Shell

Overview

Shell task used to create a shell task type and execute a series of shell scripts. When the worker run the shell task, a temporary shell script is generated, and use the Linux user with the same name as the tenant executes the script.

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 to the canvas.

Task Parameter

• 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.
• Descriptive information: 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. You can select from drop-down or fill-in a number.
• Failed retry interval: The time interval for resubmitting the task after a failed task. You can select from drop-down or fill-in a number.
• 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.
• Script: Shell program developed by users.
• Resource: Refers to the list of resource files that called in the script, and upload or create files by the Resource Center file management.
• Custom parameters: It is a user-defined local parameter of Shell, 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

Simply Print

We make an example simulate from a common task which runs by one command. The example is to print one line in the log file, as shown in the following figure: “This is a demo of shell task”.

Custom Parameters

This example simulates a custom parameter task. We use parameters for reusing existing tasks as template or coping with the dynamic task. In this case, we declare a custom parameter named “param_key”, with the value “param_val”. Then we use echo to print the parameter “${param_key}” we just declared. After running this example, we would see “param_val” print in the log.