Module 14 - CloudFormation

AWS CloudFormation

AWS CloudFormation is a service that helps you model and set up your AWS resources so that you can spend less time managing those resources and more time focusing on your applications that run in AWS.
You create a template that describes all the AWS resources that you want (like Amazon EC2 instances or Amazon RDS DB instances), and CloudFormation takes care of provisioning and configuring those resources for you.
You don't need to individually create and configure AWS resources and figure out what's dependent on what; CloudFormation handles that.

Benefits

Deployment speed
Scaling up
Service integration
Consistency
Security
Easy updates

CloudFormation Concepts

When you use AWS CloudFormation, you work with templates and stacks. You create templates to describe your AWS resources and their properties.

Templates
Stacks
Change sets

Templates

A CloudFormation template is a JSON or YAML formatted text file.
You can save these files with any extension, such as .json, .yaml, .template, or .txt.
CloudFormation uses these templates as blueprints for building your AWS resources. For example, in a template, you can describe an Amazon EC2 instance, such as the instance type, the AMI ID, block device mappings, and its Amazon EC2 key pair name.
Whenever you create a stack, you also specify a template that CloudFormation uses to create whatever you described in the template.

Example Template format

AWSTemplateFormatVersion: 2010-09-09
Description: A sample template
Resources:
  MyEC2Instance:
    Type: 'AWS::EC2::Instance'
    Properties:
      ImageId: ami-0ff8a91507f77f867
      InstanceType: t2.micro
      KeyName: testkey
      BlockDeviceMappings:
        - DeviceName: /dev/sdm
          Ebs:
            VolumeType: io1
            Iops: 200
            DeleteOnTermination: false
            VolumeSize: 20

Stacks

When you use CloudFormation, you manage related resources as a single unit called a stack.
You create, update, and delete a collection of resources by creating, updating, and deleting stacks.
All the resources in a stack are defined by the stack's CloudFormation template.
Suppose you created a template that includes an Auto Scaling group, Elastic Load Balancing load balancer, and an Amazon Relational Database Service (Amazon RDS) database instance.
To create those resources, you create a stack by submitting the template that you created, and CloudFormation provisions all those resources for you.

Change sets

If you need to make changes to the running resources in a stack, you update the stack.
Before making changes to your resources, you can generate a change set, which is a summary of your proposed changes.
Change sets allow you to see how your changes might impact your running resources, especially for critical resources, before implementing them.

Example

if you change the name of an Amazon RDS database instance, CloudFormation will create a new database and delete the old one.
You will lose the data in the old database unless you've already backed it up.
If you generate a change set, you will see that your change will cause your database to be replaced, and you will be able to plan accordingly before you update your stack.

How does cloudformation works

When creating a stack, AWS CloudFormation makes underlying service calls to AWS to provision and configure your resources.
CloudFormation can only perform actions that you have permission to do.
For example, to create EC2 instances by using CloudFormation, you need permissions to create instances.
You'll need similar permissions to terminate instances when you delete stacks with instances.
You use AWS Identity and Access Management (IAM) to manage permissions.
The calls that CloudFormation makes are all declared by your template.

Template Anatomy

A template is a JSON- or YAML-formatted text file that describes your AWS infrastructure.

AWSTemplateFormatVersion: "version date"

Description:
  String

Metadata:
  template metadata

Parameters:
  set of parameters

Rules:
  set of rules

Mappings:
  set of mappings

Conditions:
  set of conditions

Transform:
  set of transforms

Resources:
  set of resources

Outputs:
  set of outputs

Format Version

The AWSTemplateFormatVersion section (optional) identifies the capabilities of the template. The latest template format version is 2010-09-09 and is currently the only valid value.

JSON

"AWSTemplateFormatVersion" : "2010-09-09"

YAML

AWSTemplateFormatVersion: "2010-09-09"

Description

The Description section (optional) enables you to include comments about your template.
The value for the description declaration must be a literal string that is between 0 and 1024 bytes in length

JSON

"Description" : "Here are some details about the template."

YAML

Description: > Here are some details about the template.

Metadata

You can use the optional Metadata section to include arbitrary JSON or YAML objects that provide details about the template.

JSON

"Metadata" : {
  "Instances" : {"Description" : "Information about the instances"},
  "Databases" : {"Description" : "Information about the databases"}
}

YAML

Metadata:
  Instances:
    Description: "Information about the instances"
  Databases: 
    Description: "Information about the databases"

Meta keys

AWS::CloudFormation::Init
AWS::CloudFormation::Interface
AWS::CloudFormation::Designer

Parameters

Use the optional Parameters section to customize your templates. Parameters enable you to input custom values to your template each time you create or update a stack.

Example

declare a parameter named InstanceTypeParameter. This parameter lets you specify the Amazon EC2 instance type for the stack to use when you create or update the stack. Note that InstanceTypeParameter has a default value of t2.micro.

JSON

"Parameters" : {
  "ParameterLogicalID" : {
    "Type" : "DataType",
    "ParameterProperty" : "value"
  }
}

YAML

Parameters:
  ParameterLogicalID:
    Type: DataType
    ParameterProperty: value

Rules

The optional Rules section validates a parameter or a combination of parameters passed to a template during a stack creation or stack update. To use template rules, explicitly declare Rules in your template followed by an assertion.
A rule can include a RuleCondition property and must include an Assertions property.

