This is the new *CloudFormation Template Reference Guide*. Please update your bookmarks and links. For help getting started with CloudFormation, see the [AWS CloudFormation User Guide](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/Welcome.html).
# `Fn::ForEach`
The `Fn::ForEach` intrinsic function takes a collection and a fragment, and applies the items in the collection to the identifier in the provided fragment. `Fn::ForEach` can contain other intrinsic functions, including `Fn::ForEach` itself, and be used within the `Conditions`, `Outputs`, and `Resources` (including the resource properties) sections. It can't be used in any of the following sections, `AWSTemplateFormatVersion`, `Description`, `Metadata`, `Transform`, `Parameters`, `Mappings`, `Rules`, or `Hooks` sections.
If you use the `Fn::ForEach` intrinsic function in your template, you must also use the [`AWS::LanguageExtensions` transform](transform-aws-languageextensions.md) .
Using the `Fn::ForEach` intrinsic function does not change the quotas, which apply to the resultant template. Quotas include the maximum size of a template and the maximum number of resources in a template. For more information, see [Understand CloudFormation quotas](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/cloudformation-limits.html) in the *AWS CloudFormation User Guide*.
## Declaration
### JSON
```
"Fn::ForEach::LoopLogicalName": [
"Identifier",
["Value1","Value2"], // Collection
{"OutputKey": {OutputValue}}
]
```
### YAML
```
'Fn::ForEach::LoopLogicalName':
- Identifier
- - Value1 # Collection
- Value2
- 'OutputKey':
OutputValue
```
## Parameters
*Loop logical name*
A logical ID for the loop. The name must be unique within the template and can't conflict with any logical ID values in the `Resources` section of the template. This name isn't in the transformed output. It’s used for internal reference within the CloudFormation template itself.
*Identifier*
An identifier for the placeholder that gets replaced in the `OutputKey` and `OutputValue` parameters. All instances of `${Identifier}` or `&{Identifier}` in the `OutputKey` and `OutputValue` parameters will be replaced with the values from the `Collection` parameter.
*Collection*
The collection of values to iterate over. This can be an array in this parameter, or it can be a [`Ref`](intrinsic-function-reference-ref.md) to a `CommaDelimitedList`. When using `&{Identifier}`, non-alphanumeric characters can be passed in the `Collection`.
*Output key*
The key in the transformed template. `${Identifier}` or `&{Identifier}` must be included within the `OutputKey` parameter. For example, if `Fn::ForEach` is used in the `Resources` section of the template, this is the logical ID of each resource.
The `&{}` syntax allows non-alphanumeric characters in the `Collection` to be used in `OutputKey` parameter. For an example of this, see [Passing non-alphanumeric characters within the `Collection` for `Fn::ForEach`](intrinsic-function-reference-foreach-example-resource.md#intrinsic-function-reference-foreach-example-non-alphanumeric).
*Output value*
The value that's replicated in the transformed template for each item in the `Collection` parameter. For example, if `Fn::ForEach` is used in the `Resources` section of the template, this is the template fragment that's repeated to configure each resource.
## Return value
An expanded object that contains the object fragment repeated once for each item in the collection, where the identifier in the fragment is replaced with the item from the collection.
## Supported functions
You can use the following functions within `Fn::ForEach`.
+ Condition functions:
+ [`Fn::And`](intrinsic-function-reference-conditions.md#intrinsic-function-reference-conditions-and)
+ [`Fn::Equals`](intrinsic-function-reference-conditions.md#intrinsic-function-reference-conditions-equals)
+ [`Fn::If`](intrinsic-function-reference-conditions.md#intrinsic-function-reference-conditions-if)
+ [`Fn::Not`](intrinsic-function-reference-conditions.md#intrinsic-function-reference-conditions-not)
+ [`Fn::Or`](intrinsic-function-reference-conditions.md#intrinsic-function-reference-conditions-or)
+ [`Fn::Base64`](intrinsic-function-reference-base64.md)
+ [`Fn::FindInMap`](intrinsic-function-reference-findinmap.md)
+ [`Fn::GetAtt`](intrinsic-function-reference-getatt.md)
+ [`Fn::GetAZs`](intrinsic-function-reference-getavailabilityzones.md)
+ [`Fn::ImportValue`](intrinsic-function-reference-importvalue.md)
+ [`Fn::Join`](intrinsic-function-reference-join.md)
+ [`Fn::Length`](intrinsic-function-reference-length.md)
+ [`Fn::Transform`](intrinsic-function-reference-transform.md)
+ [`Fn::Select`](intrinsic-function-reference-select.md)
+ [`Fn::Sub`](intrinsic-function-reference-sub.md)
+ [`Fn::ToJsonString`](intrinsic-function-reference-ToJsonString.md)
+ [`Ref`](intrinsic-function-reference-ref.md)
## Examples
You can find examples for the `Conditions`, `Outputs`, and `Resources` sections in [Examples](intrinsic-function-reference-foreach-examples.md).
# Examples
**Topics**
+ [Examples of `Fn::ForEach` in the `Resources` section](intrinsic-function-reference-foreach-example-resource.md)
+ [Examples of `Fn::ForEach` in the `Outputs` section](intrinsic-function-reference-foreach-example-outputs.md)
+ [Examples of `Fn::ForEach` in the `Conditions` section](intrinsic-function-reference-foreach-example-conditions.md)
# Examples of `Fn::ForEach` in the `Resources` section
These examples demonstrate using the `Fn::ForEach` intrinsic function in the `Resources` section. For more information about this section, see [Resources](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/resources-section-structure.html) in the *AWS CloudFormation User Guide*.
