Referencing the output of Parent stack in nested stack - Cloudformation - amazon-web-services

Question

I am trying to create the nested stack but having trouble as I am new to this and still in learning process. I have created the vpc with 2 private and 2 public subnets. Then attached the internet-facing elb to 2 public subnets. I think I am not referencing it right. Vpc is created but while creating elb there is an error Output 'VpcID' not found in stack I think there might be a problem in the syntax as I am changing my previous file to nested stack. I might not be referencing right in the Internet facing elb stack.
Root stack:
---
AWSTemplateFormatVersion: 2010-09-09
Parameters:
bucketname:
Type: String
Description: Path to the bucket
Default: wahaj-webserver
bucketpath:
Type: String
Description: Path to the bucket
Default: /nested-stack
Resources:
Vpcstack:
Type: AWS::CloudFormation::Stack
Properties:
TemplateURL: !Sub "https://${bucketname}.s3.us-east-2.amazonaws.com${bucketpath}/vpc1.yml"
elb:
DependsOn: Vpcstack
Type: AWS::CloudFormation::Stack
Properties:
TemplateURL: !Sub "https://${bucketname}.s3.us-east-2.amazonaws.com${bucketpath}/internetfacing-elb.yml"
Parameters:
SubnetA: !GetAtt Vpcstack.Outputs.SubnetA
SubnetB: !GetAtt Vpcstack.Outputs.SubnetB
VpcID: !GetAtt Vpcstack.Outputs.VpcID
Vpc stack:
---
AWSTemplateFormatVersion: 2010-09-09
Resources:
VPC:
Type: AWS::EC2::VPC
Properties:
CidrBlock: 11.0.0.0/16
EnableDnsSupport: true
EnableDnsHostnames: true
InstanceTenancy: default
InternetGateway:
Type: AWS::EC2::InternetGateway
VPCGatewayAttachment:
Type: AWS::EC2::VPCGatewayAttachment
Properties:
VpcId: !Ref VPC
InternetGatewayId: !Ref InternetGateway
SubnetA:
Type: AWS::EC2::Subnet
Properties:
AvailabilityZone: us-east-2a
VpcId: !Ref VPC
CidrBlock: 11.0.0.0/24
MapPublicIpOnLaunch: true
SubnetB:
Type: AWS::EC2::Subnet
Properties:
AvailabilityZone: us-east-2b
VpcId: !Ref VPC
CidrBlock: 11.0.1.0/24
MapPublicIpOnLaunch: true
SubnetC:
Type: AWS::EC2::Subnet
Properties:
AvailabilityZone: us-east-2a
VpcId: !Ref VPC
CidrBlock: 11.0.2.0/24
MapPublicIpOnLaunch: false
SubnetD:
Type: AWS::EC2::Subnet
Properties:
AvailabilityZone: us-east-2b
VpcId: !Ref VPC
CidrBlock: 11.0.3.0/24
MapPublicIpOnLaunch: false
RouteTable:
Type: AWS::EC2::RouteTable
Properties:
VpcId: !Ref VPC
RouteTable2:
Type: AWS::EC2::RouteTable
Properties:
VpcId: !Ref VPC
InternetRoute:
Type: AWS::EC2::Route
DependsOn: VPCGatewayAttachment
Properties:
DestinationCidrBlock: 0.0.0.0/0
GatewayId: !Ref InternetGateway
RouteTableId: !Ref RouteTable
SubnetARouteTableAssociation:
Type: AWS::EC2::SubnetRouteTableAssociation
Properties:
RouteTableId: !Ref RouteTable
SubnetId: !Ref SubnetA
SubnetBRouteTableAssociation:
Type: AWS::EC2::SubnetRouteTableAssociation
Properties:
RouteTableId: !Ref RouteTable
SubnetId: !Ref SubnetB
SubnetCRouteTableAssociation:
Type: AWS::EC2::SubnetRouteTableAssociation
Properties:
RouteTableId: !Ref RouteTable2
SubnetId: !Ref SubnetC
SubnetDRouteTableAssociation:
Type: AWS::EC2::SubnetRouteTableAssociation
Properties:
RouteTableId: !Ref RouteTable2
SubnetId: !Ref SubnetD
SecurityGroup:
Type: AWS::EC2::SecurityGroup
Properties:
GroupName: "Internet Group"
GroupDescription: "SSH traffic in, all traffic out."
