Creating a Flink Jar Job

Prerequisites

• When you use a Flink Jar job to access other external data sources, such as OpenTSDB, HBase, Kafka, GaussDB(DWS), RDS, CSS, CloudTable, DCS Redis, and DDS, you need to create a datasource connection to connect the job running queue to the external data source.
  • For details about the external data sources that can be accessed by Flink jobs, see Common Development Methods for DLI Cross-Source Analysis.
  • For how to create a datasource connection, see Configuring the Network Connection Between DLI and Data Sources (Enhanced Datasource Connection).

    On the Resources > Queue Management page, locate the queue you have created, click More in the Operation column, and select Test Address Connectivity to check if the network connection between the queue and the data source is normal. For details, see Testing Address Connectivity.

• To run a Flink Jar job, you need to build your custom application code into a JAR file and upload it to the OBS bucket that has already been created.
• Flink dependencies have been built in the DLI server and security hardening has been performed based on the open-source community version. To avoid dependency package compatibility issues or log output and dump issues, be careful to exclude the following files when packaging:
  • Built-in dependencies (or set the package dependency scope to provided in Maven or SBT)
  • Log configuration files (example, log4j.properties/logback.xml)
  • JAR package for log output implementation (example, log4j).

Precautions

Before creating jobs and submitting tasks, you are advised to enable CTS to record operations associated with DLI for later query, audit, and backtrack operations. To view the DLI operations that can be recorded by CTS, see Using CTS to Audit DLI.

For how to enable CTS and view trace details, see the Cloud Trace Service Getting Started.

Creating a Flink Jar Job

1. In the left navigation pane of the DLI management console, choose Job Management > Flink Jobs. The Flink Jobs page is displayed.
2. In the upper right corner of the Flink Jobs page, click Create Job.
   Figure 1 Creating a Flink Jar job
   

3. Specify job parameters.

   Table 1 Job configuration information

   Parameter	Description
   Type	Select Flink Jar.
   Name	Job name. Enter 1 to 57 characters. Only letters, numbers, hyphens (-), and underscores (_) are allowed. NOTE: The job name must be globally unique.
   Description	Description of a job. It can be up to 512 characters long.
   Tags	Tags used to identify cloud resources. A tag includes the tag key and tag value. If you want to use the same tag to identify multiple cloud resources, that is, to select the same tag from the drop-down list box for all services, you are advised to create predefined tags on the Tag Management Service (TMS). If your organization has configured tag policies for DLI, add tags to resources based on the policies. If a tag does not comply with the tag policies, resource creation may fail. Contact your organization administrator to learn more about tag policies. For details, see Tag Management Service User Guide. NOTE: A maximum of 20 tags can be added. Only one tag value can be added to a tag key. The key name in each resource must be unique. Tag key: Enter a tag key name in the text box. NOTE: A tag key can contain a maximum of 128 characters. Only letters, numbers, spaces, and special characters (_.:=+-@) are allowed, but the value cannot start or end with a space or start with _sys_. Tag value: Enter a tag value in the text box. NOTE: A tag value can contain a maximum of 255 characters. Only letters, numbers, spaces, and special characters (_.:=+-@) are allowed. The value cannot start or end with a space.

4. Click OK to enter the editing page.
5. Select a queue.
6. Configuring Flink Jar Job parameters
   Figure 2 Configuring Flink Jar Job parameters
   

