# CloudFormation template Rules syntax
The `Rules` section is an optional part of a CloudFormation template that enables custom validation logic. When included, this section contains rule functions that validate parameter values before CloudFormation creates or updates any resources.
Rules are useful when standard parameter constraints are insufficient. For example, when SSL is enabled, both a certificate and domain name must be provided. A rule can ensure that these dependencies are met.
## Syntax
The `Rules` section uses the following syntax:
### JSON
The `Rules` section of a template consists of the key name `Rules`, followed by a single colon. You must use braces to enclose all rule declarations. If you declare multiple rules, they're delimited by commas. For each rule, you declare a logical name in quotation marks followed by a colon and braces that enclose the rule condition and assertions.
```
{
"Rules": {
"LogicalRuleName1": {
"RuleCondition": {
"rule-specific intrinsic function": "Value"
},
"Assertions": [
{
"Assert": {
"rule-specific intrinsic function": "Value"
},
"AssertDescription": "Information about this assert"
},
{
"Assert": {
"rule-specific intrinsic function": "Value"
},
"AssertDescription": "Information about this assert"
}
]
},
"LogicalRuleName2": {
"Assertions": [
{
"Assert": {
"rule-specific intrinsic function": "Value"
},
"AssertDescription": "Information about this assert"
}
]
}
}
}
```
### YAML
```
Rules:
LogicalRuleName1:
RuleCondition:
rule-specific intrinsic function: Value
Assertions:
- Assert:
rule-specific intrinsic function: Value
AssertDescription: Information about this assert
- Assert:
rule-specific intrinsic function: Value
AssertDescription: Information about this assert
LogicalRuleName2:
Assertions:
- Assert:
rule-specific intrinsic function: Value
AssertDescription: Information about this assert
```
### Rules fields
The `Rules` section can include the following fields.
**Logical ID (also called *logical name*)**
A unique identifier for each rule.
**`RuleCondition` (optional)**
A property that determines when a rule takes effect. If you don't define a rule condition, the rule's assertions always take effect. For each rule, you can define only one rule condition.
**`Assertions` (required)**
One or more statements that specify the acceptable values for a particular parameter.
**`Assert`**
A condition that must evaluate to `true`.
**`AssertDescription`**
A message displayed when an assertion fails.
## Rule-specific intrinsic functions
To define your rules, you must use *rule-specific functions*, which are functions that can only be used in the `Rules` section of a template. While these functions can be nested, the final result of a rule condition or assertion must be either `true` or `false`.
The following rule functions are available:
+ [https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/intrinsic-function-reference-conditions.html#intrinsic-function-reference-conditions-and](https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/intrinsic-function-reference-conditions.html#intrinsic-function-reference-conditions-and)
+ [https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/intrinsic-function-reference-rules.html#fn-contains](https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/intrinsic-function-reference-rules.html#fn-contains)
+ [https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/intrinsic-function-reference-rules.html#fn-eachmemberequals](https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/intrinsic-function-reference-rules.html#fn-eachmemberequals)
+ [https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/intrinsic-function-reference-rules.html#fn-eachmemberin](https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/intrinsic-function-reference-rules.html#fn-eachmemberin)
+ [https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/intrinsic-function-reference-conditions.html#intrinsic-function-reference-conditions-equals](https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/intrinsic-function-reference-conditions.html#intrinsic-function-reference-conditions-equals)
+ [https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/intrinsic-function-reference-conditions.html#intrinsic-function-reference-conditions-if](https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/intrinsic-function-reference-conditions.html#intrinsic-function-reference-conditions-if)
+ [https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/intrinsic-function-reference-conditions.html#intrinsic-function-reference-conditions-not](https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/intrinsic-function-reference-conditions.html#intrinsic-function-reference-conditions-not)
+ [https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/intrinsic-function-reference-conditions.html#intrinsic-function-reference-conditions-or](https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/intrinsic-function-reference-conditions.html#intrinsic-function-reference-conditions-or)
+ [https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/intrinsic-function-reference-rules.html#fn-refall](https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/intrinsic-function-reference-rules.html#fn-refall)
+ [https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/intrinsic-function-reference-rules.html#fn-valueof](https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/intrinsic-function-reference-rules.html#fn-valueof)
+ [https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/intrinsic-function-reference-rules.html#fn-valueofall](https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/intrinsic-function-reference-rules.html#fn-valueofall)
These functions are used in the condition or assertions of a rule. The condition property determines if CloudFormation applies the assertions. If the condition evaluates to `true`, CloudFormation evaluates the assertions to verify whether a parameter value is valid when a provisioned product is created or updated. If a parameter value is invalid, CloudFormation does not create or update the stack. If the condition evaluates to `false`, CloudFormation doesn't check the parameter value and proceeds with the stack operation.
