AWS Cloudformation属性SubnetIds的值必须是String类型的List &g

Question

我正在捆绑这个云形成堆栈，但是当创建到达DBSubnetGroup时，它会失败，消息是:属性SubnetIds的值必须是字符串类型的列表。谢谢你的帮助。除了DBSubnetGroup之外，其他都很正常。

AWSTemplateFormatVersion: 2010-09-09
Description: My First CloudFormation Template
Resources:
MyVPC:
Type: AWS::EC2::VPC
Properties:
CidrBlock: 10.1.0.0/16
EnableDnsHostnames: true
EnableDnsSupport: true
InstanceTenancy: default
Tags:
- Key: Name
Value: VPC for Activity Number 1 
MySubnet:
Type: AWS::EC2::Subnet
Properties:
VpcId: !Ref MyVPC
CidrBlock: 10.1.1.0/24
MapPublicIpOnLaunch: true
AvailabilityZone: "us-east-1c"
Tags:
- Key: Name
Value: Public Subnet 
MySubnetA:
Type: AWS::EC2::Subnet
Properties:
VpcId: !Ref MyVPC
CidrBlock: 10.1.2.0/24
MapPublicIpOnLaunch: true
AvailabilityZone: "us-east-1a"
Tags:
- Key: Name
Value: Public Subnet  A
MySubnetB:
Type: AWS::EC2::Subnet
Properties:
VpcId: !Ref MyVPC
CidrBlock: 10.1.3.0/24
MapPublicIpOnLaunch: true
AvailabilityZone: "us-east-1b"
Tags:
- Key: Name
Value: Public Subnet B      

这就是创建失败的开始:

DBSubnetGroup:
Type: AWS::RDS::DBSubnetGroup
DependsOn:
- MyVPC
- MySubnet
- MySubnetA
- MySubnetB
Properties:
DBSubnetGroupDescription: Subnets to lauch the database
SubnetIds: 
-!Ref MySubnet
-!Ref MySubnetA  
-!Ref MySubnetB    

Answer 1

您应该在-和内在函数!Ref之间有一个空格，以便正确解析。遗憾的是，CloudFormation只有在创建堆栈时才会检测到这一点。

DBSubnetGroup:
Type: AWS::RDS::DBSubnetGroup
DependsOn:
- MyVPC
- MySubnet
- MySubnetA
- MySubnetB
Properties:
DBSubnetGroupDescription: Subnets to lauch the database
SubnetIds: 
- !Ref MySubnet
- !Ref MySubnetA  
- !Ref MySubnetB

Answer 2

Subnets:
Description: The array of Subnet IDs for the Subnet group
Type: List<AWS::EC2::Subnet::Id> 

如果您使用Subnetid作为EC2资源的引用，它将从您在参数中作为数组传递的列表中传递值。但是在subnetid中，它只允许字符串，因此你必须更改subnetid的数据类型。

Resources:
Ec2Resourse:
Type: AWS::EC2::Instance
Properties:
SubnetId: !Join [",", [!Select [0, !Ref Subnets]]]  

上面的代码将数组更改为字符串，并将部署我们从子网列表中选择的EC2。