VpcId: !Ref VPC
SecurityGroupIngress:
- IpProtocol: tcp
FromPort: "22"
ToPort: "22"
CidrIp: 0.0.0.0/0
SecurityGroupEgress:
- IpProtocol: -1
CidrIp: 0.0.0.0/0
NAT:
Type: AWS::EC2::NatGateway
Properties:
AllocationId:
Fn::GetAtt:
- EIP
- AllocationId
SubnetId:
Ref: SubnetA
Tags:
- Key: Name
Value: wahaj-nat
EIP:
DependsOn: VPCGatewayAttachment
Type: AWS::EC2::EIP
Properties:
Domain: VPC
Route:
Type: AWS::EC2::Route
Properties:
RouteTableId:
Ref: RouteTable2
DestinationCidrBlock: 0.0.0.0/0
NatGatewayId:
Ref: NAT
Outputs:
VpcID:
Description: VPC id
Value: !Ref VPC
Export:
Name: "VpcID"
SubnetA:
Description: public subnet
Value: !Ref SubnetA
Export:
Name: "SubnetA"
SubnetB:
Description: public subnet 2
Value: !Ref SubnetB
Export:
Name: "SubnetB"
SubnetC:
Description: priavte subnet
Value: !Ref SubnetC
Export:
Name: "SubnetC"
SubnetD:
Description: private subnet 2
Value: !Ref SubnetD
Export:
Name: "SubnetD"
Internet facing elb:
---
AWSTemplateFormatVersion: 2010-09-09
Resources:
wahajelb:
Type: AWS::EC2::SecurityGroup
Properties:
GroupName: wahaj-elb
VpcId:
Fn::ImportValue: "VpcID"
SecurityGroupIngress:
- IpProtocol: tcp
FromPort: 22
ToPort: 22
CidrIp: 0.0.0.0/0
Description: For traffic from Internet
- IpProtocol: tcp
FromPort: 80
ToPort: 80
CidrIp: 0.0.0.0/0
Description: For traffic from Internet
GroupDescription: Security Group for demo server
MyLoadBalancer:
Type: AWS::ElasticLoadBalancing::LoadBalancer
Properties:
Listeners:
- LoadBalancerPort: "80"
InstancePort: "80"
Protocol: HTTP
SecurityGroups:
- !Ref wahajelb
LoadBalancerName: wahajelb
Subnets:
- Fn::ImportValue: "SubnetA"
- Fn::ImportValue: "SubnetB"
HealthCheck:
Target: HTTP:80/SamplePage.php
HealthyThreshold: "3"
UnhealthyThreshold: "5"
Interval: "30"
Timeout: "5"
Outputs:
ec2:
Description: ec2
Value: !Ref MyLoadBalancer
Export:
Name: "MyLoadBalancer"
lgsg:
Description: lg-sg
Value: !GetAtt wahajelb.GroupId
Export:
Name: "lgsg"

Answer 1

Your Vpc stack has an out out of vpcID not VpcID.