## Examples
**Topics**
+ [Conditionally verify a parameter value](#template-constraint-rules-example-verify)
+ [Cross-parameter validation](#template-cross-parameter-rules-example)
### Conditionally verify a parameter value
In the following example, the two rules check the value of the `InstanceType` parameter. Depending on the value of the environment parameter (`test` or `prod`), the user must specify `t3.medium` or `t3.large` for the `InstanceType` parameter. The `InstanceType` and `Environment` parameters must be declared in the `Parameters` section of the same template.
#### JSON
```
{
"Rules": {
"testInstanceType": {
"RuleCondition": {
"Fn::Equals": [
{"Ref": "Environment"},
"test"
]
},
"Assertions": [
{
"Assert": {
"Fn::Contains": [
["t3.medium"],
{"Ref": "InstanceType"}
]
},
"AssertDescription": "For a test environment, the instance type must be t3.medium"
}
]
},
"prodInstanceType": {
"RuleCondition": {
"Fn::Equals": [
{"Ref": "Environment"},
"prod"
]
},
"Assertions": [
{
"Assert": {
"Fn::Contains": [
["t3.large"],
{"Ref": "InstanceType"}
]
},
"AssertDescription": "For a production environment, the instance type must be t3.large"
}
]
}
}
}
```
#### YAML
```
Rules:
testInstanceType:
RuleCondition: !Equals
- !Ref Environment
- test
Assertions:
- Assert:
'Fn::Contains':
- - t3.medium
- !Ref InstanceType
AssertDescription: 'For a test environment, the instance type must be t3.medium'
prodInstanceType:
RuleCondition: !Equals
- !Ref Environment
- prod
Assertions:
- Assert:
'Fn::Contains':
- - t3.large
- !Ref InstanceType
AssertDescription: 'For a production environment, the instance type must be t3.large'
```
### Cross-parameter validation
The following sample templates demonstrate the use of rules for cross-parameter validations. They create a sample website running on an Auto Scaling group behind a load balancer. The website is available on port 80 or 443 depending on input parameters. The instances in the Auto Scaling group can be configured to listen on any port (with 8888 as the default).
The rules in this template validate input parameters before stack creation. They verify that all subnets belong to the specified VPC and ensure that when the `UseSSL` parameter is set to `Yes`, both an SSL certificate ARN and hosted zone name are provided.
**Note**
You will be billed for the AWS resources used if you create a stack from this template.
#### JSON
```
{
"AWSTemplateFormatVersion": "2010-09-09",
"Parameters": {
"VpcId": {
"Type": "AWS::EC2::VPC::Id",
"Description": "VpcId of your existing Virtual Private Cloud (VPC)",
"ConstraintDescription": "must be the VPC Id of an existing Virtual Private Cloud."
},
"Subnets": {
"Type": "List",
"Description": "The list of SubnetIds in your Virtual Private Cloud (VPC)",
"ConstraintDescription": "must be a list of at least two existing subnets associated with at least two different availability zones."
},
"InstanceType": {
"Description": "WebServer EC2 instance type",
"Type": "String",
"Default": "t2.micro",
"AllowedValues": ["t2.micro", "t3.micro"],
"ConstraintDescription": "must be a valid EC2 instance type."
