In Function Compute, you can use a function to call database APIs to insert or query data. In most cases, instance status is not shared among different execution environments in Function Compute. You can persist structured data in a database to share instance status. This topic uses Python 3 as an example to describe how to use Serverless Devs to deploy a function to access an ApsaraDB RDS for PostgreSQL database.

Prerequisites

  • Create an ApsaraDB RDS for PostgreSQL instance
    Notice
    • Make sure that the database instance you created is in the same region as the function that needs to access the database instance.

    • We recommend that you create the database instance in a zone that supports Function Compute.

      If your resources are not deployed in the zones shown in the following list, create a vSwitch in your virtual private cloud (VPC). The vSwitch must be in the same zone as Function Compute. Also, you must specify the vSwitch ID when you configure the VPC for Function Compute. vSwitches in the same VPC can communicate with each other over the private network. Therefore, Function Compute can use the vSwitch to access resources in the VPC that reside in other zones. For more information, see How can I resolve the "vSwitch is in unsupported zone" error?.

      Region Region ID Zones supported by Function Compute
      China (Hangzhou) cn-hangzhou cn-hangzhou-f, cn-hangzhou-g, cn-hangzhou-h
      China (Shanghai) cn-shanghai cn-shanghai-b, cn-shanghai-e, cn-shanghai-g, cn-shanghai-f
      China (Qingdao) cn-qingdao cn-qingdao-c
      China (Beijing) cn-beijing cn-beijing-h, cn-beijing-c, cn-beijing-e, cn-beijing-f
      China (Zhangjiakou) cn-zhangjiakou cn-zhangjiakou-b, cn-zhangjiakou-a
      China (Hohhot) cn-huhehaote cn-huhehaote-a, cn-huhehaote-b
      China (Shenzhen) cn-shenzhen cn-shenzhen-e, cn-shenzhen-d
      China (Chengdu) cn-chengdu cn-chengdu-a, cn-chengdu-b
      China (Hong Kong) cn-hongkong cn-hongkong-c
      Singapore (Singapore) ap-southeast-1 ap-southeast-1a, ap-southeast-1b
      Australia (Sydney) ap-southeast-2 ap-southeast-2a, ap-southeast-2b
      Malaysia (Kuala Lumpur) ap-southeast-3 ap-southeast-3a
      Indonesia (Jakarta) ap-southeast-5 ap-southeast-5a, ap-southeast-5b
      Japan (Tokyo) ap-northeast-1 ap-northeast-1b, ap-northeast-1a
      UK (London) eu-west-1 eu-west-1a
      Germany (Frankfurt) eu-central-1 u-central-a, eu-central-1a, eu-central-1b
      US (Silicon Valley) us-west-1 us-west-1a, us-west-1b
      US (Virginia) us-east-1 us-east-1b, us-east-1a
      India (Mumbai) ap-south-1 ap-south-1a, ap-south-1b
  • Create a table that is named COMPANY and insert the ID, NAME, AGE, ADDRESS, and SALARY columns into the table.

    In this example, s init inserts a data record into a database table named COMPANY. The schema of the table contains the ID, NAME, AGE, ADDRESS, and SALARY columns. You must create the table and the columns in advance.

  • Install Serverless Devs and Docker.
  • Configure Serverless Devs
  • Create a security group

    Create a default security group in the VPC where the database instance is deployed. If you want to use an existing security group, make sure that the security group allows outbound traffic to the ports and private CIDR blocks of the database instance. By default, the security group allows all outbound traffic.

Configure the whitelist for the database

In ApsaraDB RDS for PostgreSQL, you can add IP addresses to the whitelist or specify security groups to access the database. We recommend that you add IP addresses to the whitelist to access the database.

  1. Log on to the ApsaraDB RDS console.
  2. In the left-side navigation pane, click Instances.
  3. In the top navigation bar, select a region.
  4. On the database instances page, find the instance that you want to manage and click the instance ID.
  5. In the left-side navigation pane, click Data Security.
  6. On the Whitelist Settings tab that appears, find the default whitelist group and click Modify.
  7. In the Edit Whitelist dialog box, configure IP Addresses and click OK.
    Notice The IP address that you specify must belong to a CIDR block of the vSwitch that you added when you configured the network for Function Compute.

Deploy and invoke functions

  1. Initialize a project.
    s init start-fc-postgresql-python -d start-fc-postgresql-python
  2. Access the project.
    cd start-fc-postgresql-python
  3. Edit the s.yaml file.

    Example:

    edition: 1.0.0         
    name: fcDeployApp       
    access: "default"  
    
    services:
      fc-db-postgresql-python: 
        component: devsapp/fc  
        props: 
          region: cn-hangzhou
          service:
            name: fc-db-demo
            description: 'demo for fc visit db'
            internetAccess: true
            vpcConfig:
              vpcId: vpc-bp1hcg467ekqsv0zr**** # The ID of the VPC where the database instance resides. 
              securityGroupId: sg-bp1j6knvj40yjn0g**** # The ID of the security group. 
              vswitchIds:
                - vsw-bp1lgecrqfslgji9b**** # Make sure that the CIDR block of the vSwitch is added to the whitelist of the database instance. 
          function:
            name: postgresql
            description: visit postgresql
            runtime: python3
            codeUri: ./code
            handler: index.handler
            memorySize: 256
            timeout: 30
            environmentVariables:
              DATABASE: post**** # The name of the database. 
              HOST: pgm-bp1n6g63x0xdb7oy16****.pg.rds.aliyuncs.com # The endpoint of the database. 
              PORT: 19** # The port number of the database. 
              USER: ni**** # The name of the database user. 
              PASSWORD: Hang**** # The password of the database user. 
  4. Run the following command to build the project.
    s build --use-docker
  5. Run the following command to deploy the project.
    s deploy -y
  6. Run the following command to invoke a function.
    s invoke -e "{}"

    The expected command output is as follows:

    [2021-09-23T11:03:17.792] [INFO ] [S-CLI] - Start ...
    ========= FC invoke Logs begin =========
    FC Invoke Start RequestId: 7e6657d4-504a-4faa-8f59-5464df73aa65
    FC Invoke End RequestId: 7e6657d4-504a-4faa-8f59-5464df73aa65
    
    Duration: 101.87 ms, Billed Duration: 102 ms, Memory Size: 256 MB, Max Memory Used: 35.08 MB
    ========= FC invoke Logs end =========
    
    FC Invoke Result:
    successfully
    
    
    End of method: invoke

What to do next

Collection of cases to access the database instance by using Function Compute