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Version: 0.13.0

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.

nameThe connector name is a string of up to 43 characters.
classnameThe class name of a sink connector.
tenantThe tenant of a sink connector.
namespaceThe Pulsar namespace of a sink connector.
clusterNameThe Pulsar cluster of a sink connector.
replicasThe 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.
ShowPreciseParallelismConfigure 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.
minReplicasThe 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.
downloaderImageThe image for installing the init container that is used to download packages or functions from Pulsar if the download path is specified.
maxReplicasThe 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.
sinkConfigThe sink connector configurations in YAML format.
timeoutThe message timeout in milliseconds.
negativeAckRedeliveryDelayMsThe number of redelivered messages due to negative acknowledgement.
autoAckWhether or not the framework acknowledges messages automatically. This field is required. You can set it to true or false.
maxMessageRetryHow many times to process a message before giving up.
processingGuaranteeThe 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.
retainOrderingThe 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.
retainKeyOrderingConfigure 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.
deadLetterTopicThe topic where all messages that were not processed successfully are sent.
subscriptionNameThe subscription name of the sink connector if you want a specific subscription name for the input-topic consumer.
cleanupSubscriptionConfigure whether to clean up subscriptions.
subscriptionPositionThe subscription position.
pulsarThe configurations of the Pulsar cluster. For details, see messaging.


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.

kind: Sink
annotations: "false"


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:

AlwaysAlways pull the image.
NeverNever pull the image.
IfNotPresentOnly pull the image if the image does not already exist locally.


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.


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

authConfigThe authentication configurations of the Pulsar cluster. Currently, you can only configure generic authentication and OAuth2 authentication through this field. For other authentication methods, you can configure them using the authSecret field.

Generic authentication

  • clientAuthenticationParameters: specify the client authentication parameters.
  • clientAuthenticationPlugin: specify the client authentication plugin.

OAuth2 authentication

  • 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.
authSecretThe 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.
pulsarConfigThe 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.
tlsConfigThe 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.
tlsSecretThe 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.

statefulConfigThe state storage configuration for the sink connector.
statefulConfig.pulsar.serviceUrlThe 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.classNameThe 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.configThe configurations that are passed to the state storage provider.


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

topicsThe configuration of the topic from which messages are fetched.
customSerdeSourcesThe map of input topics to SerDe class names (as a JSON string).
customSchemaSourcesThe map of input topics to Schema class names (as a JSON string).
sourceSpecsThe 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.


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.


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.

pathThe name of the secret in the Pod's namespace to select from.
keyThe 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
username: foo
password: bar
kind: Secret
name: credential-secret
type: Opaque

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

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

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


Function Mesh supports running Pulsar connectors in Java.

jarLocationThe path to the JAR file for the connector.
javaOptsIt specifies JVM options to better configure JVM behaviors, including exitOnOOMError, Garbage Collection logs, Garbage Collection tuning, and so on.
extraDependenciesDirIt 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.

webServiceURLThe Web service URL of the Pulsar cluster.
brokerServiceURLThe broker service URL of the Pulsar cluster.

Health checks


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.

kind: Function
name: health-check-sample
namespace: default
image: streamnative/pulsar-functions-java-sample:
className: org.apache.pulsar.functions.api.examples.ExclamationFunction
forwardSourceMessageProperty: true
maxPendingAsyncRequests: 1000
replicas: 1
maxReplicas: 5
logTopic: persistent://public/default/logging-function-logs
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.

fsGroup: 10001
runAsGroup: 10001
runAsNonRoot: false
runAsUser: 10000
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.

allowPrivilegeEscalation: false
fsGroupA special supplemental group that applies to all containers in a Pod.
fsGroupChangePolicyDefine 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.
runAsGroupThe Group ID (GID) that is used to run the entry point of the container process. If it is unset, the runtime is used.
runAsNonRootIndicate 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.
runAsUserThe User ID (UID) that is used to run the entry point of the container process.
seLinuxOptionsThe SELinux context that is applied to a container.
seccompProfileThe seccomp options that is used by a container.
supplementalGroupsA 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.
sysctlsSysctls hold a list of namespaced sysctls used for the Pod.
windowsOptionsThe windows-specific settings that are applied to all containers.
allowPrivilegeEscalationControl whether a process can gain more privileges than its parent process.
capabilitiesThe capabilities to add/drop when running a container.
privilegedRun the container in privileged or unprivileged mode.
procMountThe type of proc mount that is used by a container.
readOnlyRootFilesystemMount 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.

labelsSpecify labels attached to a Pod.
livenessSpecify 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.

nodeSelectorSpecify 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.
affinitySpecify the scheduling constraints of a Pod.
tolerationsSpecify the tolerations of a Pod.
annotationsSpecify the annotations attached to a Pod.
securityContextSpecify the security context for a Pod. For details, see [security context](#security-context).
terminationGracePeriodSecondsThe amount of time that Kubernetes gives for a Pod before terminating it.
volumesA list of volumes that can be mounted by containers belonging to a Pod.
imagePullSecretsAn optional list of references to secrets in the same namespace for pulling any of the images used by a Pod.
serviceAccountNameSpecify the name of the service account that is used to run Pulsar Functions or connectors.
initContainersThe 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.
sidecarsSidecar containers run together with the main function container in a Pod.
builtinAutoscalerSpecify 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.

autoScalingMetricsSpecify how to scale based on customized metrics defined in connectors. For details, see MetricSpec v2 autoscaling.
autoScalingBehaviorConfigure 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.
envSpecify 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.
- name: example1
value: simpleValue
- name: example2
name: secret-name
key: akey