Deploying a Function to a VPC

Last updated: 2020-07-07 11:00:50

    Operation Scenarios

    Tencent Cloud SCF id deployed in the public network by default. This document describes how to enable SCF to access resources in the private network through VPC configuration, such as TencentDB, CVM, TencentDB for Redis, and CKafka, which helps ensure data and connection security.

    Notes

    When configuring a VPC, pay attention to the following points:

    • A function deployed in a VPC is isolated from the public network by default. If you want the function to have access to both private network and public network, you can do so in the following two ways:
      • Configure the public network access of SCF and make sure that the egress address for public network access is unique.
      • Add an NAT gateway through VPC. For more information, please see Configuring NAT in VPC.
    • Currently, functions cannot be connected with resources on the basic network.

    Prerequisites

    You have created a function.

    Directions

    Modifying network configuration

    1. Log in to the Serverless Cloud Function Console and click Function Service(https://console.cloud.tencent.com/scf/list) in the left sidebar.
    2. Select the region at the top of the page and click the name of the function to be configured.
    3. On the "Function Configuration" page, click Edit in the top-right corner.
    4. Set VPC to "Enable", and select the VPC and subnet you want to use.

    Using VPC

    After you configure the private network access for a function and start to use the VPC, the function will switch from the current independent network environment to the configured VPC. When the function starts, an IP address in your VPC subnet will be used as the IP address of the function runtime environment. In order to reduce the functions' usage of subnet IP addresses, running function instances will share a proxy pair and scale the proxy pair based on the network bandwidth utilization.

    After the function is started, you can use code and private IP address to access resources whose access entries are in the VPC, such as TencentDB for Redis, TDSQL, and CVM.
    The following is sample code to access TencentDB for Redis, where the IP address of the Redis instance in the VPC is 10.0.0.86.

    # -*- coding: utf8 -*-
    import redis
    def main_handler(event,context):
        r = redis.StrictRedis(host='10.0.0.86', port=6379, db=0,password="crs-i4kg86dg:abcd1234")
        print(r.set('foo', 'bar'))
        print(r.get('foo'))
        return r.get('foo')

    Name server configuration in VPC

    After configuring private network access for a function, if you want to use domain names to access your self-built services in the VPC, you usually need to use a custom name server to implement domain name resolution.
    In order to support the custom name server configuration in the SCF environment, you can implement the custom name server by configuring the OS_NAMESERVER environment variable as shown below:

    Environment Variable Name Value Rule Feature
    OS_NAMESERVER
    • It can be one or more IP addresses or domain names separated by ;.
    • A maximum of 5 custom name servers can be configured.
    Configures custom name server.

    Verifying configuration

    As shown in the following code, the configuration can be checked for effect by printing out the /etc/resolv.conf file.

    with open("/etc/resolv.conf") as f:
        print(f.readlines())

    Relevant Operations

    Viewing network configuration

    1. Log in to the Serverless Cloud Function Console and click Function Service(https://console.cloud.tencent.com/scf/list) in the left sidebar.
    2. Select a region at the top of the page and click the name of a function for which private network access has been configured to view the specific configuration through the corresponding network and subnet.

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