},
"KeyName": {
"Description": "Name of an existing EC2 KeyPair to enable SSH access to the instances",
"Type": "AWS::EC2::KeyPair::KeyName",
"ConstraintDescription": "must be the name of an existing EC2 KeyPair."
},
"SSHLocation": {
"Description": "The IP address range that can be used to SSH to the EC2 instances",
"Type": "String",
"MinLength": "9",
"MaxLength": "18",
"Default": "0.0.0.0/0",
"AllowedPattern": "(\\d{1,3})\\.(\\d{1,3})\\.(\\d{1,3})\\.(\\d{1,3})/(\\d{1,2})",
"ConstraintDescription": "must be a valid IP CIDR range of the form x.x.x.x/x."
},
"UseSSL": {
"AllowedValues": ["Yes", "No"],
"Default": "No",
"Description": "Select \"Yes\" to implement SSL, \"No\" to skip (default).",
"Type": "String"
},
"ALBSSLCertificateARN": {
"Default": "",
"Description": "[Optional] The ARN of the SSL certificate to be used for the Application Load Balancer",
"Type": "String"
},
"HostedZoneName": {
"AllowedPattern": "^$|(([a-zA-Z0-9]|[a-zA-Z0-9][a-zA-Z0-9\\-]*[a-zA-Z0-9])\\.)*([A-Za-z0-9]|[A-Za-z0-9][A-Za-z0-9\\-]*[A-Za-z0-9])$",
"Default": "",
"Description": "[Optional] The domain name of a valid Hosted Zone on AWS.",
"Type": "String"
}
},
"Conditions": {
"UseALBSSL": {"Fn::Equals": [{"Ref": "UseSSL"}, "Yes"]}
},
"Rules": {
"SubnetsInVPC": {
"Assertions": [
{
"Assert": {"Fn::EachMemberEquals": [{"Fn::ValueOf": ["Subnets", "VpcId"]}, {"Ref": "VpcId"}]},
"AssertDescription": "All subnets must be in the VPC"
}
]
},
"ValidateHostedZone": {
"RuleCondition": {"Fn::Equals": [{"Ref": "UseSSL"}, "Yes"]},
"Assertions": [
{
"Assert": {"Fn::Not": [{"Fn::Equals": [{"Ref": "ALBSSLCertificateARN"}, ""]}]},
"AssertDescription": "ACM Certificate value cannot be empty if SSL is required"
},
{
"Assert": {"Fn::Not": [{"Fn::Equals": [{"Ref": "HostedZoneName"}, ""]}]},
"AssertDescription": "Route53 Hosted Zone Name is mandatory when SSL is required"
}
]
}
},
"Resources": {
"WebServerGroup": {
"Type": "AWS::AutoScaling::AutoScalingGroup",
"Properties": {
"VPCZoneIdentifier": {"Ref": "Subnets"},
"LaunchTemplate": {
"LaunchTemplateId": {"Ref": "LaunchTemplate"},
"Version": {"Fn::GetAtt": ["LaunchTemplate","LatestVersionNumber"]}
},
"MinSize": "2",
"MaxSize": "2",
"TargetGroupARNs": [{"Ref": "ALBTargetGroup"}]
},
"CreationPolicy": {
"ResourceSignal": {"Timeout": "PT15M"}
},
"UpdatePolicy": {
"AutoScalingRollingUpdate": {
"MinInstancesInService": "1",
"MaxBatchSize": "1",
"PauseTime": "PT15M",
"WaitOnResourceSignals": true
}
}
},
"LaunchTemplate": {
"Type": "AWS::EC2::LaunchTemplate",
"Metadata": {
"Comment": "Install a simple application",
"AWS::CloudFormation::Init": {
"config": {
"packages": {"yum": {"httpd": []}},
"files": {
"/var/www/html/index.html": {
"content": {"Fn::Join": ["\n", ["Congratulations, you have successfully launched the AWS CloudFormation sample.
