache.pulsar.functions.instance.state.BKStateStoreProviderImpl will be used.
statefulConfig.pulsar.javaProvider.config	The configurations that are passed to the state storage provider.

Input

The input topics of a Pulsar Function. The following table lists options available for the Input.

Field	Description
topics	The configuration of the topic from which messages are fetched.
customSerdeSources	The map of input topics to SerDe class names (as a JSON string).
customSchemaSources	The map of input topics to Schema class names (as a JSON string).
sourceSpecs	The map of source specifications to consumer specifications. Consumer specifications include these options: - SchemaType: the built-in schema type or custom schema class name to be used for messages fetched by the connector. - SerdeClassName: the SerDe class to be used for messages fetched by the connector. - IsRegexPattern: configure whether the input topic adopts a Regex pattern. - SchemaProperties: the schema properties for messages fetched by the connector. - ConsumerProperties: the consumer properties for messages fetched by the connector. - ReceiverQueueSize: the size of the consumer receive queue. - cryptoConfig: cryptography configurations of the consumer.

Resources

When you specify a function or connector, you can optionally specify how much of each resource they need. The resources available to specify are CPU and memory (RAM).

If the node where a Pod is running has enough of a resource available, it is possible (and allowed) for a Pod to use more resources than its request for that resource. However, a Pod is not allowed to use more than its resource limit.

Secrets

Function Mesh provides the secretsMap field for Function, Source, and Sink in the CRD definition. You can refer to the created secrets under the same namespace and the controller can include those referred secrets. The secrets are provide by EnvironmentBasedSecretsProvider, which can be used by context.getSecret() in Pulsar functions and connectors.

The secretsMap field is defined as a Map struct with String keys and SecretReference values. The key indicates the environment value in the container, and the SecretReference is defined as below.

Field	Description
path	The name of the secret in the Pod's namespace to select from.
key	The key of the secret to select from. It must be a valid secret key.

Suppose that there is a Kubernetes Secret named credential-secret defined as below:

apiVersion: v1
data:
  username: foo
  password: bar
kind: Secret
metadata:
  name: credential-secret
type: Opaque

To use it in Pulsar Functions in a secure way, you can define the secretsMap in the Custom Resource:

secretsMap:
  username:
    path: credential-secret
    key: username
  password:
    path: credential-secret
    key: password

Then, in the Pulsar Functions and Connectors, you can call context.getSecret("username") to get the secret value (foo).

Packages

Function Mesh supports running Pulsar connectors in Java.

Field	Description
jarLocation	The path to the JAR file for the connector.
javaOpts	It specifies JVM options to better configure JVM behaviors, including exitOnOOMError, Garbage Collection logs, Garbage Collection tuning, and so on.
extraDependenciesDir	It specifies the dependent directory for the JAR package.

Cluster location

In Function Mesh, the Pulsar cluster is defined through a ConfigMap. Pods can consume ConfigMaps as environment variables in a volume. The Pulsar cluster ConfigMap defines the Pulsar cluster URLs.

Field	Description
webServiceURL	The Web service URL of the Pulsar cluster.
brokerServiceURL	The broker service URL of the Pulsar cluster.

Health checks

Note

To enable health checks, you need to create a PVC and a PV, and bind the PVC to the PV.

With the Kubernetes liveness probe, Function Mesh supports monitoring and acting on the state of Pods (Containers) to ensure that only healthy Pods serve traffic. Implementing health checks using probes provides Function Mesh a solid foundation, better reliability, and higher uptime.

apiVersion: compute.functionmesh.io/v1alpha1
kind: Function
metadata:
  name: health-check-sample
  namespace: default
spec:
  image: streamnative/pulsar-functions-java-sample:2.9.2.23
  className: org.apache.pulsar.functions.api.examples.ExclamationFunction
  forwardSourceMessageProperty: true
  maxPendingAsyncRequests: 1000
  replicas: 1
  maxReplicas: 5
  logTopic: persistent://public/default/logging-function-logs
  pod:
    liveness:
      failureThreshold:              # --- [1]
      initialDelaySeconds: 10        # --- [2]
      periodSeconds: 10              # --- [3]
      successThreshold: 1            # --- [4]
... 
# Other configs

• [1] failureThreshold: specify the times to restart a failed probe before giving up the probe. By default, it is set to 3.
• [2] initialDelaySeconds: specify the time that should wait before performing the first liveness probe.
• [3] periodSeconds: specify the frequency to perform a liveness probe.
• [4] successThreshold: specify the minimum consecutive successes for the probe to be considered successful after having failed. By default, it is set to 1.

