AWS CloudFormationIntrinsic Functions and Mappings

Managing Windows instances in the Cloud

Sponsors

Presented by Adam Book from

Find me on LinkedIn

CloudFormation Deep Dive

CloudFormation Review

AWS CloudFormation Allows you to build Infrastructure as code using templates which are constructed from json.

CloudFormation Template

There are 8 sections of a Cloud formation template, most of which are optional

Format Version (optional)

Description (optional)

Metadata (optional)

Mappings (optional)

Parameters(optional)

Conditions(optional)

Resources (required)

Outputs(optional)

CloudFormation Best Practice

For more infohttp://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/best-practices.html

As you use Cloud Formation make sure you follow the best practices for success

• Do Not Embed Credentials in You Templates• Use AWS-Specific Parameter Types• Use Parameter Constraints • Validate Templates Before Using them • Manage All Stack Resources Through AWS Cloud Formation

CloudFormationIntrinsic FunctionsFunction OverviewFn::Base64 returns the Base64 representation of the input string (user data)

Fn::FindInMap returns the value corresponding to keys in a two-level map that is declared in the Mappings section

Fn::GetAtt returns the value of an attribute from a resource in the template.

Fn::GetAZs returns an array that lists Availability Zones for a specified region.

Fn::Join appends a set of values into a single value, separated by the specified delimiter.

Fn::Select returns a single object from a list of objects by index.

Ref returns the value of the specified parameter or resource.

CloudFormationMappings

The Mappings section is optional but is matches a key to a corresponding set of named values. If you want to set values based on region, you can create a mapping that uses the key as the name and then contains the values you want to specify for each region.

You cannot include parameters, pseudo parameters, or intrinsic functions in the Mappings section.

CloudFormationMappings - cont. "Mappings" : { "RegionMap" : { "us-east-1" : { "32" : "ami-6411e20d"}, "us-west-1" : { "32" : "ami-c9c7978c"}, "eu-west-1" : { "32" : "ami-37c2f643"}, "ap-southeast-1" : { "32" : "ami-66f28c34"}, "ap-northeast-1" : { "32" : "ami-9c03a89d"} } }

CloudFormationMappings - cont. "asgApp": { "MinSize" : { "value": "2" }, "MaxSize" : { "value": "2" }, "DesiredCapacity" : { "value": "2" }, "HealthCheckType" : { "value": "EC2" }, "TerminationPolicies" : { "value": "OldestInstance" } }

CloudFormationMappings - cont.

"asgAppA": { "Type": "AWS::AutoScaling::AutoScalingGroup", "Properties": { "AvailabilityZones" : { "Ref": "AZs" }, "VPCZoneIdentifier" : { "Ref": "PrivateAPPSubnets" }, "LaunchConfigurationName" : { "Ref": "LaunchConfig" }, "MinSize" : { "Fn::FindInMap": [ "asgApp", "MinSize", "value" ] }, "MaxSize" : { "Fn::FindInMap": [ "asgApp", "MaxSize", "value" ] }, "DesiredCapacity" : { "Fn::FindInMap": [ "asgApp", "DesiredCapacity", "value" ] }, "HealthCheckType" : { "Fn::FindInMap": [ "asgApp", "HealthCheckType", "value" ] }, "TerminationPolicies" : [{ "Fn::FindInMap": [ "asgApp", "TerminationPolicies", "value" ] }],

Fn::FindInMap

"Resources" : { "myEC2Instance" : { "Type" : "AWS::EC2::Instance", "Properties" : { "ImageId" : { "Fn::FindInMap" : [ "RegionMap", { "Ref" : "AWS::Region" }, "32"]}, "InstanceType" : "m1.small" } } } }

This function performs lookups, it accepts a ‘mappings’ object on of one or two keys and then returns a value

For more infohttp://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/intrinsic-function-reference-findinmap.html

Fn::Base64

{ "Fn::Base64" : ”apt-get update –y " }

This function accepts plain text and converts it to Base 64

For more infohttp://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/intrinsic-function-reference-base64.html

Fn::Join

"Outputs" : { "URL" : { "Description" : "The URL of your demo website", "Value" : { "Fn::Join" : [ "", [ "http://", { "Fn::GetAtt" : [ "ElasticLoadBalancer", "DNSName" ]}]]} } }

This can be used to concatenate various components to produce things such as a URL.

For more infohttp://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/intrinsic-function-reference-join.html

Fn::GetAtt

Some examples of attributes that can be called are:• EC2 -> PrivateIp• EC2-> PublicIp• ElasticLoadBalancing -> DNSName• IAM::Group -> ARN • S3 Bucket -> DomainName • Simple AD -> Alias

As you dynamically create items in your Cloud Formation templates , you may need to use some of the Attributes after they are created.

For more infohttp://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/intrinsic-function-reference-getatt.html

Fn::GetAtt

"MyEIP" : { "Type" : "AWS::EC2::EIP", "Properties" : { "InstanceId" : { "Ref" : "MyEC2Instance" } } }

“Fn:GetAtt” :[ “MyEIP”, “AllocationId” ]

As you dynamically create items in your Cloud Formation templates

For more infohttp://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/intrinsic-function-reference-getatt.html

Fn::GetAZs

{ "Fn::GetAZs" : "us-east-1" }

{ "Fn::GetAZs" : { "Ref" : "AWS::Region" } }

The intrinsic function Ref returns to value of the specified parameter or resource.

For more infohttp://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/intrinsic-function-reference-select.html

NOTE: You can use the Ref function in the Fn::GetAZz function.

Fn::Select

{ “Fn::Select” : [ “0”, {”Fn::GetAZs” : “”} ] }

Selects a single object from a list of object and can be paired with other functions such as Fn::GetAZs

For more infohttp://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/intrinsic-function-reference-select.html

The output is the first Availablity zone in the region where the template is applied.

Replacing the 0 with a 1 would select the second Availability Zone

Fn::Ref

"MyEIP" : { "Type" : "AWS::EC2::EIP", "Properties" : { "InstanceId" : { "Ref" : "MyEC2Instance" } } }

The intrinsic function Ref returns to value of the specified parameter or resource.

For more infohttp://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/intrinsic-function-reference-ref.html

Cloud Formation Templates Real World Examples

Photo curtesyof Stephen Radford via http://snap.io

Questions?

Image by http://www.gratisography.com/