# General template snippets
<a name="quickref-general"></a>

The following examples show different CloudFormation template features that aren't specific to an AWS service.

**Topics**
+ [

## Base64 encoded UserData property
](#scenario-userdata-base64)
+ [

## Base64 encoded UserData property with AccessKey and SecretKey
](#scenario-userdata-base64-with-keys)
+ [

## Parameters section with one literal string parameter
](#scenario-one-string-parameter)
+ [

## Parameters section with string parameter with regular expression constraint
](#scenario-constraint-string-parameter)
+ [

## Parameters section with number parameter with MinValue and MaxValue constraints
](#scenario-one-number-min-parameter)
+ [

## Parameters section with number parameter with AllowedValues constraint
](#scenario-one-number-parameter)
+ [

## Parameters section with one literal CommaDelimitedList parameter
](#scenario-one-list-parameter)
+ [

## Parameters section with parameter value based on pseudo parameter
](#scenario-one-pseudo-parameter)
+ [

## Mapping section with three mappings
](#scenario-mapping-with-four-maps)
+ [

## Description based on literal string
](#scenario-description-from-literal-string)
+ [

## Outputs section with one literal string output
](#scenario-output-with-literal-string)
+ [

## Outputs section with one resource reference and one pseudo reference output
](#scenario-output-with-ref-and-pseudo-ref)
+ [

## Outputs section with an output based on a function, a literal string, a reference, and a pseudo parameter
](#scenario-output-with-complex-spec)
+ [

## Template format version
](#scenario-format-version)
+ [

## AWS Tags property
](#scenario-format-aws-tag)

## Base64 encoded UserData property
<a name="scenario-userdata-base64"></a>

This example shows the assembly of a `UserData` property using the `Fn::Base64` and `Fn::Join` functions. The references `MyValue` and `MyName` are parameters that must be defined in the `Parameters` section of the template. The literal string `Hello World` is just another value this example passes in as part of the `UserData`.

### JSON
<a name="quickref-general-example-1.json"></a>

```
1. "UserData" : {
2.     "Fn::Base64" : {
3.         "Fn::Join" : [ ",", [
4.             { "Ref" : "MyValue" },
5.             { "Ref" : "MyName" },
6.             "Hello World" ] ]
7.     }
8. }
```

### YAML
<a name="quickref-general-example-1.yaml"></a>

```
1. UserData:
2.   Fn::Base64: !Sub |
3.      Ref: MyValue
4.      Ref: MyName
5.      Hello World
```

## Base64 encoded UserData property with AccessKey and SecretKey
<a name="scenario-userdata-base64-with-keys"></a>

This example shows the assembly of a `UserData` property using the `Fn::Base64` and `Fn::Join` functions. It includes the `AccessKey` and `SecretKey` information. The references `AccessKey` and `SecretKey` are parameters that must be defined in the Parameters section of the template.

### JSON
<a name="quickref-general-example-2.json"></a>

```
1. "UserData" : {
2.     "Fn::Base64" : {
3.         "Fn::Join" : [ "", [
4.             "ACCESS_KEY=", { "Ref" : "AccessKey" },
5.             "SECRET_KEY=", { "Ref" : "SecretKey" } ]
6.         ]
7.     }
8. }
```

### YAML
<a name="quickref-general-example-2.yaml"></a>

```
1. UserData:
2.   Fn::Base64: !Sub |
3.      ACCESS_KEY=${AccessKey}
4.      SECRET_KEY=${SecretKey}
```

## Parameters section with one literal string parameter
<a name="scenario-one-string-parameter"></a>

The following example depicts a valid Parameters section declaration in which a single `String` type parameter is declared.