Rule specific intrinsic functions

To define a rule condition and assertions, use rule-specific intrinsic functions, which are functions that can only be used in the Rules section of a template. You can nest functions, but the final result of a rule condition or assertion must be either true or false.

Fn::And
Fn::Contains
Fn::EachMemberEquals
Fn::EachMemberIn
Fn::Equals
Fn::If
Fn::Not
Fn::Or
Fn::RefAll
Fn::ValueOf
Fn::ValueOfAll

Mappings

The optional Mappings section matches a key to a corresponding set of named values.
For example, if you want to set values based on a region, you can create a mapping that uses the region name as a key and contains the values you want to specify for each specific region. You use the Fn::FindInMap intrinsic function to retrieve values in a map.

JSON

"Mappings" : {
  "Mapping01" : {
    "Key01" : {
      "Name" : "Value01"
    },
    "Key02" : {
      "Name" : "Value02"
    },
    "Key03" : {
      "Name" : "Value03"
    }
  }
}

YAML

Mappings: 
  Mapping01: 
    Key01: 
      Name: Value01
    Key02: 
      Name: Value02
    Key03: 
      Name: Value03

Conditions

The optional Conditions section contains statements that define the circumstances under which entities are created or configured.
For example, you can create a condition and then associate it with a resource or output so that AWS CloudFormation only creates the resource or output if the condition is true.

JSON

"Conditions" : {
  "Logical ID" : {Intrinsic function}
}

YAML

Conditions:
  Logical ID:
    Intrinsic function

Transform

The optional Transform section specifies one or more macros that AWS CloudFormation uses to process your template. The Transform section builds on the simple, declarative language of AWS CloudFormation with a powerful macro system.
You can declare one or more macros within a template. AWS CloudFormation executes macros in the order that they're specified.
When you create a change set, AWS CloudFormation generates a change set that includes the processed template content. You can then review the changes and execute the change set.
```
Transform:
  - MyMacro
  - 'AWS::Serverless'
```

Resources

The required Resources section declares the AWS resources that you want to include in the stack, such as an Amazon EC2 instance or an Amazon S3 bucket.

JSON

"Resources" : {
    "Logical ID" : {
        "Type" : "Resource type",
        "Properties" : {
            Set of properties
        }
    }
}

YAML

Resources:
  Logical ID:
    Type: Resource type
    Properties:
      Set of properties

Output

The optional Outputs section declares output values that you can import into other stacks (to create cross-stack references), return in response (to describe stack calls), or view on the AWS CloudFormation console.

JSON

"Outputs" : {
  "Logical ID" : {
    "Description" : "Information about the value",
    "Value" : "Value to return",
    "Export" : {
      "Name" : "Name of resource to export"
    }
  }
}

YAML

Outputs:
  Logical ID:
    Description: Information about the value
    Value: Value to return
    Export:
      Name: Name of resource to export

AWS Cloudformation Designer

AWS CloudFormation Designer (Designer) is a graphic tool for creating, viewing, and modifying AWS CloudFormation templates.
With Designer, you can diagram your template resources using a drag-and-drop interface, and then edit their details using the integrated JSON and YAML editor.
Whether you are a new or an experienced AWS CloudFormation user, AWS CloudFormation Designer can help you quickly see the interrelationship between a template's resources and easily modify templates.

Benefits

Visualize template resources
Simplify template authoring
Simplify editing with the integrated JSON and YAML editor

Desginer Overview

How to create Cloudformation

Click create stack and give all details select template type.
Choose our JSON or YAML file otherwise also create template using designer
Give source details is S3 url or Local file and click next.

Step 2: In this step we can give stack name and check all our configuration and click next

Step 3: Specify stack details

This step attach a IAM role and leave other options by default.

Step 4: Review our configuration and click create.

+ All of our resources are created as a stack we can change and delete using the stack.

Pricing

There is no additional charge for using AWS CloudFormation with resource providers in the following namespaces: AWS::, Alexa::, and Custom::*. In these cases, you pay for AWS resources such as Amazon Elastic Compute Cloud (EC2) instances, Elastic Load Balancing load balancers, etc.
created using AWS CloudFormation the same as if you had created them manually.
You only pay for what you use, with no minimum fees and no required upfront commitments.

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AWS CloudFormation

Benefits

CloudFormation Concepts

Templates

Example Template format

Stacks

Change sets

Example

How does cloudformation works

Template Anatomy

Format Version

JSON

YAML

Description

JSON

YAML

Metadata

JSON

YAML

Meta keys

Parameters

Example

JSON

YAML

Rules

Rule specific intrinsic functions

Mappings

JSON

YAML

Conditions

JSON

YAML

Transform

Resources

JSON

YAML

Output

JSON

YAML

AWS Cloudformation Designer

Benefits

Desginer Overview

How to create Cloudformation

step 1: Login into AWS management console and serach cloudformation service

Click create stack and give all details select template type.

Choose our JSON or YAML file otherwise also create template using designer

Give source details is S3 url or Local file and click next.

Step 2: In this step we can give stack name and check all our configuration and click next

Step 3: Specify stack details

This step attach a IAM role and leave other options by default.

Step 4: Review our configuration and click create.

+ All of our resources are created as a stack we can change and delete using the stack.

Pricing