Flink Node

Flink Node

Overview

Flink task type, used to execute Flink programs. For Flink nodes:

When the program type is Java, Scala or Python, the worker submits the task flink run using the Flink command. See flink cli for more details.
When the program type is SQL, the worker submit tasks using sql-client.sh. See flink sql client for more details.

Create Task

Click Project Management -> Project Name -> Workflow Definition, and click the Create Workflow button to enter the DAG editing page.
Drag from the toolbar task node to canvas.

Task Parameters

Parameter	Description
Node name	The node name in a workflow definition is unique.
Run flag	Identifies whether this node schedules normally, if it does not need to execute, select the `prohibition execution`.
Description	Describe the function of the node.
Task priority	When the number of worker threads is insufficient, execute in the order of priority from high to low, and tasks with the same priority will execute in a first-in first-out order.
Worker grouping	Assign tasks to the machines of the worker group to execute. If `Default` is selected, randomly select a worker machine for execution.
Environment Name	Configure the environment name in which run the script.
Times of failed retry attempts	The number of times the task failed to resubmit.
Failed retry interval	The time interval (unit minute) for resubmitting the task after a failed task.
Delayed execution time	The time (unit minute) that a task delays in execution.
Timeout alarm	Check the timeout alarm and timeout failure. When the task runs exceed the “timeout”, an alarm email will send and the task execution will fail.
Program type	Support Java, Scala, Python and SQL four languages.
Class of main function	The full path of Main Class, the entry point of the Flink program.
Main jar package	The jar package of the Flink program (upload by Resource Center).
Deployment mode	Support 3 deployment modes: cluster, local and application (Flink 1.11 and later. See also Run an application in Application Mode).
Initialization script	Script file to initialize session context.
Script	The sql script file developed by the user that should be executed.
Flink version	Select version according to the execution environment.
Task name	Flink task name.
JobManager memory size	Used to set the size of jobManager memories, which can be set according to the actual production environment.
Number of slots	Used to set the number of slots, which can be set according to the actual production environment.
TaskManager memory size	Used to set the size of taskManager memories, which can be set according to the actual production environment.
Number of TaskManager	Used to set the number of taskManagers, which can be set according to the actual production environment.
Parallelism	Used to set the degree of parallelism for executing Flink tasks.
Main program parameters	Set the input parameters for the Flink program and support the substitution of custom parameter variables.
Optional parameters	Support `—jar`, `—files`,`—archives`, `—conf` format.
Resource	Appoint resource files in the `Resource` if parameters refer to them.
Custom parameter	It is a local user-defined parameter for Flink, and will replace the content with `${variable}` in the script.
Predecessor task	Selecting a predecessor task for the current task, will set the selected predecessor task as upstream of the current task.

Task Example

Execute the WordCount Program

This is a common introductory case in the big data ecosystem, which often apply to computational frameworks such as MapReduce, Flink and Spark. The main purpose is to count the number of identical words in the input text. (Flink’s releases attach this example job)

Configure the flink environment in DolphinScheduler

If you are using the flink task type in a production environment, it is necessary to configure the required environment first. The following is the configuration file: bin/env/dolphinscheduler_env.sh.

Upload the Main Package

When using the Flink task node, you need to upload the jar package to the Resource Center for the execution, refer to the resource center.

After finish the Resource Centre configuration, upload the required target files directly by dragging and dropping.

Configure Flink Nodes

Configure the required content according to the parameter descriptions above.

Execute the FlinkSQL Program

Configure the required content according to the parameter descriptions above.

Note

JAVA and Scala only used for identification, there is no difference. If use Python to develop Flink, there is no class of the main function and the rest is the same.
Use SQL to execute Flink SQL tasks, currently only Flink 1.13 and above are supported.