Infrastructure as Code using AWS

Infrastructure as Code using AWS:- This is a process that describes and provisions all the infrastructure resources in a cloud environment using a simple text file. It is used to model and provision all the resources needed for your applications across all regions and accounts.

Background information on IaaC

A fundamental principle of DevOps is to treat infrastructure the same way developers treat code. Application code has a defined format and syntax. If the code is not written according to the rules of the programming language, applications cannot be created. Code is stored in a version management or source control system that logs a history of code development, changes, and bug fixes. When code is compiled or built into applications, we expect a consistent application to be created, and the build is repeatable and reliable.

Practicing infrastructure as code means applying the same rigor of application code development to infrastructure provisioning. All configurations should be defined in a declarative way and stored in a source control system such as AWS CodeCommit, the same as application code. Infrastructure provisioning, orchestration, and deployment should also support the use of the infrastructure as code.

Infrastructure was traditionally provisioned using a combination of scripts and manual processes. Sometimes these scripts were stored in version control systems or documented step by step in text files or run-books. Often the person writing the run books is not the same person executing these scripts or following through the run-books. If these scripts or runbooks are not updated frequently, they can potentially become a show-stopper in deployments. This results in the creation of new environments not always being repeatable, reliable, or consistent.

In contrast to the preceding, AWS provides a DevOps-focused way of creating and maintaining infrastructure. Similar to the way software developers write application code, AWS provides services that enable the creation, deployment and maintenance of infrastructure in a programmatic, descriptive, and declarative way. These services provide rigor, clarity, and reliability. The AWS services discussed in this paper are core to a DevOps methodology and form the underpinnings of numerous higher-level AWS DevOps principles and practices.

AWS offers following services to define Infrastructure as a code.

i. AWS CloudFormation

AWS CloudFormation is a service that enables developers create AWS resources in an orderly and predictable fashion. Resources are written in text files using JavaScript Object Notation (JSON) or Yet Another Markup Language (YAML) format. The templates require a specific syntax and structure that depends on the types of resources being created and managed. You author your resources in JSON or YAML with any code editor such as AWS Cloud9, check it into a version control system, and then CloudFormation builds the specified services in safe, repeatable manner.

A CloudFormation template is deployed into the AWS environment as a stack. You can manage stacks through the AWS Management Console, AWS Command Line Interface, or AWS CloudFormation APIs. 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 enable you to see how your changes might impact your running resources, especially for critical resources, before implementing them.

ii. AWS Cloud Development Kit (CDK)

The AWS Cloud Development Kit (CDK) is an open source software development framework to model and provision your cloud application resources using familiar programming languages. AWS CDK enables you to model application infrastructure using TypeScript, Python, Java, and .NET. Developers can leverage their existing Integrated Development Environment (IDE), leveraging tools like autocomplete and in-line documentation to accelerate development of infrastructure.

AWS CDK utilizes AWS CloudFormation in the background to provision resources in a safe, repeatable manner. Constructs are the basic building blocks of CDK code. A construct represents a cloud component and encapsulates everything AWS CloudFormation needs to create the component. The AWS CDK includes the AWS Construct Library containing constructs representing many AWS services. By combining constructs together, you can quickly and easily create complex architectures for deployment in AWS.

iii. AWS Cloud Development Kit for Kubernetes

AWS Cloud Development Kit for Kubernetes (cdk8s), is an open-source software development framework for defining Kubernetes applications using general-purpose programming languages.

Once you have defined your application in a programming language (As of date of publication only Python and TypeScript are supported) cdk8s will convert your application description in to pre-Kubernetes YML. This YML file can then be consumed by any Kubernetes cluster running anywhere. Because the structure is defined in a programming language you can use the rich features provided by the programming language. You can use the abstraction feature of the programming language to create your own boiler-plate code and re-use it across all of the deployments.

Implementing infrastructure as code

The benefit of cloud and infrastructure as code is the ability to build and tear down entire environments programmatically and automatically. If architected with resiliency in mind, a recovery environment can be implemented in minutes using AWS CloudFormation templates or AWS Systems Manager automation. Automation is critical for maintaining high availability and fast recovery.

AWS offers a wide breadth of automation tools to accomplish resiliency objectives. AWS Systems Manager helps automate complete runbooks that are used during the recovery of an application during a disaster. You can sequence a complete set of operations to automatically execute on the detection of an event. With Systems Manager automation documents, you can manage these runbooks similar to the way you manage code. You can version them and update them along with every release. This helps keep your recovery plan in sync with released code and updates to infrastructure.