"]]},
"mode": "000644",
"owner": "root",
"group": "root"
},
"/etc/cfn/cfn-hup.conf": {
"content": {"Fn::Join": ["", [
"[main]\n",
"stack=", {"Ref": "AWS::StackId"}, "\n",
"region=", {"Ref": "AWS::Region"}, "\n"
]]},
"mode": "000400",
"owner": "root",
"group": "root"
},
"/etc/cfn/hooks.d/cfn-auto-reloader.conf": {
"content": {"Fn::Join": ["", [
"[cfn-auto-reloader-hook]\n",
"triggers=post.update\n",
"path=Resources.LaunchTemplate.Metadata.AWS::CloudFormation::Init\n",
"action=/opt/aws/bin/cfn-init -v ",
" --stack ", {"Ref": "AWS::StackName"},
" --resource LaunchTemplate ",
" --region ", {"Ref": "AWS::Region"}, "\n",
"runas=root\n"
]]},
"mode": "000400",
"owner": "root",
"group": "root"
}
},
"services": {
"sysvinit": {
"httpd": {
"enabled": "true",
"ensureRunning": "true"
},
"cfn-hup": {
"enabled": "true",
"ensureRunning": "true",
"files": [
"/etc/cfn/cfn-hup.conf",
"/etc/cfn/hooks.d/cfn-auto-reloader.conf"
]
}
}
}
}
}
},
"Properties": {
"LaunchTemplateName": {"Fn::Sub": "${AWS::StackName}-launch-template"},
"LaunchTemplateData": {
"ImageId": "{{resolve:ssm:/aws/service/ami-amazon-linux-latest/amzn2-ami-hvm-x86_64-gp2}}",
"SecurityGroupIds": [{"Ref": "InstanceSecurityGroup"}],
"InstanceType": {"Ref": "InstanceType"},
"KeyName": {"Ref": "KeyName"},
"UserData": {
"Fn::Base64": {"Fn::Join": ["", [
"#!/bin/bash\n",
"yum install -y aws-cfn-bootstrap\n",
"/opt/aws/bin/cfn-init -v ",
" --stack ", {"Ref": "AWS::StackName"},
" --resource LaunchTemplate ",
" --region ", {"Ref": "AWS::Region"}, "\n",
"/opt/aws/bin/cfn-signal -e $? ",
" --stack ", {"Ref": "AWS::StackName"},
" --resource WebServerGroup ",
" --region ", {"Ref": "AWS::Region"}, "\n"
]]}
}
}
}
},
"ELBSecurityGroup": {
"Type": "AWS::EC2::SecurityGroup",
"Properties": {
"GroupDescription": "Allow access to the ELB",
"VpcId": {"Ref": "VpcId"},
"SecurityGroupIngress": [{
"Fn::If": [
"UseALBSSL",
{
"IpProtocol": "tcp",
"FromPort": 443,
"ToPort": 443,
"CidrIp": "0.0.0.0/0"
},
{
"IpProtocol": "tcp",
"FromPort": 80,
"ToPort": 80,
"CidrIp": "0.0.0.0/0"
}
]
}]
}
},
"ApplicationLoadBalancer": {
"Type": "AWS::ElasticLoadBalancingV2::LoadBalancer",
"Properties": {
"Subnets": {"Ref": "Subnets"},
"SecurityGroups": [{"Ref": "ELBSecurityGroup"}]
}
},
"ALBListener": {
"Type": "AWS::ElasticLoadBalancingV2::Listener",
"Properties": {
"DefaultActions": [{
"Type": "forward",
"TargetGroupArn": {"Ref": "ALBTargetGroup"}
}],
"LoadBalancerArn": {"Ref": "ApplicationLoadBalancer"},
"Port": {"Fn::If": ["UseALBSSL", 443, 80]},
"Protocol": {"Fn::If": ["UseALBSSL", "HTTPS", "HTTP"]},
"Certificates": [{
"Fn::If": [
"UseALBSSL",
{"CertificateArn": {"Ref": "ALBSSLCertificateARN"}},
{"Ref": "AWS::NoValue"}
