AWS Classroom Series – 03/Feb/2021

AWS Cloud Formation

• This is a service that helps you model and setup AWS resources so that we spend less time managing the resources and focus on applications that run in AWS.
• We describe our AWS resources in a template in a syntax specified by Cloudformation Grammar and Cloudformation takes care of provisioning and configuring the resources.
• This helps in
  • recreating the infrastructure into various environments.
  • Easily controlling and tracking changes in your infrastructure.
• Terminology
  • Template:
    • This is a JSON or YAML formatted text file which describes the resources which we want to create.
  • Stack:
    • To execute CF template we create a stack and in the stack all the resources created are managed.
  • Changeset:
    • To make changes in the executing resources of stack, we create changesets i.e. summary of proposed changes.
    • We update stacks using changesets.
• How does CF Work
  • Create or use an existing template
  • Save the template locallay or in S3 bucket
  • Now AWS Cloudformation will create stack based on your template

JSON and YAML

• These are the files which can store data in name value pairs.
• Json and YAML Refer Here

AWS Cloudformation Template Grammar

• Refer Here for the template structure
• Json Structure

{
  "AWSTemplateFormatVersion" : "version date",

  "Description" : "JSON 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
  }
}

• In the above template structure the only required field is resources, which describes the resources which you want to create in AWS

{
    "Resources": {
        set of resources
    }
}

• Lets Try to write a cloudformation template to create an s3 bucket
  • ManualSteps:
• Now lets see how to create a resource in Cf template. Refer Here
• Now google for AWS cloudformation resource s3 Refer Here for the resource documentation
• We have created a template which looks like

{
	"Resources": {
		"mys3bucket" : {
			"Type" : "AWS::S3::Bucket",
			"Properties" : {
				"BucketName": "qts3fromcftbd"
			}
		}
	}
}

• Now lets create stack
• Now delete the stack to delete the resources created by cloudformation.
• Refer Here for the changeset.