**Topics**
+ [Replicate an Amazon SNS resource](#intrinsic-function-reference-foreach-example-replicate-resource)
+ [Replicate an Amazon DynamoDB resource](#intrinsic-function-reference-foreach-example-replicate-ddb-resource)
+ [Replicate multiple resources](#intrinsic-function-reference-foreach-example-replicate-multiple-resources)
+ [Replicate multiple resources using a nested `Fn::ForEach` loops](#intrinsic-function-reference-foreach-example-nested-loop-resources)
+ [Reference replicated properties for an Amazon EC2 resource](#intrinsic-function-reference-foreach-example-reference-replicated-resource)
+ [Replicate properties for an Amazon EC2 resource](#intrinsic-function-reference-foreach-example-replicate-resource-properties)
+ [Passing non-alphanumeric characters within the `Collection` for `Fn::ForEach`](#intrinsic-function-reference-foreach-example-non-alphanumeric)
## Replicate an Amazon SNS resource
This example snippet returns a list of four Amazon SNS topics, with the logical ID corresponding to the items in the collection (`Success`, `Failure`, `Timeout`, `Unknown`), with a matching `TopicName` and `FifoTopic` set to `true`.
**Note**
For templates that need to work with both FIFO and standard topics, you can use the `DisplayName` property instead of `TopicName`. This allows CloudFormation to automatically generate topic names with the appropriate `.fifo` suffix when `FifoTopic` is `true`. Simply replace `TopicName` with `DisplayName: !Ref TopicName` in the `Properties` section.
### JSON
```
{
"AWSTemplateFormatVersion": "2010-09-09",
"Transform": "AWS::LanguageExtensions",
"Resources": {
"Fn::ForEach::Topics": [
"TopicName",
["Success", "Failure", "Timeout", "Unknown"],
{
"SnsTopic${TopicName}": {
"Type": "AWS::SNS::Topic",
"Properties": {
"TopicName": {"Fn::Sub": "${TopicName}.fifo"},
"FifoTopic": true
}
}
}
]
}
}
```
### YAML
```
AWSTemplateFormatVersion: 2010-09-09
Transform: AWS::LanguageExtensions
Resources:
'Fn::ForEach::Topics':
- TopicName
- [Success, Failure, Timeout, Unknown]
- 'SnsTopic${TopicName}':
Type: AWS::SNS::Topic
Properties:
TopicName: !Sub '${TopicName}.fifo'
FifoTopic: true
```
The transformed template will be equivalent to the following template:
```
AWSTemplateFormatVersion: 2010-09-09
Resources:
SnsTopicSuccess:
Type: AWS::SNS::Topic
Properties:
TopicName: Success.fifo
FifoTopic: true
SnsTopicFailure:
Type: AWS::SNS::Topic
Properties:
TopicName: Failure.fifo
FifoTopic: true
SnsTopicTimeout:
Type: AWS::SNS::Topic
Properties:
TopicName: Timeout.fifo
FifoTopic: true
SnsTopicUnknown:
Type: AWS::SNS::Topic
Properties:
TopicName: Unknown.fifo
FifoTopic: true
```
## Replicate an Amazon DynamoDB resource
This example snippet creates four [AWS::DynamoDB::Table](https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/aws-resource-dynamodb-table.html) resources with names such as `Points`, `Score`, etc.
### JSON
```
{
"AWSTemplateFormatVersion": "2010-09-09",
"Transform": "AWS::LanguageExtensions",
"Resources": {
"Fn::ForEach::Tables": [
"TableName",
["Points", "Score", "Name", "Leaderboard"],
{
"DynamoDB${TableName}": {
"Type": "AWS::DynamoDB::Table",
"Properties": {
"TableName": {
"Ref": "TableName"
},
"AttributeDefinitions": [
{
"AttributeName": "id",
"AttributeType": "S"
}
],
"KeySchema": [
{
"AttributeName": "id",
"KeyType": "HASH"
}
],
"ProvisionedThroughput": {
"ReadCapacityUnits": "5",
"WriteCapacityUnits": "5"
}
}
}
}
]
}
}
```
### YAML
```
AWSTemplateFormatVersion: 2010-09-09
Transform: AWS::LanguageExtensions
Resources:
'Fn::ForEach::Tables':
- TableName
- [Points, Score, Name, Leaderboard]
- 'DynamoDB${TableName}':
Type: AWS::DynamoDB::Table
Properties:
TableName: !Ref TableName
AttributeDefinitions:
- AttributeName: id
AttributeType: S
KeySchema:
- AttributeName: id
KeyType: HASH
ProvisionedThroughput:
ReadCapacityUnits: '5'
WriteCapacityUnits: '5'
```
The transformed template will be equivalent to the following template:
```
AWSTemplateFormatVersion: 2010-09-09
Transform: AWS::LanguageExtensions
Resources:
DynamoDBPoints:
Type: AWS::DynamoDB::Table
Properties:
TableName: Points
AttributeDefinitions:
- AttributeName: id
AttributeType: S
KeySchema:
- AttributeName: id
KeyType: HASH
ProvisionedThroughput:
ReadCapacityUnits: '5'
WriteCapacityUnits: '5'
DynamoDBScore:
Type: AWS::DynamoDB::Table
Properties:
TableName: Score
AttributeDefinitions:
- AttributeName: id
AttributeType: S
KeySchema:
- AttributeName: id
KeyType: HASH
ProvisionedThroughput:
ReadCapacityUnits: '5'
WriteCapacityUnits: '5'
DynamoDBName:
Type: AWS::DynamoDB::Table
Properties:
TableName: Name
AttributeDefinitions:
- AttributeName: id
AttributeType: S
KeySchema:
- AttributeName: id
KeyType: HASH
ProvisionedThroughput:
ReadCapacityUnits: '5'
WriteCapacityUnits: '5'
DynamoDBLeaderboard:
Type: AWS::DynamoDB::Table
Properties:
TableName: Leaderboard
AttributeDefinitions:
- AttributeName: id
AttributeType: S
KeySchema:
- AttributeName: id
KeyType: HASH
ProvisionedThroughput:
ReadCapacityUnits: '5'
WriteCapacityUnits: '5'
```
## Replicate multiple resources
This example creates multiple instances of [AWS::EC2::NatGateway](https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/aws-resource-ec2-natgateway.html) and [AWS::EC2::EIP](https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/aws-resource-ec2-eip.html) using a naming convention of `"{ResourceType}${Identifier}"`. You can declare multiple resource types under one `Fn::ForEach` loop to take advantage of a single identifier.