### JSON
<a name="quickref-general-example-3.json"></a>

```
1. "Parameters" : {
2.     "UserName" : {
3.         "Type" : "String",
4.         "Default" : "nonadmin",
5.         "Description" : "Assume a vanilla user if no command-line spec provided"
6.     }
7. }
```

### YAML
<a name="quickref-general-example-3.yaml"></a>

```
1. Parameters:
2.   UserName:
3.     Type: String
4.     Default: nonadmin
5.     Description: Assume a vanilla user if no command-line spec provided
```

## Parameters section with string parameter with regular expression constraint
<a name="scenario-constraint-string-parameter"></a>

The following example depicts a valid Parameters section declaration in which a single `String` type parameter is declared. The `AdminUserAccount` parameter has a default of `admin`. The parameter value must have a minimum length of 1, a maximum length of 16, and contains alphabetical characters and numbers but must begin with an alphabetical character.

### JSON
<a name="quickref-general-example-4.json"></a>

```
 1. "Parameters" : {
 2.     "AdminUserAccount": {
 3.       "Default": "admin",
 4.       "NoEcho": "true",
 5.       "Description" : "The admin account user name",
 6.       "Type": "String",
 7.       "MinLength": "1",
 8.       "MaxLength": "16",
 9.       "AllowedPattern" : "[a-zA-Z][a-zA-Z0-9]*"
10.     }
11. }
```

### YAML
<a name="quickref-general-example-4.yaml"></a>

```
1. Parameters:
2.   AdminUserAccount:
3.     Default: admin
4.     NoEcho: true
5.     Description: The admin account user name
6.     Type: String
7.     MinLength: 1
8.     MaxLength: 16
9.     AllowedPattern: '[a-zA-Z][a-zA-Z0-9]*'
```

## Parameters section with number parameter with MinValue and MaxValue constraints
<a name="scenario-one-number-min-parameter"></a>

The following example depicts a valid Parameters section declaration in which a single `Number` type parameter is declared. The `WebServerPort` parameter has a default of 80 and a minimum value 1 and maximum value 65535.

### JSON
<a name="quickref-general-example-5.json"></a>

```
1. "Parameters" : {
2.     "WebServerPort": {
3.       "Default": "80",
4.       "Description" : "TCP/IP port for the web server",
5.       "Type": "Number",
6.       "MinValue": "1",
7.       "MaxValue": "65535"
8.     }
9. }
```

### YAML
<a name="quickref-general-example-5.yaml"></a>

```
1. Parameters:
2.   WebServerPort:
3.     Default: 80
4.     Description: TCP/IP port for the web server
5.     Type: Number
6.     MinValue: 1
7.     MaxValue: 65535
```

## Parameters section with number parameter with AllowedValues constraint
<a name="scenario-one-number-parameter"></a>

The following example depicts a valid Parameters section declaration in which a single `Number` type parameter is declared. The `WebServerPort` parameter has a default of 80 and allows only values of 80 and 8888.

### JSON
<a name="quickref-general-example-6.json"></a>

```
1. "Parameters" : {
2.     "WebServerPortLimited": {
3.       "Default": "80",
4.       "Description" : "TCP/IP port for the web server",
5.       "Type": "Number",
6.       "AllowedValues" : ["80", "8888"]
7.     }
8. }
```

### YAML
<a name="quickref-general-example-6.yaml"></a>

```
1. Parameters:
2.   WebServerPortLimited:
3.     Default: 80
4.     Description: TCP/IP port for the web server
5.     Type: Number
6.     AllowedValues:
7.     - 80
8.     - 8888
```

## Parameters section with one literal CommaDelimitedList parameter
<a name="scenario-one-list-parameter"></a>

The following example depicts a valid `Parameters` section declaration in which a single `CommaDelimitedList` type parameter is declared. The `NoEcho` property is set to `TRUE`, which will mask its value with asterisks (\$1\$1\$1\$1\$1) in the **describe-stacks** output, except for information stored in the locations specified below.

**Important**  
Using the `NoEcho` attribute does not mask any information stored in the following:  
The `Metadata` template section. CloudFormation does not transform, modify, or redact any information you include in the `Metadata` section. For more information, see [Metadata](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/metadata-section-structure.html).
The `Outputs` template section. For more information, see [Outputs](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/outputs-section-structure.html).
The `Metadata` attribute of a resource definition. For more information, see [`Metadata` attribute](https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/aws-attribute-metadata.html).
We strongly recommend you do not use these mechanisms to include sensitive information, such as passwords or secrets.