   Table 2 Parameters

   Parameter	Description
   Queue	Select a queue where you want to run your job.
   Application	Select a Jar job package. There are the following ways to manage JAR files: Upload packages to OBS: Upload Jar packages to an OBS bucket in advance and select the corresponding OBS path. Upload packages to DLI: Upload JAR files to an OBS bucket in advance and create a package on the Data Management > Package Management page of the DLI management console. For details, see Creating a DLI Package. For Flink 1.15 or later, you can only select a package from OBS, instead of DLI.
   Main Class	The name of the JAR package to be loaded, for example, KafkaMessageStreaming. Default: Specified based on the Manifest file in the JAR package. Manually assign: You must enter the class name and confirm the class arguments (separated by spaces). NOTE: When a class belongs to a package, the main class path must contain the complete package path, for example, packagePath.KafkaMessageStreaming.
   Class Arguments	List of arguments of a specified class. The arguments are separated by spaces. Flink parameters support replacement of non-sensitive global variables. For example, if you add the global variable windowsize in Global Configuration > Global Variables, you can add the -windowsSize {{windowsize}} parameter for the Flink Jar job.
   JAR Package Dependencies	Select a user-defined package dependency. The dependent program packages are stored in the classpath directory of the cluster. There are the following ways to manage JAR files: Upload packages to OBS: Upload Jar packages to an OBS bucket in advance and select the corresponding OBS path. Upload packages to DLI: Upload JAR files to an OBS bucket in advance and create a package on the Data Management > Package Management page of the DLI management console. For details, see Creating a DLI Package. For Flink 1.15 or later, you can only select a package from OBS, instead of DLI. When creating a JAR file for a Flink Jar job, you do not need to upload existing built-in dependency packages to avoid package information conflicts. For details about built-in dependency packages, see DLI Built-in Dependencies.
   Other Dependencies	User-defined dependency files. Other dependency files need to be referenced in the code. There are the following ways to manage dependency files: Upload packages to OBS: Upload dependency files to an OBS bucket in advance and select the corresponding OBS path. Upload packages to DLI: Upload dependency files to an OBS bucket in advance and create a package on the Data Management > Package Management page of the DLI management console. For details, see Creating a DLI Package. For Flink 1.15 or later, you can only select a package from OBS, instead of DLI. You can add the following command to the application to access the corresponding dependency file. In the command, fileName indicates the name of the file to be accessed, and ClassName indicates the name of the class that needs to access the file. ClassName.class.getClassLoader().getResource("userData/fileName")
   Job Type	This parameter is displayed when the queue type is CCE. Basic Image: Select the image name and image version. Image set on the Software Repository for Container (SWR) console. For details, see Using a Custom Image to Enhance the Job Running Environment.
   Flink Version	Set Queue before setting this parameter. NOTE: You are not advised to use Flink of different versions for a long time. Doing so can lead to code incompatibility, which can negatively impact job execution efficiency. Doing so may result in job execution failures due to conflicts in dependencies. Jobs rely on specific versions of libraries or components.
   Agency	If you choose Flink 1.15 to execute your job, you can create a custom agency to allow DLI to access other services.
   Runtime Configuration	User-defined optimization parameters. The parameter format is key=value. Flink optimization parameters support replacement non-sensitive global variable. For example, if you create global variable phase in Global Configuration > Global Variables, optimization parameter table.optimizer.agg-phase.strategy={{phase}} can be added to the Flink Jar job. Flink 1.15 supports minimal submission of Flink Jar jobs. Enable this by configuring flink.dli.job.jar.minimize-submission.enabled=true in the runtime optimization parameters. NOTE: Minimal submission means Flink only submits the necessary job dependencies, not the entire Flink environment. By setting the scope of non-Connector Flink dependencies (starting with flink-) and third-party libraries (like Hadoop, Hive, Hudi, and MySQL-CDC) to provided, you ensure these dependencies are excluded from the Jar job, avoiding conflicts with Flink core dependencies. Only Flink 1.15 supports minimal submission of Flink Jar jobs. For Flink-related dependencies, use the provided scope by adding <scope>provided</scope> in the dependencies, especially for non-Connector dependencies under the org.apache.flink group starting with flink-. For dependencies related to Hadoop, Hive, Hudi, and MySQL-CDC, also use the provided scope by adding <scope>provided</scope> in the dependencies. In the Flink source code, only methods marked with @Public or @PublicEvolving are intended for user invocation. DLI guarantees compatibility with these methods.