Unique values for each element in the collection are defined within the `Mappings` section, where the [`Fn::FindInMap`](intrinsic-function-reference-findinmap.md) intrinsic function is used to reference the corresponding value. If `Fn::FindInMap` is unable to find the corresponding identifier, the `Condition` property will not be set resolving to `!Ref AWS:::NoValue`.
### JSON
```
{
"AWSTemplateFormatVersion": "2010-09-09",
"Transform": "AWS::LanguageExtensions",
"Conditions": {
"TwoNatGateways": {"Fn::Equals": [{"Ref": "AWS::Region"}, "us-east-1"]},
"ThreeNatGateways": {"Fn::Equals": [{"Ref": "AWS::Region"}, "us-west-2"]}
},
"Mappings": {
"NatGateway": {
"Condition": {
"B": "TwoNatGateways",
"C": "ThreeNatGateways"
}
}
},
"Resources": {
"VPC": {
"Type": "AWS::EC2::VPC",
"Properties": {"CidrBlock": "10.0.0.0/16"}
},
"PublicSubnetA": {
"Type": "AWS::EC2::Subnet",
"Properties": {
"VpcId": {"Ref": "VPC"},
"CidrBlock": "10.0.1.0/24",
"AvailabilityZone": {"Fn::Select": [0, {"Fn::GetAZs": ""}]}
}
},
"PublicSubnetB": {
"Type": "AWS::EC2::Subnet",
"Properties": {
"VpcId": {"Ref": "VPC"},
"CidrBlock": "10.0.2.0/24",
"AvailabilityZone": {"Fn::Select": [1, {"Fn::GetAZs": ""}]}
}
},
"PublicSubnetC": {
"Type": "AWS::EC2::Subnet",
"Properties": {
"VpcId": {"Ref": "VPC"},
"CidrBlock": "10.0.3.0/24",
"AvailabilityZone": {"Fn::Select": [2, {"Fn::GetAZs": ""}]}
}
},
"Fn::ForEach::NatGatewayAndEIP": [
"Identifier",
[ "A", "B", "C" ],
{
"NatGateway${Identifier}": {
"Type": "AWS::EC2::NatGateway",
"Properties": {
"AllocationId": {"Fn::GetAtt": [{"Fn::Sub": "NatGatewayAttachment${Identifier}"}, "AllocationId"]},
"SubnetId": {"Ref": {"Fn::Sub": "PublicSubnet${Identifier}"}}
},
"Condition": {"Fn::FindInMap": ["NatGateway", "Condition", {"Ref": "Identifier"}, {"DefaultValue": {"Ref": "AWS::NoValue"}}]}
},
"NatGatewayAttachment${Identifier}": {
"Type": "AWS::EC2::EIP",
"Properties": {
"Domain": "vpc"
},
"Condition": {"Fn::FindInMap": ["NatGateway", "Condition", {"Ref": "Identifier"}, {"DefaultValue": {"Ref": "AWS::NoValue"}}]}
}
}
]
}
}
```
### YAML
```
AWSTemplateFormatVersion: 2010-09-09
Transform: AWS::LanguageExtensions
Conditions:
TwoNatGateways: !Equals [!Ref "AWS::Region", "us-east-1"]
ThreeNatGateways: !Equals [!Ref "AWS::Region", "us-west-2"]
Mappings:
NatGateway:
Condition:
B: TwoNatGateways
C: ThreeNatGateways
Resources:
VPC:
Type: AWS::EC2::VPC
Properties:
CidrBlock: 10.0.0.0/16
PublicSubnetA:
Type: AWS::EC2::Subnet
Properties:
VpcId: !Ref VPC
CidrBlock: 10.0.1.0/24
AvailabilityZone: !Select [0, !GetAZs ""]
PublicSubnetB:
Type: AWS::EC2::Subnet
Properties:
VpcId: !Ref VPC
CidrBlock: 10.0.2.0/24
AvailabilityZone: !Select [1, !GetAZs ""]
PublicSubnetC:
Type: AWS::EC2::Subnet
Properties:
VpcId: !Ref VPC
CidrBlock: 10.0.3.0/24
AvailabilityZone: !Select [2, !GetAZs ""]
Fn::ForEach::NatGatewayAndEIP:
- Identifier
- - A
- B
- C
- NatGateway${Identifier}:
Type: AWS::EC2::NatGateway
Properties:
AllocationId: !GetAtt
- !Sub NatGatewayAttachment${Identifier}
- AllocationId
SubnetId: !Ref
Fn::Sub: PublicSubnet${Identifier}
Condition: !FindInMap
- NatGateway
- Condition
- !Ref Identifier
- DefaultValue: !Ref AWS::NoValue
NatGatewayAttachment${Identifier}:
Type: AWS::EC2::EIP
Properties:
Domain: vpc
Condition: !FindInMap
- NatGateway
- Condition
- !Ref Identifier
- DefaultValue: !Ref AWS::NoValue
```
The transformed template will be equivalent to the following template:
```
AWSTemplateFormatVersion: 2010-09-09
Transform: AWS::LanguageExtensions
Conditions:
TwoNatGateways: !Equals [!Ref "AWS::Region", "us-east-1"]
ThreeNatGateways: !Equals [!Ref "AWS::Region", "us-west-2"]
Resources:
VPC:
Type: AWS::EC2::VPC
Properties:
CidrBlock: 10.0.0.0/16
PublicSubnetA:
Type: AWS::EC2::Subnet
Properties:
VpcId: !Ref VPC
CidrBlock: 10.0.1.0/24
AvailabilityZone: !Select [0, !GetAZs ""]
PublicSubnetB:
Type: AWS::EC2::Subnet
Properties:
VpcId: !Ref VPC
CidrBlock: 10.0.2.0/24
AvailabilityZone: !Select [1, !GetAZs ""]
PublicSubnetC:
Type: AWS::EC2::Subnet
Properties:
VpcId: !Ref VPC
CidrBlock: 10.0.3.0/24
AvailabilityZone: !Select [2, !GetAZs ""]
NatGatewayA:
Type: AWS::EC2::NatGateway
Properties:
AllocationId: !GetAtt
- NatGatewayAttachmentA
- AllocationId
SubnetId: !Ref PublicSubnetA
NatGatewayB:
Type: AWS::EC2::NatGateway
Properties:
AllocationId: !GetAtt
- NatGatewayAttachmentB
- AllocationId
SubnetId: !Ref PublicSubnetB
Condition: TwoNatGateways
NatGatewayC:
Type: AWS::EC2::NatGateway
Properties:
AllocationId: !GetAtt
- NatGatewayAttachmentC
- AllocationId
SubnetId: !Ref PublicSubnetC
Condition: ThreeNatGateways
NatGatewayAttachmentA:
Type: AWS::EC2::EIP
Properties:
Domain: vpc
NatGatewayAttachmentB:
Type: AWS::EC2::EIP
Properties:
Domain: vpc
Condition: TwoNatGateways
NatGatewayAttachmentC:
Type: AWS::EC2::EIP
Properties:
Domain: vpc
Condition: ThreeNatGateways
```
## Replicate multiple resources using a nested `Fn::ForEach` loops
This example uses nested `Fn::ForEach` loops to map three resources ( [AWS::EC2::NetworkAcl](https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/aws-resource-ec2-natgateway.html), [AWS::EC2::Subnet](https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/aws-resource-ec2-subnet.html), and [AWS::EC2::SubnetNetworkAclAssociation](https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/aws-resource-ec2-subnetnetworkaclassociation.html)) with each other.