**Important**  
Rather than embedding sensitive information directly in your CloudFormation templates, we recommend you use dynamic parameters in the stack template to reference sensitive information that is stored and managed outside of CloudFormation, such as in the AWS Systems Manager Parameter Store or AWS Secrets Manager.  
For more information, see the [Do not embed credentials in your templates](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/security-best-practices.html#creds) best practice.

### JSON
<a name="quickref-general-example-7.json"></a>

```
1. "Parameters" : {
2.     "UserRoles" : {
3.         "Type" : "CommaDelimitedList",
4.         "Default" : "guest,newhire",
5.         "NoEcho" : "TRUE"
6.     }
7. }
```

### YAML
<a name="quickref-general-example-7.yaml"></a>

```
1. Parameters:
2.   UserRoles:
3.     Type: CommaDelimitedList
4.     Default: "guest,newhire"
5.     NoEcho: true
```

## Parameters section with parameter value based on pseudo parameter
<a name="scenario-one-pseudo-parameter"></a>

The following example shows commands in the EC2 user data that use the pseudo parameters `AWS::StackName` and `AWS::Region`. For more information about pseudo parameters, see [Get AWS values using pseudo parameters](pseudo-parameter-reference.md).

### JSON
<a name="quickref-general-example-10.json"></a>

```
 1.           "UserData"       : { "Fn::Base64" : { "Fn::Join" : ["", [
 2.              "#!/bin/bash -xe\n",
 3.              "yum install -y aws-cfn-bootstrap\n",
 4. 
 5.              "/opt/aws/bin/cfn-init -v ",
 6.              "         --stack ", { "Ref" : "AWS::StackName" },
 7.              "         --resource LaunchConfig ",
 8.              "         --region ", { "Ref" : "AWS::Region" }, "\n",
 9. 
10.              "/opt/aws/bin/cfn-signal -e $? ",
11.              "         --stack ", { "Ref" : "AWS::StackName" },
12.              "         --resource WebServerGroup ",
13.              "         --region ", { "Ref" : "AWS::Region" }, "\n"
14.         ]]}}
15.       }
```

### YAML
<a name="quickref-general-example-10.yaml"></a>

```
1. UserData:
2.   Fn::Base64: !Sub |
3.      #!/bin/bash -xe
4.      yum update -y aws-cfn-bootstrap
5.      /opt/aws/bin/cfn-init -v --stack ${AWS::StackName} --resource LaunchConfig --region ${AWS::Region}
6.      /opt/aws/bin/cfn-signal -e $? --stack ${AWS::StackName} --resource WebServerGroup --region ${AWS::Region}
```

## Mapping section with three mappings
<a name="scenario-mapping-with-four-maps"></a>

The following example depicts a valid `Mapping` section declaration that contains three mappings. The map, when matched with a mapping key of `Stop`, `SlowDown`, or `Go`, provides the RGB values assigned to the corresponding `RGBColor` attribute.

### JSON
<a name="quickref-general-example-11.json"></a>

```
 1. "Mappings" : {
 2.     "LightColor" : {
 3.         "Stop" : {
 4.             "Description" : "red",
 5.             "RGBColor" : "RED 255 GREEN 0 BLUE 0"
 6.         },
 7.         "SlowDown" : {
 8.             "Description" : "yellow",
 9.             "RGBColor" : "RED 255 GREEN 255 BLUE 0"
10.         },
11.         "Go" : {
12.             "Description" : "green",
13.             "RGBColor" : "RED 0 GREEN 128 BLUE 0"
14.         }
15.     }
16. }
```

### YAML
<a name="quickref-general-example-11.yaml"></a>

```
 1. Mappings:
 2.   LightColor:
 3.     Stop:
 4.       Description: red
 5.       RGBColor: "RED 255 GREEN 0 BLUE 0"
 6.     SlowDown:
 7.       Description: yellow
 8.       RGBColor: "RED 255 GREEN 255 BLUE 0"
 9.     Go:
10.       Description: green
11.       RGBColor: "RED 0 GREEN 128 BLUE 0"
```

## Description based on literal string
<a name="scenario-description-from-literal-string"></a>

The following example depicts a valid `Description` section declaration where the value is based on a literal string. This snippet can be for templates, parameters, resources, properties, or outputs.

