Function Compute:Access a Tair (Redis OSS-compatible) database

Before you start

Create an Redis instance

Procedure

1. Install Serverless Devs and Docker and configure the AccessKey information.

   For more information, see Install Serverless Devs and dependencies and Configure Serverless Devs.

2. Run the following command to initialize your project.

   sudo s init

   In the CLI, specify Alibaba Cloud as the vendor, specify the quick start mode, and select a built-in Python runtime. Configure the project name and the region where the project is deployed. In this example, the start-fc-redis-python project is deployed in the China (Hangzhou) region.

3. Run the following command to go to the project directory:

   cd start-fc-redis-python

4. Modify the directory file based on your own business requirements.

   • Edit the s.yaml file. Example:

     edition: 3.0.0
     name: hello-world-app
     access: "default"
     
     vars: # The global variables.
       region: "cn-hangzhou"
     
     resources:
       hello_world:
         component: fc3 # The component name.
         # actions:       # The custom execution logic. For more information about actions, visit https://docs.serverless-devs.com/serverless-devs/yaml#%E8%A1%8C%E4%B8%BA%E6%8F%8F%E8%BF%B0actions.
         props:
           region: ${vars.region}              # For information about how to use variables, visit https://docs.serverless-devs.com/serverless-devs/yaml#%E5%8F%98%E9%87%8F%E8%B5%8B%E5%80%BC.
           functionName: "start-python-xbk4"
           description: 'hello world by serverless devs'
           runtime: "python3.9"
           code: ./code
           handler: index.handler
           memorySize: 128
           timeout: 30
           internetAccess: true
           vpcConfig:
            vpcId: vpc-bp11y195luy47h8cm**** # The ID of the VPC in which the database instance resides.
            securityGroupId: sg-bp1el3hto8hhkdup**** # The ID of the security group.
            vSwitchIds: 
             - vsw-bp18vwna9x79koh3q**** # Make sure that the CIDR block of the vSwitch is added to the whitelist of the database instance. 
         environmentVariables:
          REDIS_HOST: r-bp17w15ohdk7****.redis.rds.aliyuncs.com # The private endpoint of the database instance. 
          REDIS_PASSWORD: 15**** # The password of the database instance. 
          REDIS_PORT: 6379 # The private port of the database instance.

     Important

     Make sure that the CIDR block of the vSwitch that you configure for the function is added to the whitelist of the database instance. For more information, see Configure an IP address whitelist for the database.

   • Edit the index.py code file. The following code snippet provides an example. The code logic is to read the value of the counter key from Redis, increase the value by 1, and then write the new value back to Redis.

     # -*- coding: utf-8 -*-
     import os
     import redis
     
     conn_pool = None
     
     
     def initializer(context):
         global conn_pool
         conn_pool = redis.ConnectionPool(
             host=os.environ['REDIS_HOST'], password=os.environ['REDIS_PASSWORD'],
             port=os.environ['REDIS_PORT'], db=1, decode_responses=True)
     
     
     def handler(event, context):
         global conn_pool
         r = redis.Redis(connection_pool=conn_pool)
     
         counter = r.get('counter')
     
         if counter is None:
             counter = 0
         else:
             counter = int(counter)
     
         print('counter: ' + str(counter))
     
         r.set('counter', str(counter + 1))
         return counter
     

5. Run the following command to build the project.

   sudo s build --use-docker

6. Run the following command to deploy the project.

   sudo s deploy -y

7. Run the following command to invoke the function.

   sudo s invoke -e "{}"

   The following code snippet shows the expected output. The value in the returned result increases from 0, which indicates that the value of the counter key is successfully read from Redis.

   [2021-09-14T17:08:50.875] [INFO ] [S-CLI] - Start ...
   ========= FC invoke Logs begin =========
   FC Initialize Start RequestId: ccd73383-048d-4c8d-834e-93da59b86a21
   FC Initialize End RequestId: ccd73383-048d-4c8d-834e-93da59b86a21
   FC Invoke Start RequestId: eccafc0a-493e-4f3e-9afa-45c0b84a2c0f
   counter: 0
   FC Invoke End RequestId: eccafc0a-493e-4f3e-9afa-45c0b84a2c0f
   
   Duration: 27.51 ms, Billed Duration: 28 ms, Memory Size: 256 MB, Max Memory Used: 34.05 MB
   ========= FC invoke Logs end =========
   
   FC Invoke Result:
   0
   
   
   End of method: invoke

Configure an IP address whitelist for the database

1. Log on to the console.

2. In the top navigation bar, select the region in which the instance is deployed.

3. On the Instances page, find the instance and click its ID.

4. In the left-side navigation pane of the instance details page, click Whitelist Settings. On the Whitelist Settings tab, find the whitelist that you want to modify and click Modify in the Actions column.

5. In the Modify Whitelist panel, enter the CIDR block of the vSwitch to which the instance is bound in the Whitelist field and click OK.

More information