### JSON
```
{
"AWSTemplateFormatVersion": "2010-09-09",
"Transform": "AWS::LanguageExtensions",
"Resources": {
"VPC": {
"Type": "AWS::EC2::VPC",
"Properties": {
"CidrBlock": "10.0.0.0/16",
"EnableDnsSupport": "true",
"EnableDnsHostnames": "true"
}
},
"Fn::ForEach::SubnetResources": [
"Prefix",
[
"Transit",
"Public"
],
{
"Nacl${Prefix}Subnet": {
"Type": "AWS::EC2::NetworkAcl",
"Properties": {
"VpcId": {
"Ref": "VPC"
}
}
},
"Fn::ForEach::LoopInner": [
"Suffix",
[
"A",
"B",
"C"
],
{
"${Prefix}Subnet${Suffix}": {
"Type": "AWS::EC2::Subnet",
"Properties": {
"VpcId": {
"Ref": "VPC"
}
}
},
"Nacl${Prefix}Subnet${Suffix}Association": {
"Type": "AWS::EC2::SubnetNetworkAclAssociation",
"Properties": {
"SubnetId": {
"Ref": {
"Fn::Sub": "${Prefix}Subnet${Suffix}"
}
},
"NetworkAclId": {
"Ref": {
"Fn::Sub": "Nacl${Prefix}Subnet"
}
}
}
}
}
]
}
]
}
}
```
### YAML
```
AWSTemplateFormatVersion: 2010-09-09
Transform: AWS::LanguageExtensions
Resources:
VPC:
Type: AWS::EC2::VPC
Properties:
CidrBlock: 10.0.0.0/16
EnableDnsSupport: 'true'
EnableDnsHostnames: 'true'
'Fn::ForEach::SubnetResources':
- Prefix
- [Transit, Public]
- 'Nacl${Prefix}Subnet':
Type: AWS::EC2::NetworkAcl
Properties:
VpcId: !Ref 'VPC'
'Fn::ForEach::LoopInner':
- Suffix
- [A, B, C]
- '${Prefix}Subnet${Suffix}':
Type: AWS::EC2::Subnet
Properties:
VpcId: !Ref 'VPC'
'Nacl${Prefix}Subnet${Suffix}Association':
Type: AWS::EC2::SubnetNetworkAclAssociation
Properties:
SubnetId: !Ref
'Fn::Sub': '${Prefix}Subnet${Suffix}'
NetworkAclId: !Ref
'Fn::Sub': 'Nacl${Prefix}Subnet'
```
The transformed template will be equivalent to the following template:
```
AWSTemplateFormatVersion: 2010-09-09
Transform: AWS::LanguageExtensions
Resources:
VPC:
Type: AWS::EC2::VPC
Properties:
CidrBlock: 10.0.0.0/16
EnableDnsSupport: 'true'
EnableDnsHostnames: 'true'
NaclTransitSubnet:
Type: AWS::EC2::NetworkAcl
Properties:
VpcId: !Ref VPC
TransitSubnetA:
Type: AWS::EC2::Subnet
Properties:
VpcId: !Ref VPC
NaclTransitSubnetAAssociation:
Type: AWS::EC2::SubnetNetworkAclAssociation
Properties:
SubnetId: !Ref TransitSubnetA
NetworkAclId: !Ref NaclTransitSubnet
TransitSubnetB:
Type: AWS::EC2::Subnet
Properties:
VpcId: !Ref VPC
NaclTransitSubnetBAssociation:
Type: AWS::EC2::SubnetNetworkAclAssociation
Properties:
SubnetId: !Ref TransitSubnetB
NetworkAclId: !Ref NaclTransitSubnet
TransitSubnetC:
Type: AWS::EC2::Subnet
Properties:
VpcId: !Ref VPC
NaclTransitSubnetCAssociation:
Type: AWS::EC2::SubnetNetworkAclAssociation
Properties:
SubnetId: !Ref TransitSubnetC
NetworkAclId: !Ref NaclTransitSubnet
NaclPublicSubnet:
Type: AWS::EC2::NetworkAcl
Properties:
VpcId: !Ref VPC
PublicSubnetA:
Type: AWS::EC2::Subnet
Properties:
VpcId: !Ref VPC
NaclPublicSubnetAAssociation:
Type: AWS::EC2::SubnetNetworkAclAssociation
Properties:
SubnetId: !Ref PublicSubnetA
NetworkAclId: !Ref NaclPublicSubnet
PublicSubnetB:
Type: AWS::EC2::Subnet
Properties:
VpcId: !Ref VPC
NaclPublicSubnetBAssociation:
Type: AWS::EC2::SubnetNetworkAclAssociation
Properties:
SubnetId: !Ref PublicSubnetB
NetworkAclId: !Ref NaclPublicSubnet
PublicSubnetC:
Type: AWS::EC2::Subnet
Properties:
VpcId: !Ref VPC
NaclPublicSubnetCAssociation:
Type: AWS::EC2::SubnetNetworkAclAssociation
Properties:
SubnetId: !Ref PublicSubnetC
NetworkAclId: !Ref NaclPublicSubnet
```
## Reference replicated properties for an Amazon EC2 resource
This example uses the `Fn::ForEach` intrinsic function to reference replicated [AWS::EC2::Instance](https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/aws-resource-ec2-instance.html) resources.