### JSON
<a name="quickref-general-example-8.json"></a>

```
1. "Description" : "Replace this value"
```

### YAML
<a name="quickref-general-example-8.yaml"></a>

```
1. Description: "Replace this value"
```

## Outputs section with one literal string output
<a name="scenario-output-with-literal-string"></a>

This example shows a output assignment based on a literal string.

### JSON
<a name="quickref-general-example-12.json"></a>

```
1. "Outputs" : {
2.     "MyPhone" : {
3.         "Value" : "Please call 555-5555",
4.         "Description" : "A random message for aws cloudformation describe-stacks"
5.     }
6. }
```

### YAML
<a name="quickref-general-example-12.yaml"></a>

```
1. Outputs:
2.   MyPhone:
3.     Value: Please call 555-5555
4.     Description: A random message for aws cloudformation describe-stacks
```

## Outputs section with one resource reference and one pseudo reference output
<a name="scenario-output-with-ref-and-pseudo-ref"></a>

This example shows an `Outputs` section with two output assignments. One is based on a resource, and the other is based on a pseudo reference.

### JSON
<a name="quickref-general-example-13.json"></a>

```
1. "Outputs" : {
2.    "SNSTopic" : { "Value" : { "Ref" : "MyNotificationTopic" } },
3.    "StackName" : { "Value" : { "Ref" : "AWS::StackName" } }
4. }
```

### YAML
<a name="quickref-general-example-13.yaml"></a>

```
1. Outputs:
2.   SNSTopic:
3.     Value: !Ref MyNotificationTopic
4.   StackName:
5.     Value: !Ref AWS::StackName
```

## Outputs section with an output based on a function, a literal string, a reference, and a pseudo parameter
<a name="scenario-output-with-complex-spec"></a>

This example shows an Outputs section with one output assignment. The Join function is used to concatenate the value, using a percent sign as the delimiter.

### JSON
<a name="quickref-general-example-14.json"></a>

```
1. "Outputs" : {
2.     "MyOutput" : {
3.         "Value" : { "Fn::Join" :
4.             [ "%", [ "A-string", {"Ref" : "AWS::StackName" } ] ]
5.         }
6.     }
7. }
```

### YAML
<a name="quickref-general-example-14.yaml"></a>

```
1. Outputs:
2.   MyOutput:
3.     Value: !Join [ %, [ 'A-string', !Ref 'AWS::StackName' ]]
```

## Template format version
<a name="scenario-format-version"></a>

The following snippet depicts a valid `AWSTemplateFormatVersion` section declaration.

### JSON
<a name="quickref-general-example-9.json"></a>

```
1. "AWSTemplateFormatVersion" : "2010-09-09"
```

### YAML
<a name="quickref-general-example-9.yaml"></a>

```
1. AWSTemplateFormatVersion: '2010-09-09'
```

## AWS Tags property
<a name="scenario-format-aws-tag"></a>

This example shows an AWS `Tags` property. You would specify this property within the Properties section of a resource. When the resource is created, it will be tagged with the tags you declare.

### JSON
<a name="quickref-general-example-15.json"></a>

```
 1. "Tags" : [
 2.       {
 3.         "Key" : "keyname1",
 4.         "Value" : "value1"
 5.       },
 6.       {
 7.         "Key" : "keyname2",
 8.         "Value" : "value2"
 9.       }
10.     ]
```

### YAML
<a name="quickref-general-example-15.yaml"></a>

```
1. Tags: 
2.   - 
3.     Key: "keyname1"
4.     Value: "value1"
5.   - 
6.     Key: "keyname2"
7.     Value: "value2"
```