7. Set compute resource specification parameters.
   Figure 3 Configuring job parameters
   

   Table 3 Parameters

   Parameter	Description
   CUs	One CU consists of one vCPU and 4 GB of memory. The number of CUs ranges from 2 to 10000.
   Job Manager CUs	Number of CUs for the job management unit.
   Parallelism	Number of tasks concurrently executed by each operator in a job. NOTE: The value must be less than or equal to four times the number of compute units (CUs minus the number of job manager CUs). Set this parameter to a value greater than that configured in the code to avoid job submission failures.
   Task Manager Config	Whether Task Manager resource parameters are set If this option is selected, you need to set the following parameters: CU(s) per TM: Number of resources occupied by each Task Manager. Slot(s) per TM: Number of slots contained in each Task Manager. If not selected, the system automatically uses the default values. CU(s) per TM: The default value is 1. Slot(s) per TM: The default value is (Parallelism x CU(s) per TM)/(CUs – Job Manager CUs).
   Save Job Log	Whether to save the job running logs to the OBS bucket. If you select this parameter, you also need to set OBS Bucket. CAUTION: You are advised to select this parameter. Otherwise, no run log is generated after the job is executed. If the job is abnormal, the run log cannot be obtained for fault locating.
   Enable Checkpointing	Checkpoints are used to periodically save the job state. Enabling checkpointing allows for the quick recovery of a specific job state in case of system failure. There are two ways to enable checkpointing in DLI: Configure checkpoint-related parameters in the job code, suitable for Flink 1.15 or earlier. Enable checkpointing on the Jar job configuration page of the DLI management console, suitable for Flink 1.15 or later. For Flink 1.15, do not configure checkpoint-related parameters both in the job code and the Jar job configuration page. The configurations in the job code have higher priority. Duplicate configurations may lead to the use of incorrect checkpoint paths during abnormal restarts, causing recovery failures or data inconsistencies. After selecting Enable Checkpointing, set the following parameters to enable checkpointing: Checkpoint Interval: The interval between checkpoints, in seconds. Checkpoint Mode: Select a mode for checkpoints. The options are: At least once: Events are processed at least once. Exactly once: Events are processed exactly once. CAUTION: After selecting Enable Checkpointing, you need to set OBS Bucket to save the checkpoint information. The default checkpoint save path is Bucket name/jobs/checkpoint/Directory with job ID prefix. Once checkpointing is enabled, do not set checkpoint parameters in the job code, as the parameters configured in the job code have a higher priority than those configured on the job configuration page. Duplicate configurations may cause the job to use incorrect checkpoint paths during abnormal restarts, resulting in recovery failures or data inconsistencies. After enabling checkpointing, if Auto Restart on Exception and Restore Job from Checkpoint are both selected, you do not need to set Checkpoint Path. The system will automatically determine the path based on the Enable Checkpointing configuration.
   OBS Bucket	This parameter is mandatory when you select Save Job Log or Enable Checkpointing. Select an OBS bucket to store job logs. If the OBS bucket you select is not authorized, click Authorize.
   Alarm on Job Exception	Whether to notify users of any job exceptions, such as running exceptions or arrears, via SMS or email. If this option is selected, you need to set the following parameters: SMN Topic Select a custom SMN topic. For how to create a custom SMN topic, see Creating a Topic.
   Auto Restart upon Exception	Whether automatic restart is enabled. If enabled, jobs will be automatically restarted and restored when exceptions occur. If this option is selected, you need to set the following parameters: Max. Retry Attempts: maximum number of retries upon an exception. The unit is times/hour. Unlimited: The number of retries is unlimited. Limited: The number of retries is user-defined. Restore Job from Checkpoint: Restore the job from the saved checkpoint. If you select this parameter, you need to set Checkpoint Path. Checkpoint Path: Select the checkpoint save path. This path must match that configured in the application package. Each job must have a unique checkpoint path, or, you will not be able to obtain the checkpoint. NOTE: If you also select Enable Checkpointing, you do not need to set Checkpoint Path. The system will automatically determine the path based on the Enable Checkpointing configuration. If you do not select Enable Checkpointing, you need to set Checkpoint Path.

8. Click Save on the upper right of the page.
9. Click Start in the upper right corner. On the displayed Start Flink Job page, confirm the job specifications and the price, and click Start Now to start the job. After the job is started, the system automatically switches to the Flink Jobs page, and the created job is displayed in the job list. You can view the job status in the Status column.
   • Once a job is successfully submitted, its status changes from Submitting to Running. After the execution is complete, the status changes to Completed.
   • If the job status is Submission failed or Running exception, the job fails to submit or run. In this case, you can hover over the status icon in the Status column of the job list to view the error details. You can click to copy these details. Rectify the fault based on the error information and resubmit the job.