]
}]
}
},
"ALBTargetGroup": {
"Type": "AWS::ElasticLoadBalancingV2::TargetGroup",
"Properties": {
"HealthCheckIntervalSeconds": 30,
"HealthCheckTimeoutSeconds": 5,
"HealthyThresholdCount": 3,
"Port": 80,
"Protocol": "HTTP",
"UnhealthyThresholdCount": 5,
"VpcId": {"Ref": "VpcId"}
}
},
"InstanceSecurityGroup": {
"Type": "AWS::EC2::SecurityGroup",
"Properties": {
"GroupDescription": "Enable SSH access and HTTP access on the inbound port",
"SecurityGroupIngress": [
{
"IpProtocol": "tcp",
"FromPort": 80,
"ToPort": 80,
"SourceSecurityGroupId": {"Fn::Select": [0, {"Fn::GetAtt": ["ApplicationLoadBalancer", "SecurityGroups"]}]}
},
{
"IpProtocol": "tcp",
"FromPort": 22,
"ToPort": 22,
"CidrIp": {"Ref": "SSHLocation"}
}
],
"VpcId": {"Ref": "VpcId"}
}
},
"RecordSet": {
"Type": "AWS::Route53::RecordSetGroup",
"Condition": "UseALBSSL",
"Properties": {
"HostedZoneName": {"Fn::Join": ["", [{"Ref": "HostedZoneName"}, "."]]},
"RecordSets": [{
"Name": {"Fn::Join": ["", [
{"Fn::Select": ["0", {"Fn::Split": [".", {"Fn::GetAtt": ["ApplicationLoadBalancer", "DNSName"]}]}]},
".",
{"Ref": "HostedZoneName"},
"."
]]},
"Type": "A",
"AliasTarget": {
"DNSName": {"Fn::GetAtt": ["ApplicationLoadBalancer", "DNSName"]},
"EvaluateTargetHealth": true,
"HostedZoneId": {"Fn::GetAtt": ["ApplicationLoadBalancer", "CanonicalHostedZoneID"]}
}
}]
}
}
},
"Outputs": {
"URL": {
"Description": "URL of the website",
"Value": {"Fn::Join": ["", [
{"Fn::If": [
"UseALBSSL",
{"Fn::Join": ["", [
"https://",
{"Fn::Join": ["", [
{"Fn::Select": ["0", {"Fn::Split": [".", {"Fn::GetAtt": ["ApplicationLoadBalancer", "DNSName"]}]}]},
".",
{"Ref": "HostedZoneName"},
"."
]]}
]]},
{"Fn::Join": ["", [
"http://",
{"Fn::GetAtt": ["ApplicationLoadBalancer", "DNSName"]}
]]}
]}
]]}
}
}
}
```
#### YAML
```
AWSTemplateFormatVersion: 2010-09-09
Parameters:
VpcId:
Type: AWS::EC2::VPC::Id
Description: VpcId of your existing Virtual Private Cloud (VPC)
ConstraintDescription: must be the VPC Id of an existing Virtual Private Cloud.
Subnets:
Type: List
Description: The list of SubnetIds in your Virtual Private Cloud (VPC)
ConstraintDescription: >-
must be a list of at least two existing subnets associated with at least
two different availability zones. They should be residing in the selected
Virtual Private Cloud.
InstanceType:
Description: WebServer EC2 instance type
Type: String
Default: t2.micro
AllowedValues:
- t2.micro
- t3.micro
ConstraintDescription: must be a valid EC2 instance type.
KeyName:
Description: Name of an existing EC2 KeyPair to enable SSH access to the instances
Type: AWS::EC2::KeyPair::KeyName
ConstraintDescription: must be the name of an existing EC2 KeyPair.
