Laboratorio: empezando con CloudFormation

CloudFormation allows us to provision infrastructure as code. To test CloudFormation, using a template we will create a stack from which an S3 bucket will be deployed. Then, we will update the stack by adding another S3 bucket, and finally we will delete it.

Understanding the template

In this repository you will find the CloudFormation template that we will use. The template has the following JSON structure (remember, CloudFormation accepts JSON or YAML format):

{ " AWSTemplateFormatVersion": "2010-09-09", " Description": "this template does XXXX", " Metadata": {}, " Parameters": {}, " Mappings": {}, " Conditions": {}, " Transform": {}, " Resources": {}, " Outputs": {} }

These parameters correspond to the following:

• AWSTemplateFormatVersion: this parameter is optional. Here we specify the template version
• Description: text string describing the template. It must follow AWSTemplateFormatVersion.
• Metadata: objects that provide additional information about the template.
• Parameters: values that we will pass to the template when it is executed, either during the creation or update of the *stack.
• Mappings: allows to assign a set of values to a specific key. For example, to set values based on a region, we can create a mapping that uses the name of a region as a key and contains the values we want to specify for each region.
• Conditions: controls that resources are created or values are assigned to those resources based on a condition. For example, we can assign different values for production or test environments.
• Transform: Specifies the macros that AWS CloudFormation uses to process the template.
• Resources: here we declare the resources to be included in the stack. For example, EC2 instances or S3 buckets.
• Outputs: declares output values that can be used in other stacks.

Steps to create the stack

1. We go to the CloudFormation page from our AWS account (on this page we can learn more about the service in question).
2. Here we click on "Create stack".
3. To create the stack, under "Specify template" we select "Load a template file", and load the createstack.json file. This file simply defines an S3 bucket called "platzilab".

{ " Resources": { " platzilab": { " Type": "AWS::S3::Bucket"} } } }

4. We click next and then choose a name for the stack. In this case, we call it cfnlab, and click next.
5. Optionally, we can add labels to identify the stack, and an IAM role.
6. We leave the rest of the configurations by default and click next. Then it will take us to review the configurations, and we click on "Create stack".
7. We will be able to see the stack creation process, the events and the resources that were created. If you look at the name of the created bucket, you will see that it is composed by the name of the stack, the name we assigned to the bucket in the template, and a random text string. This is to avoid creating duplicate named resources.

Contribution created with contributions from: Ciro Villafraz.