Auto Scaling:Use Alibaba Cloud SDK for Python to execute rolling update tasks

Step 1: Install Alibaba Cloud SDK for Python

1. Run the following command to check the version of Python:

   python --version

   If the version of Python is returned, Python is installed. The following figure shows a sample command output.

2. Run the following command to install the SDK core library:

   pip install aliyun-python-sdk-core

3. Run the following command to install the Alibaba Cloud SDK Credentials tool.

   pip install alibabacloud_credentials

   Note

   You can configure the Alibaba Cloud Credentials tool by specifying the following environment variables: ALIBABA_CLOUD_ACCESS_KEY_ID and ALIBABA_CLOUD_ACCESS_KEY_SECRET. This allows you to access Alibaba Cloud OpenAPI Explorer without using a hard-coded plaintext AccessKey pair. For more information, see Configure environment variables.

4. Run the following command to install OOS SDK for Python:

   pip install aliyun-python-sdk-oos

Step 2: Execute a rolling update task

Sample code is provided in this step to demonstrate how to execute a script on ECS instances.

1. Create a Python script and enter the code to execute the rolling update task.

   For information about the OOS template parameters in the code, see OOS template parameters. Sample code:

   # -*- coding: UTF-8 -*-
   
   from aliyunsdkcore.client import AcsClient
   from alibabacloud_credentials.client import Client as CredClient
   from aliyunsdkoos.request.v20190601 import StartExecutionRequest
   import json
   cred=CredClient()
   accesskeyid = cred.get_access_key_id()
   accesskeysecret = cred.get_access_key_secret()
   # Create an AcsClient instance.
   client = AcsClient(accesskeyid, accesskeysecret)
   
   # Create a request and set the JSON data format.
   request = StartExecutionRequest.StartExecutionRequest()
   request.set_accept_format('json')
   
   # Replace the template name based on the selected update method.
   request.set_TemplateName("ACS-ESS-RollingUpdateByRunCommandInScalingGroup")
   
   # Associate a rolling update task with a scaling group to query the task execution status in the scaling group.
   request.set_Tags("{\"scaling_group\":\"asg-xxxxxxxx\"}")
   
   # Replace parameters based on the selected template.
   parameters = {"invokeType": "invoke",
                 "scalingGroupId": "asg-xxxxxxxxx",
                 "commandType": "RunShellScript",
                 "invokeScript": "df -h\nifconfig",
                 "rollbackScript": "df -h\nifconfig",
                 "OOSAssumeRole": "",
                 "exitProcess": [
                     "ScaleIn",
                     "ScaleOut",
                     "HealthCheck",
                     "AlarmNotification",
                     "ScheduledAction"
                 ],
                 "enterProcess": [
                     "ScaleIn",
                     "ScaleOut",
                     "HealthCheck",
                     "AlarmNotification",
                     "ScheduledAction"
                 ],
                 "batchNumber": 2,
                 "batchPauseOption": "Automatic"}
   
   request.set_Parameters(json.dumps(parameters))
   
   # Initiate the API request and obtain the response.
   response = client.do_action_with_exception(request)
   print(response)

2. Execute the Python script and check the command output.

   You can find information such as the execution ID of the rolling update task in the command output. The following figure shows a sample command output.

   Note

   To execute a rollback task, you must enter the execution ID of the source rolling update task.

   

(Optional) Execute a rollback task

If exceptions occur during rolling update tasks or if you want to use previous configurations after rolling upgrade tasks are executed, you can execute rollback tasks to restore the configurations of the ECS instances. Sample code is provided in this section to demonstrate how to roll back rolling update tasks that have been executed.

1. Create a Python script and enter the code to execute the rollback task.

   For information about the OOS template parameters in the code, see OOS template parameters. Sample code:

   # -*- coding: UTF-8 -*-
   
   from aliyunsdkcore.client import AcsClient
   from alibabacloud_credentials.client import Client as CredClient
   from aliyunsdkoos.request.v20190601 import StartExecutionRequest
   import json
   cred=CredClient()
   accesskeyid = cred.get_access_key_id()
   accesskeysecret = cred.get_access_key_secret()
   # Create an AcsClient instance.
   client = AcsClient(accesskeyid, accesskeysecret)
   
   # Create a request and set the JSON data format.
   request = StartExecutionRequest.StartExecutionRequest()
   request.set_accept_format('json')
   
   # Replace the template name based on the selected update method.
   request.set_TemplateName("ACS-ESS-RollingUpdateByRunCommandInScalingGroup")
   
   # Associate a rolling update task with a scaling group to query the task execution status in the scaling group.
   request.set_Tags("{\"scaling_group\":\"asg-xxxxxxxxxx\"}")
   
   # Parameters of the rollback operation
   parameters = {"invokeType": "rollback",
                 "scalingGroupId": "asg-xxxxxxxxx",
                 "commandType": "RunShellScript",
                 "rollbackScript": "df -h\nifconfig",
                 "OOSAssumeRole": "",
                 "sourceExecutionId": "exec-xxxxxxxx",
                 "batchNumber": 2,
                 "batchPauseOption": "Automatic"}
   
   request.set_Parameters(json.dumps(parameters))
   
   # Initiate the API request and obtain the response.
   response = client.do_action_with_exception(request)
   print(response)

2. Execute the Python script and check the command output.

   The following figure shows a sample command output.

OOS template parameters