SSHLocation:
Description: The IP address range that can be used to SSH to the EC2 instances
Type: String
MinLength: '9'
MaxLength: '18'
Default: 0.0.0.0/0
AllowedPattern: '(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})/(\d{1,2})'
ConstraintDescription: must be a valid IP CIDR range of the form x.x.x.x/x.
UseSSL:
AllowedValues:
- 'Yes'
- 'No'
ConstraintDescription: Select Yes to create a HTTPS Listener
Default: 'No'
Description: 'Select "Yes" to implement SSL, "No" to skip (default).'
Type: String
ALBSSLCertificateARN:
Default: ''
Description: >-
[Optional] The ARN of the SSL certificate to be used for the Application
Load Balancer
Type: String
HostedZoneName:
AllowedPattern: >-
^$|(([a-zA-Z0-9]|[a-zA-Z0-9][a-zA-Z0-9\-]*[a-zA-Z0-9])\.)*([A-Za-z0-9]|[A-Za-z0-9][A-Za-z0-9\-]*[A-Za-z0-9])$
Default: ''
Description: '[Optional] The domain name of a valid Hosted Zone on AWS.'
Type: String
Conditions:
UseALBSSL: !Equals
- !Ref UseSSL
- 'Yes'
Rules:
SubnetsInVPC:
Assertions:
- Assert:
'Fn::EachMemberEquals':
- 'Fn::ValueOf':
- Subnets
- VpcId
- Ref: VpcId
AssertDescription: All subnets must be in the VPC
ValidateHostedZone:
RuleCondition: !Equals
- !Ref UseSSL
- 'Yes'
Assertions:
- Assert: !Not
- !Equals
- !Ref ALBSSLCertificateARN
- ''
AssertDescription: ACM Certificate value cannot be empty if SSL is required
- Assert: !Not
- !Equals
- !Ref HostedZoneName
- ''
AssertDescription: Route53 Hosted Zone Name is mandatory when SSL is required
Resources:
WebServerGroup:
Type: AWS::AutoScaling::AutoScalingGroup
Properties:
VPCZoneIdentifier: !Ref Subnets
LaunchTemplate:
LaunchTemplateId: !Ref LaunchTemplate
Version: !GetAtt LaunchTemplate.LatestVersionNumber
MinSize: '2'
MaxSize: '2'
TargetGroupARNs:
- !Ref ALBTargetGroup
CreationPolicy:
ResourceSignal:
Timeout: PT15M
UpdatePolicy:
AutoScalingRollingUpdate:
MinInstancesInService: '1'
MaxBatchSize: '1'
PauseTime: PT15M
WaitOnResourceSignals: 'true'
LaunchTemplate:
Type: AWS::EC2::LaunchTemplate
Metadata:
Comment: Install a simple application
AWS::CloudFormation::Init:
config:
packages:
yum:
httpd: []
files:
/var/www/html/index.html:
content: !Join
- |+
- - >-
Congratulations, you have successfully launched the AWS
CloudFormation sample.
