Pulsar Functions support the following methods to run functions.
- Thread: Invoke functions in threads in Functions Worker.
- Process: Invoke functions in processes forked by Functions Worker.
- Kubernetes: Submit functions as Kubernetes StatefulSets by Functions Worker.
The differences of the thread and process modes are:
- Thread mode: when a function runs in thread mode, it runs on the same Java virtual machine (JVM) with Functions worker.
- Process mode: when a function runs in process mode, it runs on the same machine that Functions worker runs.
Configure thread runtime
It is easy to configure Thread runtime. In most cases, you do not need to configure anything. You can customize the thread group name with the following settings:
threadContainerFactory: threadGroupName: "Your Function Container Group"
Thread runtime is only supported in Java function.
Configure process runtime
When you enable Process runtime, you do not need to configure anything.
processContainerFactory: # the directory for storing the function logs logDirectory: # change the jar location only when you put the java instance jar in a different location javaInstanceJarLocation: # change the python instance location only when you put the python instance jar in a different location pythonInstanceLocation: # change the extra dependencies location: extraFunctionDependenciesDir:
Process runtime is supported in Java, Python, and Go functions.
Configure Kubernetes runtime
It is easy to configure Kubernetes runtime. You can just uncomment the settings of
kubernetesContainerFactory in the
functions_worker.yaml file. The following is an example.
kubernetesContainerFactory: # uri to kubernetes cluster, leave it to empty and it will use the kubernetes settings in function worker k8Uri: # the kubernetes namespace to run the function instances. it is `default`, if this setting is left to be empty jobNamespace: # the docker image to run function instance. by default it is `apachepulsar/pulsar` pulsarDockerImageName: # the root directory of pulsar home directory in `pulsarDockerImageName`. by default it is `/pulsar`. # if you are using your own built image in `pulsarDockerImageName`, you need to set this setting accordingly pulsarRootDir: # this setting only takes effects if `k8Uri` is set to null. if your function worker is running as a k8 pod, # setting this to true is let function worker to submit functions to the same k8s cluster as function worker # is running. setting this to false if your function worker is not running as a k8 pod. submittingInsidePod: false # setting the pulsar service url that pulsar function should use to connect to pulsar # if it is not set, it will use the pulsar service url configured in worker service pulsarServiceUrl: # setting the pulsar admin url that pulsar function should use to connect to pulsar # if it is not set, it will use the pulsar admin url configured in worker service pulsarAdminUrl: # the custom labels that function worker uses to select the nodes for pods customLabels: # the directory for dropping extra function dependencies # if it is not an absolute path, it is relative to `pulsarRootDir` extraFunctionDependenciesDir: # Additional memory padding added on top of the memory requested by the function per on a per instance basis percentMemoryPadding: 10
If you have already run a Pulsar cluster on Kubernetes, you can keep the settings unchanged at most of time.
However, if you enable RBAC on deploying your Pulsar cluster, make sure the service account you use for running Functions Workers (or brokers, if Functions Workers run along with brokers) have permissions on the following kubernetes APIs.
Otherwise, you will not be able to create any functions. The following is an example of error message.
22:04:27.696 [Timer-0] ERROR org.apache.pulsar.functions.runtime.KubernetesRuntimeFactory - Error while trying to fetch configmap example-pulsar-4qvmb5gur3c6fc9dih0x1xn8b-function-worker-config at namespace pulsar io.kubernetes.client.ApiException: Forbidden at io.kubernetes.client.ApiClient.handleResponse(ApiClient.java:882) ~[io.kubernetes-client-java-2.0.0.jar:?] at io.kubernetes.client.ApiClient.execute(ApiClient.java:798) ~[io.kubernetes-client-java-2.0.0.jar:?] at io.kubernetes.client.apis.CoreV1Api.readNamespacedConfigMapWithHttpInfo(CoreV1Api.java:23673) ~[io.kubernetes-client-java-api-2.0.0.jar:?] at io.kubernetes.client.apis.CoreV1Api.readNamespacedConfigMap(CoreV1Api.java:23655) ~[io.kubernetes-client-java-api-2.0.0.jar:?] at org.apache.pulsar.functions.runtime.KubernetesRuntimeFactory.fetchConfigMap(KubernetesRuntimeFactory.java:284) [org.apache.pulsar-pulsar-functions-runtime-2.4.0-42c3bf949.jar:2.4.0-42c3bf949] at org.apache.pulsar.functions.runtime.KubernetesRuntimeFactory$1.run(KubernetesRuntimeFactory.java:275) [org.apache.pulsar-pulsar-functions-runtime-2.4.0-42c3bf949.jar:2.4.0-42c3bf949] at java.util.TimerThread.mainLoop(Timer.java:555) [?:1.8.0_212] at java.util.TimerThread.run(Timer.java:505) [?:1.8.0_212]
If this happens, you need to grant the required permissions to the service account used for running Functions Workers. An example to grant permissions is shown below: a service account
functions-worker is granted with permissions to access Kubernetes resources
apiVersion: rbac.authorization.k8s.io/v1beta1 kind: ClusterRole metadata: name: functions-worker rules: - apiGroups: [""] resources: - services - configmaps - pods verbs: - '*' - apiGroups: - apps resources: - statefulsets verbs: - '*' apiVersion: v1 kind: ServiceAccount metadata: name: functions-worker apiVersion: rbac.authorization.k8s.io/v1beta1 kind: ClusterRoleBinding metadata: name: functions-worker roleRef: apiGroup: rbac.authorization.k8s.io kind: ClusterRole name: functions-worker subjects: - kind: ServiceAccount name: functions-worker