AWS CloudFormation Templates

• Variables can be selected individually to avoid having to manually hard code them.
• All resources will need to be declared, whether they are an S3 bucket or an EC2 instance.  Each resource will have multiple properties tied to it, each of which can have subproperties related to it.
• The template must also declare any output variables that need to be imported into other stacks.
• Not all variables need to be chosen to deploy.  Variables can be declared as needed.
• To avoid issues with regional-dependent variables, mapping will set conditions for selected variables that need to be in specific AWS Regions.
• To make establishing variables easier, AWS does have a complete library of variables and other references to help make compiling templates easier.
• Users can update the properties for resources in existing stacks. These changes can range from simple configuration changes, such as updating the alarm threshold on a CloudWatch alarm, to more complex changes, such as updating the Amazon Machine Image (AMI) running on an Amazon EC2 instance. Many of the AWS resources in a template can be updated, and we continue to add support for more.
• Conditions help establish certain circumstances under which new AWS resources are procured. For example, users might want to differentiate using a template when deploying to a production or test environment.
• Building on the template’s declarative language, the Transform section declares any macros the template will use. These macros will then execute in the specified order, so be mindful of how they are listed.

To further enhance the efficiency of managing multiple stacks, you can export a stack’s output values, allowing other stacks within the same AWS account and region to import these values. This facilitates seamless information sharing between stacks, which is essential for maintaining consistency and efficiency in large-scale deployments. Additionally, the resource import feature can be utilized for resources created outside of the CloudFormation environment. The capability to move resources between stacks by implementing a Retain deletion policy allows for greater flexibility and control over resource lifecycle management. Stack nesting and the creation of specialized stacks, such as those for Microsoft Windows, are also supported, providing structured and scalable options for complex infrastructure setups.

Security will be another concern. With AWS’s shared security responsibility policies, developers are responsible for specifying which inbound or outbound content should be screened. In addition to fully using AWS’s other security tools, how traffic going in or out will be scrutinized will need to be specified with the other variables.
IAM can be utilized with AWS CloudFormation to effectively manage authorization and access control within an AWS environment. By using IAM with CloudFormation, administrators can specify and enforce what actions different users or roles can perform in relation to CloudFormation activities.
With IAM policies, administrators can define which users have the authorization to carry out specific tasks related to CloudFormation—such as viewing stack templates, creating new stacks, or deleting existing stacks. Moreover, administrators can further refine access by specifying what AWS services and resources are accessible to each user. This level of control ensures that users can only interact with resources that have been explicitly granted to them, thus enhancing security and compliance measures within the AWS environment.

• Under no circumstances should users have sensitive data in any of the variable categories, such as names.  Worse, embedding credentials into the templates by default.  If necessary, use a dynamic reference instead.
• By its default, CloudFormation will encrypt data at rest, while it’s in transit, and while it is within the environment network.  However, customers are still responsible for setting encryption and storage policies.
• There are options to validate templates before using them to ensure dependencies and syntax errors don’t occur before the template is used to create any AWS resources.

Templates are incredibly useful for setting up new AWS resources and environments with less effort on the developer’s part.  Setting up resources involves extensive variable configuration and setup before it can properly launch.  Better yet, templates can be repeatedly reused or shared within an organization with sufficient leeway in how those templates are utilized.