### JSON
```
{
"AWSTemplateFormatVersion": "2010-09-09",
"Transform": "AWS::LanguageExtensions",
"Mappings": {
"Instances": {
"InstanceType": {
"B": "m5.4xlarge",
"C": "c5.2xlarge"
},
"ImageId": {"A": "ami-id1"}
}
},
"Resources": {
"Fn::ForEach::Instances": [
"Identifier",
[
"A",
"B",
"C"
],
{
"Instance${Identifier}": {
"Type": "AWS::EC2::Instance",
"Properties": {
"InstanceType": {"Fn::FindInMap": ["Instances", "InstanceType", {"Ref": "Identifier"}, {"DefaultValue": "m5.xlarge"}]},
"ImageId": {"Fn::FindInMap": ["Instances", "ImageId", {"Ref": "Identifier"}, {"DefaultValue": "ami-id-default"}]}
}
}
}
]
},
"Outputs": {
"SecondInstanceId": {
"Description": "Instance Id for InstanceB",
"Value": {"Ref": "InstanceB"}
},
"SecondPrivateIp": {
"Description": "Private IP for InstanceB",
"Value": {
"Fn::GetAtt": [
"InstanceB",
"PrivateIp"
]
}
}
}
}
```
### YAML
```
AWSTemplateFormatVersion: 2010-09-09
Transform: AWS::LanguageExtensions
Mappings:
Instances:
InstanceType:
B: m5.4xlarge
C: c5.2xlarge
ImageId:
A: ami-id1
Resources:
'Fn::ForEach::Instances':
- Identifier
- [A, B, C]
- 'Instance${Identifier}':
Type: AWS::EC2::Instance
Properties:
InstanceType: !FindInMap [Instances, InstanceType, !Ref 'Identifier', {DefaultValue: m5.xlarge}]
ImageId: !FindInMap [Instances, ImageId, !Ref 'Identifier', {DefaultValue: ami-id-default}]
Outputs:
SecondInstanceId:
Description: Instance Id for InstanceB
Value: !Ref 'InstanceB'
SecondPrivateIp:
Description: Private IP for InstanceB
Value: !GetAtt [InstanceB, PrivateIp]
```
The transformed template will be equivalent to the following template:
```
AWSTemplateFormatVersion: 2010-09-09
Transform: AWS::LanguageExtensions
Resources:
InstanceA:
Type: AWS::EC2::Instance
Properties:
InstanceType: m5.xlarge
ImageId: ami-id1
InstanceB:
Type: AWS::EC2::Instance
Properties:
InstanceType: m5.4xlarge
ImageId: ami-id-default
InstanceC:
Type: AWS::EC2::Instance
Properties:
InstanceType: c5.2xlarge
ImageId: ami-id-default
Outputs:
SecondInstanceId:
Description: Instance Id for InstanceB
Value: !Ref InstanceB
SecondPrivateIp:
Description: Private IP for InstanceB
Value: !GetAtt [InstanceB, PrivateIp]
```
## Replicate properties for an Amazon EC2 resource
This example uses the `Fn::ForEach` intrinsic function to repeat some properties like `ImageId`, `InstanceType`, and `AvailabilityZone` to an [AWS::EC2::Instance](https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/aws-resource-ec2-instance.html) resource.
### JSON
```
{
"AWSTemplateFormatVersion": "2010-09-09",
"Transform": "AWS::LanguageExtensions",
"Mappings": {
"InstanceA": {
"Properties": {
"ImageId": "ami-id1",
"InstanceType": "m5.xlarge"
}
},
"InstanceB": {
"Properties": {
"ImageId": "ami-id2"
}
},
"InstanceC": {
"Properties": {
"ImageId": "ami-id3",
"InstanceType": "m5.2xlarge",
"AvailabilityZone": "us-east-1a"
}
}
},
"Resources": {
"Fn::ForEach::Instances": [
"InstanceLogicalId",
[ "InstanceA", "InstanceB", "InstanceC" ],
{
"${InstanceLogicalId}": {
"Type": "AWS::EC2::Instance",
"Properties": {
"DisableApiTermination": true,
"UserData": {
"Fn::Base64": {
"Fn::Join": [
"",
[
"#!/bin/bash\n",
"yum update -y\n",
"yum install -y httpd.x86_64\n",
"systemctl start httpd.service\n",
"systemctl enable httpd.service\n",
"echo \"Hello World from $(hostname -f)\" > /var/www/html/index.html\n"
]
]
}
},
"Fn::ForEach::Properties": [
"PropertyName",
[ "ImageId", "InstanceType", "AvailabilityZone" ],
{
"${PropertyName}": {
"Fn::FindInMap": [
{ "Ref": "InstanceLogicalId" },
"Properties",
{ "Ref": "PropertyName"},
{
"DefaultValue": { "Ref": "AWS::NoValue" }
}
]
}
}
]
}
}
}
]
}
}
```
### YAML
```
AWSTemplateFormatVersion: 2010-09-09
Transform: AWS::LanguageExtensions
Mappings:
InstanceA:
Properties:
ImageId: ami-id1
InstanceType: m5.xlarge
InstanceB:
Properties:
ImageId: ami-id2
InstanceC:
Properties:
ImageId: ami-id3
InstanceType: m5.2xlarge
AvailabilityZone: us-east-1a
Resources:
'Fn::ForEach::Instances':
- InstanceLogicalId
- [InstanceA, InstanceB, InstanceC]
- '${InstanceLogicalId}':
Type: AWS::EC2::Instance
Properties:
DisableApiTermination: true
UserData:
Fn::Base64: !Sub |
#!/bin/bash
yum update -y