For more information about probe types, probe check mechanisms, and probe parameters, see Kubernetes documentation on Pod lifecycle and configure probes.

Security context

A security context defines privilege and access control settings for a Pod. By default, Function Mesh uses the following PodSecurityContext as the default value and applies to every function's Pod.

podSecurityContext:
     fsGroup: 10001
     runAsGroup: 10001
     runAsNonRoot: false
     runAsUser: 10000
     seccompProfile:
          type: "RuntimeDefault"

Apart from the PodSecurityContext, Function Mesh also applies the following SecurityContext to the Function's container to ensure the Pod Security Standard follows the restricted specification.

SecurityContext:
     capabilities:
          drop: 
               - ALL
      allowPrivilegeEscalation: false

Field	Description
fsGroup	A special supplemental group that applies to all containers in a Pod.
fsGroupChangePolicy	Define the behavior of changing ownership and permission of the volume before being exposed inside a Pod. This field only applies to volume types that support fsGroup-based ownership and permissions.
runAsGroup	The Group ID (GID) that is used to run the entry point of the container process. If it is unset, the runtime is used.
runAsNonRoot	Indicate that the container must run as a non-root user. If it is set to true, the system will validate the image at runtime to ensure that it does not run as a root user (User ID 0) and fail to start the container if it does. If it is unset or is set to false, no such validation will be performed.
runAsUser	The User ID (UID) that is used to run the entry point of the container process.
seLinuxOptions	The SELinux context that is applied to a container.
seccompProfile	The seccomp options that is used by a container.
supplementalGroups	A list of groups that is applied to the first process running in each container, in addition to the container's primary GID, the fsGroup (if specified), and group memberships defined in the container image for the UID of the container process.
sysctls	Sysctls hold a list of namespaced sysctls used for the Pod.
windowsOptions	The windows-specific settings that are applied to all containers.
allowPrivilegeEscalation	Control whether a process can gain more privileges than its parent process.
capabilities	The capabilities to add/drop when running a container.
privileged	Run the container in privileged or unprivileged mode.
procMount	The type of proc mount that is used by a container.
readOnlyRootFilesystem	Mount the container's root filesystem as read-only.

Pod specifications

Function Mesh supports customizing the Pod running Pulsar connectors. This table lists sub-fields available for the pod field.

Field	Description
labels	Specify labels attached to a Pod.
liveness	Specify the liveness probe properties for a Pod. initialDelaySecond: specify the time that should wait before performing the first liveness probe. periodSeconds: specify the frequency to perform a liveness probe. For details, see health checks.
nodeSelector	Specify a map of key-value pairs. For a Pod running on a node, the node must have each of the indicated key-value pairs as labels.
affinity	Specify the scheduling constraints of a Pod.
tolerations	Specify the tolerations of a Pod.
annotations	Specify the annotations attached to a Pod.
securityContext	Specify the security context for a Pod. For details, see [security context](#security-context).
terminationGracePeriodSeconds	The amount of time that Kubernetes gives for a Pod before terminating it.
volumes	A list of volumes that can be mounted by containers belonging to a Pod.
imagePullSecrets	An optional list of references to secrets in the same namespace for pulling any of the images used by a Pod.
serviceAccountName	Specify the name of the service account that is used to run Pulsar Functions or connectors.
initContainers	The initialization containers belonging to a Pod. A typical use case could be using an initialization container to download a remote JAR to a local path.
sidecars	Sidecar containers run together with the main function container in a Pod.
builtinAutoscaler	Specify the built-in autoscaling rules. CPU-based autoscaling: auto-scale the number of Pods based on the CPU usage (80%, 50%, or 20%). Memory-based autoscaling: auto-scale the number of Pods based on the memory usage (80%, 50%, or 20%). If you configure the builtinAutoscaler field, you do not need to configure the autoScalingMetrics and autoScalingBehavior options and vice versa.
autoScalingMetrics	Specify how to scale based on customized metrics defined in connectors. For details, see MetricSpec v2 autoscaling.
autoScalingBehavior	Configure the scaling behavior of the target in both up and down directions (scaleUp and scaleDown fields respectively). If not specified, the default Kubernetes scaling behaviors are adopted. For details, see HorizontalPodAutoscalerBehavior v2 autoscaling.
env	Specify the environment variables to expose on the containers. It is a key/value map. You can either use the value option to specify a particular value for the environment variable or use the valueFrom option to specify the source for the environment variable's value, as shown below. ```yaml env: - name: example1 value: simpleValue - name: example2 valueFrom: secretKeyRef: name: secret-name key: akey ```