mode: '000644'
owner: root
group: root
/etc/cfn/cfn-hup.conf:
content: !Sub |
[main]
stack=${AWS::StackId}
region=${AWS::Region}
mode: '000400'
owner: root
group: root
/etc/cfn/hooks.d/cfn-auto-reloader.conf:
content: !Sub |-
[cfn-auto-reloader-hook]
triggers=post.update
path=Resources.LaunchTemplate.Metadata.AWS::CloudFormation::Init
action=/opt/aws/bin/cfn-init -v --stack ${AWS::StackName} --resource LaunchTemplate --region ${AWS::Region}
runas=root
mode: '000400'
owner: root
group: root
services:
sysvinit:
httpd:
enabled: 'true'
ensureRunning: 'true'
cfn-hup:
enabled: 'true'
ensureRunning: 'true'
files:
- /etc/cfn/cfn-hup.conf
- /etc/cfn/hooks.d/cfn-auto-reloader.conf
Properties:
LaunchTemplateName: !Sub ${AWS::StackName}-launch-template
LaunchTemplateData:
ImageId: '{{resolve:ssm:/aws/service/ami-amazon-linux-latest/amzn2-ami-hvm-x86_64-gp2}}'
SecurityGroupIds:
- !Ref InstanceSecurityGroup
InstanceType: !Ref InstanceType
KeyName: !Ref KeyName
UserData: !Base64
Fn::Sub: |
#!/bin/bash
yum install -y aws-cfn-bootstrap
/opt/aws/bin/cfn-init -v --stack ${AWS::StackName} --resource LaunchTemplate --region ${AWS::Region}
/opt/aws/bin/cfn-signal -e $? --stack ${AWS::StackName} --resource WebServerGroup --region ${AWS::Region}
ELBSecurityGroup:
Type: AWS::EC2::SecurityGroup
Properties:
GroupDescription: Allow access to the ELB
VpcId: !Ref VpcId
SecurityGroupIngress:
- !If
- UseALBSSL
- IpProtocol: tcp
FromPort: 443
ToPort: 443
CidrIp: 0.0.0.0/0
- IpProtocol: tcp
FromPort: 80
ToPort: 80
CidrIp: 0.0.0.0/0
ApplicationLoadBalancer:
Type: AWS::ElasticLoadBalancingV2::LoadBalancer
Properties:
Subnets: !Ref Subnets
SecurityGroups:
- !Ref ELBSecurityGroup
ALBListener:
Type: AWS::ElasticLoadBalancingV2::Listener
Properties:
DefaultActions:
- Type: forward
TargetGroupArn: !Ref ALBTargetGroup
LoadBalancerArn: !Ref ApplicationLoadBalancer
Port: !If
- UseALBSSL
- 443
- 80
Protocol: !If
- UseALBSSL
- HTTPS
- HTTP
Certificates:
- !If
- UseALBSSL
- CertificateArn: !Ref ALBSSLCertificateARN
- !Ref 'AWS::NoValue'
ALBTargetGroup:
Type: AWS::ElasticLoadBalancingV2::TargetGroup
Properties:
HealthCheckIntervalSeconds: 30
HealthCheckTimeoutSeconds: 5
HealthyThresholdCount: 3
Port: 80
Protocol: HTTP
UnhealthyThresholdCount: 5
VpcId: !Ref VpcId
InstanceSecurityGroup:
Type: AWS::EC2::SecurityGroup
Properties:
GroupDescription: Enable SSH access and HTTP access on the inbound port
SecurityGroupIngress:
- IpProtocol: tcp
FromPort: 80
ToPort: 80
SourceSecurityGroupId: !Select
- 0
- !GetAtt
- ApplicationLoadBalancer
- SecurityGroups
- IpProtocol: tcp
FromPort: 22
ToPort: 22
CidrIp: !Ref SSHLocation
VpcId: !Ref VpcId
RecordSet:
Type: AWS::Route53::RecordSetGroup
Condition: UseALBSSL
Properties:
HostedZoneName: !Join
- ''
- - !Ref HostedZoneName
- .
RecordSets:
- Name: !Join
- ''
- - !Select
- '0'
- !Split
- .
- !GetAtt
- ApplicationLoadBalancer
- DNSName
- .
- !Ref HostedZoneName
- .
Type: A
AliasTarget:
DNSName: !GetAtt
- ApplicationLoadBalancer
- DNSName
EvaluateTargetHealth: true
HostedZoneId: !GetAtt
- ApplicationLoadBalancer
- CanonicalHostedZoneID
Outputs:
URL:
Description: URL of the website
Value: !Join
- ''
- - !If
- UseALBSSL
- !Join
- ''
- - 'https://'
- !Join
- ''
- - !Select
- '0'
- !Split
- .
- !GetAtt
- ApplicationLoadBalancer
- DNSName
- .
- !Ref HostedZoneName
- .
- !Join
- ''
- - 'http://'
- !GetAtt
- ApplicationLoadBalancer
- DNSName
```