yum install -y httpd.x86_64
systemctl start httpd.service
systemctl enable httpd.service
echo "Hello World from $(hostname -f)" > /var/www/html/index.html
'Fn::ForEach::Properties':
- PropertyName
- [ImageId, InstanceType, AvailabilityZone]
- '${PropertyName}':
'Fn::FindInMap':
- Ref: 'InstanceLogicalId'
- Properties
- Ref: 'PropertyName'
- {DefaultValue: !Ref 'AWS::NoValue'}
```
The transformed template will be equivalent to the following template:
```
AWSTemplateFormatVersion: 2010-09-09
Transform: AWS::LanguageExtensions
Resources:
InstanceA:
Type: AWS::EC2::Instance
Properties:
DisableApiTermination: true
UserData:
Fn::Base64:
!Sub |
#!/bin/bash
yum update -y
yum install -y httpd.x86_64
systemctl start httpd.service
systemctl enable httpd.service
echo "Hello World from $(hostname -f)" > /var/www/html/index.html
ImageId: ami-id1
InstanceType: m5.xlarge
InstanceB:
Type: AWS::EC2::Instance
Properties:
DisableApiTermination: true
UserData:
Fn::Base64:
!Sub |
#!/bin/bash
yum update -y
yum install -y httpd.x86_64
systemctl start httpd.service
systemctl enable httpd.service
echo "Hello World from $(hostname -f)" > /var/www/html/index.html
ImageId: ami-id2
InstanceC:
Type: AWS::EC2::Instance
Properties:
DisableApiTermination: true
UserData:
Fn::Base64:
!Sub |
#!/bin/bash
yum update -y
yum install -y httpd.x86_64
systemctl start httpd.service
systemctl enable httpd.service
echo "Hello World from $(hostname -f)" > /var/www/html/index.html
ImageId: ami-id3
InstanceType: m5.2xlarge
AvailabilityZone: us-east-1a
```
## Passing non-alphanumeric characters within the `Collection` for `Fn::ForEach`
This example uses the `&{}` syntax, which allows the non-alphanumeric characters (`.` and `/`) in the IP addresses to be passed within the `Collection`.
### JSON
```
{
"AWSTemplateFormatVersion": "2010-09-09",
"Transform": "AWS::LanguageExtensions",
"Parameters": {
"IpAddresses": {
"Type": "CommaDelimitedList",
"Default": "10.0.2.0/24,10.0.3.0/24,10.0.4.0/24"
}
},
"Resources": {
"VPC": {
"Type": "AWS::EC2::VPC",
"Properties": {
"CidrBlock": "10.0.0.0/16",
"EnableDnsSupport": "true",
"EnableDnsHostnames": "true"
}
},
"Fn::ForEach::Subnets": [
"CIDR",
{
"Ref": "IpAddresses"
},
{
"Subnet&{CIDR}": {
"Type": "AWS::EC2::Subnet",
"Properties": {
"VpcId": {
"Ref": "VPC"
},
"CidrBlock": {
"Ref": "CIDR"
}
}
}
}
]
}
}
```
### YAML
```
AWSTemplateFormatVersion: 2010-09-09
Transform: AWS::LanguageExtensions
Parameters:
IpAddresses:
Type: CommaDelimitedList
Default: '10.0.2.0/24,10.0.3.0/24,10.0.4.0/24'
Resources:
VPC:
Type: AWS::EC2::VPC
Properties:
CidrBlock: 10.0.0.0/16
EnableDnsSupport: 'true'
EnableDnsHostnames: 'true'
'Fn::ForEach::Subnets':
- CIDR
- !Ref IpAddresses
- 'Subnet&{CIDR}':
Type: AWS::EC2::Subnet
Properties:
VpcId: !Ref VPC
CidrBlock: !Ref CIDR
```
The transformed template will be equivalent to the following template:
```
AWSTemplateFormatVersion: 2010-09-09
Transform: AWS::LanguageExtensions
Parameters:
IpAddresses:
Type: CommaDelimitedList
Default: '10.0.2.0/24,10.0.3.0/24,10.0.4.0/24'
Resources:
VPC:
Type: AWS::EC2::VPC
Properties:
CidrBlock: 10.0.0.0/16
EnableDnsSupport: 'true'
EnableDnsHostnames: 'true'
Subnet1002024:
Type: AWS::EC2::Subnet
Properties:
VpcId: !Ref VPC
CidrBlock: 10.0.2.0/24
Subnet1003024:
Type: AWS::EC2::Subnet
Properties:
VpcId: !Ref VPC
CidrBlock: 10.0.3.0/24
Subnet1004024:
Type: AWS::EC2::Subnet
Properties:
VpcId: !Ref VPC
CidrBlock: 10.0.4.0/24
```
# Examples of `Fn::ForEach` in the `Outputs` section
These examples demonstrate using the `Fn::ForEach` intrinsic function in the `Outputs` section. For more information about this section, see [Outputs](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/outputs-section-structure.html) in the *AWS CloudFormation User Guide*.
**Topics**
+ [Reference replicated `AWS::S3::Bucket` resources](#intrinsic-function-reference-foreach-example-replicate-outputs)
+ [Reference replicated `AWS::EC2::Instance` resources](#intrinsic-function-reference-foreach-example-replicate-conditions)
## Reference replicated `AWS::S3::Bucket` resources
This example uses nested `Fn::ForEach` loops in the `Outputs` section to reduce the template length.
