VPC 中的 AWS Lambda 有时无法访问互联网

我有部署到 VPC 的 Lambda。

此部署有以下配置：

• 专有网络 (192.168.0.0/16)
• 公共子网 A (192.168.32.0/20) 具有 NAT 网关和到 Internet 网关的路由 0.0.0.0/0
• 私有子网 A (192.168.48.0/20) 具有到 NAT 网关的路由 0.0.0.0/0
• 私有子网B (192.168.64.0/20)

Lambda 有自己的安全组和对“私有子网”和“私有子网 B”的引用

我有一个奇怪的问题：Lambda 有时无法访问互联网。第三方服务正常。

另一件奇怪的事情是，Lambda 从子网（192.168.48.0/20 和 192.168.64.0/20）获取 IP，如 127.0.0.1、169.254.76.13、169.254.79.1，而不是 IP。

Error:

Error: connect ETIMEDOUT x.x.x.x:443
at Object._errnoException (util.js:1022:11)
at _exceptionWithHostPort (util.js:1044:20)
at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1198:14)

Deployment schema:

这里是完整的 CloudFormation 模板：

    ---
AWSTemplateFormatVersion: '2010-09-09'
Description: 'Base Infrastructure'
Metadata:
  'AWS::CloudFormation::Interface':
    ParameterGroups:
    - Label:
        default: 'VPC Parameters'
      Parameters:
      - VpcId
      - InternetGatewayId
Parameters:
  VpcId:
    Type: String
  InternetGatewayId:
    Type: String
Resources:
  SubnetAPublic:
    Type: 'AWS::EC2::Subnet'
    Properties:
      AvailabilityZone: !Select [0, !GetAZs '']
      CidrBlock: !Sub '192.168.32.0/20'
      MapPublicIpOnLaunch: true
      VpcId: !Sub '${VpcId}'
  SubnetAPrivate:
    Type: 'AWS::EC2::Subnet'
    Properties:
      AvailabilityZone: !Select [0, !GetAZs '']
      CidrBlock: !Sub '192.168.48.0/20'
      VpcId: !Sub '${VpcId}'
  SubnetBPrivate:
    Type: 'AWS::EC2::Subnet'
    Properties:
      AvailabilityZone: !Select [1, !GetAZs '']
      CidrBlock: !Sub '192.168.64.0/20'
      VpcId: !Sub '${VpcId}'
  RouteTablePublic:
    Type: 'AWS::EC2::RouteTable'
    Properties:
      VpcId: !Sub '${VpcId}'
  RouteTablePrivate:
    Type: 'AWS::EC2::RouteTable'
    Properties:
      VpcId: !Sub '${VpcId}'
  RouteTableBPrivate:
    Type: 'AWS::EC2::RouteTable'
    Properties:
      VpcId: !Sub '${VpcId}'
  RouteTableAssociationAPublic:
    Type: 'AWS::EC2::SubnetRouteTableAssociation'
    Properties:
      SubnetId: !Ref SubnetAPublic
      RouteTableId: !Ref RouteTablePublic
  RouteTableAssociationAPrivate:
    Type: 'AWS::EC2::SubnetRouteTableAssociation'
    Properties:
      SubnetId: !Ref SubnetAPrivate
      RouteTableId: !Ref RouteTablePrivate
  RouteTableAssociationBPrivate:
    Type: 'AWS::EC2::SubnetRouteTableAssociation'
    Properties:
      SubnetId: !Ref SubnetBPrivate
      RouteTableId: !Ref RouteTableBPrivate
  EIP:
    Type: 'AWS::EC2::EIP'
    Properties:
      Domain: vpc
  NatGateway:
    Type: 'AWS::EC2::NatGateway'
    Properties:
      AllocationId: !GetAtt 'EIP.AllocationId'
      SubnetId: !Ref SubnetAPublic
  RouteTablePublicInternetRoute:
    Type: AWS::EC2::Route
    Properties:
      RouteTableId: !Ref RouteTablePrivate
      DestinationCidrBlock: '0.0.0.0/0'
      NatGatewayId: !Ref NatGateway
  RouteTablePublicInternetRoute2:
    Type: AWS::EC2::Route
    Properties:
      RouteTableId: !Ref RouteTablePublic
      DestinationCidrBlock: '0.0.0.0/0'
      GatewayId: !Sub '${InternetGatewayId}'
  ServerlessSecurityGroup:
    Type: AWS::EC2::SecurityGroup
    Properties:
      GroupDescription: SecurityGroup for Serverless Functions
      VpcId: !Sub '${VpcId}'
  ServerlessSecurityGroupIngress:
    Type: AWS::EC2::SecurityGroupIngress
    Properties:
      GroupId: !Ref ServerlessSecurityGroup
      IpProtocol: -1
      SourceSecurityGroupId: !Ref ServerlessSecurityGroup

有什么想法我做错了吗？

P.S.：我发现类似的问题AWS VPC Lambda 函数不断失去互联网访问权限 https://stackoverflow.com/questions/36581147/aws-vpc-lambda-function-keeps-losing-internet-access and 为什么VPC中的AWS lambda函数有时会超时，有时会正常工作？ https://stackoverflow.com/questions/51373609/why-aws-lambda-functions-in-a-vpc-sometimes-timeout-and-sometimes-work-fine

UPD

添加了路线，现在可以使用了

  RouteTableBPrivateInternetRoute:
    Type: AWS::EC2::Route
      Properties:
        RouteTableId: !Ref RouteTableBPrivate
        DestinationCidrBlock: '0.0.0.0/0'
        NatGatewayId: !Ref NatGateway

为了使在 VPC 内部运行的 AWS Lambda 函数能够访问 VPC 外部的资源（例如 Internet），它必须位于具有 NAT 网关的私有子网中。在您的实例中，私有子网 A 是唯一具有适当配置以允许 Lambda 函数访问 Internet 的子网。因此，您需要编辑 Lambda 函数的配置，使其仅在该子网中运行。