This must be an exact string match for it to be successfully referenced in your Root stack
Update your Vpc stack to the below
---
AWSTemplateFormatVersion: 2010-09-09
Resources:
VPC:
Type: AWS::EC2::VPC
Properties:
CidrBlock: 11.0.0.0/16
EnableDnsSupport: true
EnableDnsHostnames: true
InstanceTenancy: default
InternetGateway:
Type: AWS::EC2::InternetGateway
VPCGatewayAttachment:
Type: AWS::EC2::VPCGatewayAttachment
Properties:
VpcId: !Ref VPC
InternetGatewayId: !Ref InternetGateway
SubnetA:
Type: AWS::EC2::Subnet
Properties:
AvailabilityZone: us-east-2a
VpcId: !Ref VPC
CidrBlock: 11.0.0.0/24
MapPublicIpOnLaunch: true
SubnetB:
Type: AWS::EC2::Subnet
Properties:
AvailabilityZone: us-east-2b
VpcId: !Ref VPC
CidrBlock: 11.0.1.0/24
MapPublicIpOnLaunch: true
SubnetC:
Type: AWS::EC2::Subnet
Properties:
AvailabilityZone: us-east-2a
VpcId: !Ref VPC
CidrBlock: 11.0.2.0/24
MapPublicIpOnLaunch: false
SubnetD:
Type: AWS::EC2::Subnet
Properties:
AvailabilityZone: us-east-2b
VpcId: !Ref VPC
CidrBlock: 11.0.3.0/24
MapPublicIpOnLaunch: false
RouteTable:
Type: AWS::EC2::RouteTable
Properties:
VpcId: !Ref VPC
RouteTable2:
Type: AWS::EC2::RouteTable
Properties:
VpcId: !Ref VPC
InternetRoute:
Type: AWS::EC2::Route
DependsOn: VPCGatewayAttachment
Properties:
DestinationCidrBlock: 0.0.0.0/0
GatewayId: !Ref InternetGateway
RouteTableId: !Ref RouteTable
SubnetARouteTableAssociation:
Type: AWS::EC2::SubnetRouteTableAssociation
Properties:
RouteTableId: !Ref RouteTable
SubnetId: !Ref SubnetA
SubnetBRouteTableAssociation:
Type: AWS::EC2::SubnetRouteTableAssociation
Properties:
RouteTableId: !Ref RouteTable
SubnetId: !Ref SubnetB
SubnetCRouteTableAssociation:
Type: AWS::EC2::SubnetRouteTableAssociation
Properties:
RouteTableId: !Ref RouteTable2
SubnetId: !Ref SubnetC
SubnetDRouteTableAssociation:
Type: AWS::EC2::SubnetRouteTableAssociation
Properties:
RouteTableId: !Ref RouteTable2
SubnetId: !Ref SubnetD
SecurityGroup:
Type: AWS::EC2::SecurityGroup
Properties:
GroupName: "Internet Group"
GroupDescription: "SSH traffic in, all traffic out."
VpcId: !Ref VPC
SecurityGroupIngress:
- IpProtocol: tcp
FromPort: "22"
ToPort: "22"
CidrIp: 0.0.0.0/0
SecurityGroupEgress:
- IpProtocol: -1
CidrIp: 0.0.0.0/0
NAT:
Type: AWS::EC2::NatGateway
Properties:
AllocationId:
Fn::GetAtt:
- EIP
- AllocationId
SubnetId:
Ref: SubnetA
Tags:
- Key: Name
Value: wahaj-nat
EIP:
DependsOn: VPCGatewayAttachment
Type: AWS::EC2::EIP
Properties:
Domain: VPC
Route:
Type: AWS::EC2::Route
Properties:
RouteTableId:
Ref: RouteTable2
DestinationCidrBlock: 0.0.0.0/0
NatGatewayId:
Ref: NAT
Outputs:
VpcID:
Description: VPC id
Value: !Ref VPC
Export:
Name:
Fn::Sub: "${AWS::StackName}-VpcID"
SubnetA:
Description: public subnet
Value: !Ref SubnetA
Export:
Name:
Fn::Sub: "${AWS::StackName}-SubnetA"
SubnetB:
Description: public subnet 2
Value: !Ref SubnetB
Export:
Name:
Fn::Sub: "${AWS::StackName}-SubnetB"
SubnetC:
Description: priavte subnet
Value: !Ref SubnetC
Export:
Name:
Fn::Sub: "${AWS::StackName}-SubnetC"
SubnetD:
Description: private subnet 2
Value: !Ref SubnetD
Export:
Name:
Fn::Sub: "${AWS::StackName}-SubnetD"