### JSON
```
{
"AWSTemplateFormatVersion": "2010-09-09",
"Transform": "AWS::LanguageExtensions",
"Resources": {
"Fn::ForEach::Buckets": [
"Identifier",
[ "A", "B", "C" ],
{
"S3Bucket${Identifier}": {
"Type": "AWS::S3::Bucket",
"Properties": {
"AccessControl": "PublicRead",
"MetricsConfigurations": [
{
"Id": {"Fn::Sub": "EntireBucket${Identifier}"}
}
],
"WebsiteConfiguration": {
"IndexDocument": "index.html",
"ErrorDocument": "error.html",
"RoutingRules": [
{
"RoutingRuleCondition": {
"HttpErrorCodeReturnedEquals": "404",
"KeyPrefixEquals": "out1/"
},
"RedirectRule": {
"HostName": "ec2-11-22-333-44.compute-1.amazonaws.com",
"ReplaceKeyPrefixWith": "report-404/"
}
}
]
}
},
"DeletionPolicy": "Retain",
"UpdateReplacePolicy": "Retain"
}
}
]
},
"Outputs": {
"Fn::ForEach::BucketOutputs": [
"Identifier",
[ "A", "B", "C" ],
{
"Fn::ForEach::GetAttLoop": [
"Property",
[ "Arn", "DomainName", "WebsiteURL" ],
{
"S3Bucket${Identifier}${Property}": {
"Value": {"Fn::GetAtt": [{"Fn::Sub": "S3Bucket${Identifier}"}, {"Ref": "Property"}]}
}
}
]
}
]
}
}
```
### YAML
```
AWSTemplateFormatVersion: 2010-09-09
Transform: AWS::LanguageExtensions
Resources:
'Fn::ForEach::Buckets':
- Identifier
- [A, B, C]
- 'S3Bucket${Identifier}':
Type: AWS::S3::Bucket
Properties:
AccessControl: PublicRead
MetricsConfigurations:
- Id: !Sub 'EntireBucket${Identifier}'
WebsiteConfiguration:
IndexDocument: index.html
ErrorDocument: error.html
RoutingRules:
- RoutingRuleCondition:
HttpErrorCodeReturnedEquals: '404'
KeyPrefixEquals: out1/
RedirectRule:
HostName: ec2-11-22-333-44.compute-1.amazonaws.com
ReplaceKeyPrefixWith: report-404/
DeletionPolicy: Retain
UpdateReplacePolicy: Retain
Outputs:
'Fn::ForEach::BucketOutputs':
- Identifier
- [A, B, C]
- 'Fn::ForEach::GetAttLoop':
- Property
- [Arn, DomainName, WebsiteURL]
- 'S3Bucket${Identifier}${Property}':
Value: !GetAtt [!Sub 'S3Bucket${Identifier}', !Ref Property]
```
The transformed template will be equivalent to the following template:
```
AWSTemplateFormatVersion: 2010-09-09
Transform: AWS::LanguageExtensions
Resources:
S3BucketA:
Type: AWS::S3::Bucket
Properties:
AccessControl: PublicRead
MetricsConfigurations:
- Id: EntireBucketA
WebsiteConfiguration:
IndexDocument: index.html
ErrorDocument: error.html
RoutingRules:
- RoutingRuleCondition:
HttpErrorCodeReturnedEquals: '404'
KeyPrefixEquals: out1/
RedirectRule:
HostName: ec2-11-22-333-44.compute-1.amazonaws.com
ReplaceKeyPrefixWith: report-404/
DeletionPolicy: Retain
UpdateReplacePolicy: Retain
S3BucketB:
Type: AWS::S3::Bucket
Properties:
AccessControl: PublicRead
MetricsConfigurations:
- Id: EntireBucketB
WebsiteConfiguration:
IndexDocument: index.html
ErrorDocument: error.html
RoutingRules:
- RoutingRuleCondition:
HttpErrorCodeReturnedEquals: '404'
KeyPrefixEquals: out1/
RedirectRule:
HostName: ec2-11-22-333-44.compute-1.amazonaws.com
ReplaceKeyPrefixWith: report-404/
DeletionPolicy: Retain
UpdateReplacePolicy: Retain
S3BucketC:
Type: AWS::S3::Bucket
Properties:
AccessControl: PublicRead
MetricsConfigurations:
- Id: EntireBucketC
WebsiteConfiguration:
IndexDocument: index.html
ErrorDocument: error.html
RoutingRules:
- RoutingRuleCondition:
HttpErrorCodeReturnedEquals: '404'
KeyPrefixEquals: out1/
RedirectRule:
HostName: ec2-11-22-333-44.compute-1.amazonaws.com
ReplaceKeyPrefixWith: report-404/
DeletionPolicy: Retain
UpdateReplacePolicy: Retain
Outputs:
S3BucketAArn:
Value: !GetAtt [S3BucketA, Arn]
S3BucketADomainName:
Value: !GetAtt [S3BucketA, DomainName]
S3BucketAWebsiteURL:
Value: !GetAtt [S3BucketA, WebsiteURL]
S3BucketBArn:
Value: !GetAtt [S3BucketB, Arn]
S3BucketBDomainName:
Value: !GetAtt [S3BucketB, DomainName]
S3BucketBWebsiteURL:
Value: !GetAtt [S3BucketB, WebsiteURL]
S3BucketCArn:
Value: !GetAtt [S3BucketC, Arn]
S3BucketCDomainName:
Value: !GetAtt [S3BucketC, DomainName]
S3BucketCWebsiteURL:
Value: !GetAtt [S3BucketC, WebsiteURL]
```
## Reference replicated `AWS::EC2::Instance` resources
This example references replicated resources in the `Resources` section using the generated logical IDs.
