How Does FunctionGraph Resolve a Private DNS Domain Name?

Resolving a Private DNS Domain Name

Ensure that a VPC and private DNS domain name have been created before performing the following steps:

1. Associate a VPC with the private domain name and add record sets.
   Log in to the DNS console and associate a VPC with the private domain name.

   Figure 1 Associating a VPC with the private domain name
   
   Click the domain name, and add a type A record set.

   Figure 2 Adding a record set
   

2. Create a function.

   Create a function whose runtime is Python 2.7. The following is sample code.

   # -*- coding:utf-8 -*-
   import json
   import os
   def handler(event, context):
        os.system("curl -iv www.test.com")

3. Configure an agency with DNS and VPC permissions for the function.

   On the IAM console, create an agency with DNS ReadOnlyAccess and VPC Administrator permissions for FunctionGraph.

   Figure 3 Creating an agency with DNS and VPC permissions
   
   

   You need to configure the permission to read DNS resource data because the function needs to obtain such data when parsing a domain name. Otherwise, the following error message is displayed, indicating that the DNS resource data failed to be obtained.

   2020/08/20 10:37:12 GMT+08:00  Start invoke request 'a2f105b4-2e72-4fda-94a5-86d3837e961d', version: latest
   [GET /v2/zones/{zone_id}/recordsets] failed, response: {"code":"DNS.1802","message":"Policy doesn't allow dns:recordset:list to be performed."}
   2020/08/20 10:37:13 GMT+08:00  Finish invoke request 'a2f105b4-2e72-4fda-94a5-86d3837e961d', duration: 1030.072ms, billing duration: 1100ms, memory used: 77.039MB.

4. Configure the function.

   On the details page of the function created in 2, click the Configuration tab and configure the following settings:

   1. For Permissions, select the agency created in 3.
   2. Enable VPC access and select the created VPC, subnet, and domain name. For details, see Figure 4.
   Figure 4 Configuring the function
   

5. Check the execution result.

   Then all configured IPv4 domain names can be parsed.

   Figure 5 Executing the function
   

Changes to the IP addresses corresponding to the VPC domain names you configure will take effect in 10 minutes.