Developing a Python Job

Preparing the Environment

• An ECS named ecs-dgc has been created.
  

  In this example, the ECS uses the CentOS 8.0 64bit with ARM (40 GB) public image and the Python environment. You can log in to the ECS and run the python command to check the Python environment.

  

• You have enabled the DataArts Migration incremental package and created a CDM cluster named cdm-dlfpyhthon. The cluster provides an agent for the DataArts Factory module to communicate with the ECS.
• Ensure that the ECS can communicate with the CDM cluster, which depends on the following conditions:
  • If the CDM cluster and the ECS are in the same region, VPC, subnet, and security group, they can communicate with each other by default. If they are in the same VPC but in different subnets or security groups, you must configure routing rules and security group rules. For details about how to configure routing rules, see configuring routes. For details about how to configure security group rules, see configuring security group rules.
  • If the CDM cluster and the ECS are in different regions, a public network or a dedicated connection is required for enabling communication between the CDM cluster and the cloud service. If the Internet is used for communication, ensure that an EIP has been bound to the CDM cluster, the host where the data source is located can access the Internet, and the port has been enabled in the firewall rules.
  • The ECS and the CDM cluster belong to the same enterprise project. If they do not, you can modify the enterprise project of the workspace.

Constraints

• Python nodes support script parameters and job parameters.
• This section uses Python3 as an example.

Creating an ECS Data Connection

Before developing a Python script, you need to create a connection to the ECS.

1. Log in to the DataArts Studio console by following the instructions in Accessing the DataArts Studio Instance Console.
2. On the DataArts Studio console, locate a workspace and click Management Center.
3. On the displayed Manage Data Connections page, click Create Data Connection.
4. Configure parameters by referring to Table 1 and create a data connection named ecs.

   Table 1 Host Connection parameters

   Parameter	Mandatory	Description
   Data Connection Type	Yes	Host Connection is selected by default and cannot be changed.
   Name	Yes	Name of the data connection to create. Data connection names can contain a maximum of 100 characters. They can contain only letters, digits, underscores (_), and hyphens (-).
   Tag	No	Attribute of the data connection to create. Tags make management easier. NOTE: The tag name can contain only letters, digits, and underscores (_) and cannot start with an underscore (_) or contain more than 100 characters.
   Applicable Modules	Yes	Select the modules for which this connection is available. All modules are selected by default, which means this connection is available for all the modules that support the data source connected by this connection. For details about the data sources supported by each module, see Data Sources.
   Basic and Network Connectivity Configuration
   Host Address	Yes	IP address of the Linux host For details, see Viewing Details About an ECS.
   Agent	Yes	CDM cluster used as an agent. NOTE: If a CDM cluster functions as the agent for a data connection in Management Center, the cluster supports a maximum of 200 concurrent active threads. If multiple data connections share an agent, a maximum of 200 SQL, Shell, and Python scripts submitted through the connections can run concurrently. Excess tasks will be queued. You are advised to plan multiple agents based on the workload. When scheduling shell or Python scripts, the agent accesses the ECS. If shell and Python scripts are scheduled frequently, the ECS adds the private IP address of the agent to the blocklist. To ensure normal job scheduling, you are advised to use the root user of the ECS to add the private IP address bound to the agent (CDM cluster) to the /etc/hosts.allow file. For details about how to obtain the private IP address of the CDM cluster, see Viewing Basic Cluster Information and Modifying Cluster Configurations.
   Port	Yes	SSH port number of the host. By default, port 22 is used to log in to a Linux host. If the port number has been changed, you can obtain the new port number from the port field in the /etc/ssh/sshd_config file.
   KMS Key	Yes	KMS key used to encrypt and decrypt the authentication information for the data source
   Data Source Authentication and Other Function Configuration
   Username	Yes	Username for logging in to the host
   Login Mode	Yes	Mode for logging in to the host Key Pair Password
   Key Pair	Yes	This parameter is available only when Login Mode is set to Key Pair. If Key Pair is the login mode of the host, you need to obtain the private key file, upload it to OBS, and select an OBS path. NOTE: The uploaded private key must match the public key configured on the host. For details, see Application Scenarios for Using Key Pairs.
   Key Pair Password	Yes	If no password is set for the key pair, you do not need to set this parameter.
   Password	Yes	This parameter is available only when Login Mode is set to Password. If the login mode of the host is to use a password, enter a login password.
   Host Connection Description	No	Descriptive information about the host connection

   Figure 1 Creating a host connection
   
   

   The key parameters are as follows:

   • Host Address: Enter the IP address of the ECS.
   • Agent: Select the CDM cluster you have obtained from the DataArts Migration incremental package.

5. Click Test to test connectivity of the data connection. If the test fails, the data connection cannot be created.
6. After the test is successful, click OK to create the data connection.

Developing a Python Script

1. Choose DataArts Factory > Develop Script and create a Python script named python_test.
   Figure 2 Creating a Python script
   

2. Select a Python version and host connection, and set input parameters as needed.
   

   The parameters will be transferred to the Python script when the script is executed. The parameters are separated by spaces, for example, Microsoft Oracle. The parameters must be referenced by the Python script. Otherwise, the parameters are invalid.

3. Edit Python statements in the editor.
   This example defines a string template for saving company information and uses the template to output information about different companies.

   import sys
   Company_Name1=sys.argv[1]
   Company_Name2=sys.argv[2]
   template='No.:{:0>9s} \t CompanyName: {:s} \t Website: https://www.{:s}.com'
   context1=template.format('1',Company_Name1,Company_Name1.lower())
   context2=template.format('2',Company_Name2,Company_Name2.lower())
   print(context1)
   print(context2)

   

   • The script development area in Figure 3 is a temporary debugging area. After you close the script tab, the development area will be cleared.
   • Connection: Select the data connection created in Creating an ECS Data Connection.
   Figure 3 Editing the Python statements
   

4. Click Save and then Submit.
5. Click Execute to execute the Python statements.
6. View the script execution result.
   Figure 4 Viewing the script execution result
   

Referencing the Python Script in a Job

1. Create a job.
2. Select a Python node and configure the node properties.
   Select the created Python script and set the node parameters. Set Script Parameters.

   

   The parameters will be transferred to the Python statement when the statement is executed. The parameters are separated by spaces, for example, Microsoft Oracle. The parameters must be referenced by the Python statement. Otherwise, the parameters are invalid.

   Figure 5 Configuring properties of the Python node
   

3. Click Test and view the job running result.
   Figure 6 Checking the job execution result
   

4. Click Save. The job configuration is complete.
5. Click Submit. After a version is submitted, the job can be scheduled.