### JSON
```
{
"AWSTemplateFormatVersion": "2010-09-09",
"Transform": "AWS::LanguageExtensions",
"Mappings": {
"Instances": {
"InstanceType": {
"B": "m5.4xlarge",
"C": "c5.2xlarge"
},
"ImageId": {"A": "ami-id1"}
}
},
"Resources": {
"Fn::ForEach::Instances": [
"Identifier",
[ "A", "B", "C" ],
{
"Instance${Identifier}": {
"Type": "AWS::EC2::Instance",
"Properties": {
"InstanceType": {"Fn::FindInMap": ["Instances", "InstanceType", {"Ref": "Identifier"}, {"DefaultValue": "m5.xlarge"}]},
"ImageId": {"Fn::FindInMap": ["Instances", "ImageId", {"Ref": "Identifier"}, {"DefaultValue": "ami-id-default"}]}
}
}
}
]
},
"Outputs": {
"SecondInstanceId": {
"Description": "Instance Id for InstanceB",
"Value": {"Ref": "InstanceB"}
},
"SecondPrivateIp": {
"Description": "Private IP for InstanceB",
"Value": {
"Fn::GetAtt": [
"InstanceB",
"PrivateIp"
]
}
}
}
}
```
### YAML
```
AWSTemplateFormatVersion: 2010-09-09
Transform: AWS::LanguageExtensions
Mappings:
Instances:
InstanceType:
B: m5.4xlarge
C: c5.2xlarge
ImageId:
A: ami-id1
Resources:
'Fn::ForEach::Instances':
- Identifier
- [A, B, C]
- 'Instance${Identifier}':
Type: AWS::EC2::Instance
Properties:
InstanceType: !FindInMap [Instances, InstanceType, !Ref Identifier, DefaultValue: m5.xlarge]
ImageId: !FindInMap [Instances, ImageId, !Ref Identifier, DefaultValue: ami-id-default]
Outputs:
SecondInstanceId:
Description: Instance Id for InstanceB
Value: !Ref InstanceB
SecondPrivateIp:
Description: Private IP for InstanceB
Value: !GetAtt [InstanceB, PrivateIp]
```
The transformed template will be equivalent to the following template:
```
AWSTemplateFormatVersion: 2010-09-09
Transform: AWS::LanguageExtensions
Resources:
InstanceA:
Type: AWS::EC2::Instance
Properties:
InstanceType: m5.xlarge
ImageId: ami-id1
InstanceB:
Type: AWS::EC2::Instance
Properties:
InstanceType: m5.4xlarge
ImageId: ami-id-default
InstanceC:
Type: AWS::EC2::Instance
Properties:
InstanceType: c5.2xlarge
ImageId: ami-id-default
Outputs:
SecondInstanceId:
Description: Instance Id for InstanceB
Value: !Ref InstanceB
SecondPrivateIp:
Description: Private IP for InstanceB
Value: !GetAtt [InstanceB, PrivateIp]
```
# Examples of `Fn::ForEach` in the `Conditions` section
These examples demonstrate using the `Fn::ForEach` intrinsic function in the `Conditions` section. For more information about this section, see [Conditions](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/conditions-section-structure.html) in the *AWS CloudFormation User Guide*.
**Important**
`Conditions` must be the second property listed, or later. Stack creation will fail if `Conditions` is the first property listed within the template fragment parameter of `Fn::ForEach`.
```
Resources:
'Fn::ForEach::Topics':
- LogicalId
- !Ref TopicList
- '${LogicalId}':
Condition: !Sub 'TopicCondition${LogicalId}'
Type: AWS::SNS::Topic
Properties:
TopicName: !Sub 'My${LogicalId}'
```
`Conditions` must be added as the second key, or later, for stack creation to succeed:
```
Resources:
'Fn::ForEach::Topics':
- LogicalId
- !Ref TopicList
- '${LogicalId}':
Type: AWS::SNS::Topic
Condition: !Sub 'TopicCondition${LogicalId}'
Properties:
TopicName: !Sub 'My${LogicalId}'
```
**Topics**
+ [Replicate a single condition](#intrinsic-function-reference-foreach-example-replicated-single-condition)
## Replicate a single condition
This example uses the `Fn::ForEach` intrinsic function in the `Conditions` section to replicate multiple similar conditions with different properties.
### JSON
```
{
"AWSTemplateFormatVersion": "2010-09-09",
"Transform": "AWS::LanguageExtensions",
"Parameters": {
"ParamA": {
"Type": "String",
"AllowedValues": [
"true",
"false"
]
},
"ParamB": {
"Type": "String",
"AllowedValues": [
"true",
"false"
]
},
"ParamC": {
"Type": "String",
"AllowedValues": [
"true",
"false"
]
},
"ParamD": {
"Type": "String",
"AllowedValues": [
"true",
"false"
]
}
},
"Conditions": {
"Fn::ForEach::CheckTrue": [
"Identifier",
["A", "B", "C", "D"],
{
"IsParam${Identifier}Enabled": {
"Fn::Equals": [
{"Ref": {"Fn::Sub": "Param${Identifier}"}},
"true"
]
}
}
]
},
"Resources": {
"WaitConditionHandle": {
"Type": "AWS::CloudFormation::WaitConditionHandle"
}
}
}
```
### YAML
```
AWSTemplateFormatVersion: 2010-09-09
Transform: AWS::LanguageExtensions
Parameters:
ParamA:
Type: String
AllowedValues:
- 'true'
- 'false'
ParamB:
Type: String
AllowedValues:
- 'true'
- 'false'
ParamC:
Type: String
AllowedValues:
- 'true'
- 'false'
ParamD:
Type: String
AllowedValues:
- 'true'
- 'false'
Conditions:
'Fn::ForEach::CheckTrue':
- Identifier
- [A, B, C, D]
- 'IsParam${Identifier}Enabled': !Equals
- !Ref
'Fn::Sub': 'Param${Identifier}'
- 'true'
Resources:
WaitConditionHandle:
Type: AWS::CloudFormation::WaitConditionHandle
```
The transformed template will be equivalent to the following template:
```
AWSTemplateFormatVersion: 2010-09-09
Parameters:
ParamA:
Type: String
AllowedValues:
- 'true'
- 'false'
ParamB:
Type: String
AllowedValues:
- 'true'
- 'false'
ParamC:
Type: String
AllowedValues:
- 'true'
- 'false'
ParamD:
Type: String
AllowedValues:
- 'true'
- 'false'
Conditions:
IsParamAEnabled: !Equals
- !Ref ParamA
- 'true'
IsParamBEnabled: !Equals
- !Ref ParamB
- 'true'
IsParamCEnabled: !Equals
- !Ref ParamC
- 'true'
IsParamDEnabled: !Equals
- !Ref ParamD
- 'true'
Resources:
WaitConditionHandle:
Type: AWS::CloudFormation::WaitConditionHandle
```