Infrastructure as Code (IaC) has emerged as a transformative approach, revolutionizing how cloud resources are provisioned, deployed, and managed. IaC refers to the practice of defining and managing IT infrastructure using machine-readable files such as code scripts and templates. IaC brings the principles of software development to infrastructure management, treating infrastructure configurations as code that can be version-controlled, tested, and automated.
AWS CloudFormation is a powerful IaC service provided by Amazon Web Services (AWS) that enables users to manage and provision their cloud infrastructure in a scalable and efficient manner. It allows developers and system administrators to define and deploy cloud resources using templates, automating the entire process of creating and managing AWS resources. The subsequent sections below explore the core concepts of AWS CloudFormation.
Contents
Understanding AWS CloudFormation Concepts
Source: AWS
Template
At the core of AWS CloudFormation is the Template, which defines infrastructure and resources in a declarative format. Templates are written in either JSON (JavaScript Object Notation) or YAML (YAML Ain’t Markup Language) and follow a well-defined structure.
CloudFormation templates are human-readable, version-controlled, and can be shared across teams. They provide a clear and consistent way to define a desired AWS infrastructure, ensuring that the environment can be reproduced reliably whenever needed.
Stack
A stack in AWS CloudFormation is a collection of AWS resources that are created, updated, and deleted together as a single unit. All the resources in a stack are defined in a CloudFormation template. The template outlines the configuration of the resources needed for a specific application or workload.
Creating a stack is a straightforward process. Users provide a CloudFormation template and AWS CloudFormation takes care of provisioning and configuring the specified resources. Similarly, updating or deleting a stack ensures that all resources within that stack are modified or removed accordingly.
Resources
Resources such as Amazon EC2 instances, Amazon S3 buckets, or AWS Lambda functions, are the building blocks of AWS infrastructure. In a CloudFormation template, each resource is declared with its type, properties, and any dependencies it might have on other resources within the same stack. AWS CloudFormation takes care of provisioning and configuring these resources based on the defined template, ensuring that the desired state of the infrastructure is achieved.
Parameters
Parameters allow for the customization of CloudFormation templates at runtime. They act as inputs to the template and enable dynamic configuration of resources. For example, parameters such as instance type, desired storage size, or the number of instances during stack creation can be specified to make a template versatile and reusable across different environments.
Using parameters promotes a modular approach to infrastructure management and enables the deployment of similar stacks with slight variations depending on the input parameters.
Outputs
Outputs in CloudFormation help extract information from the stack once it is created or updated successfully. Outputs serve as a means to access specific values or attributes of resources defined in the CloudFormation template, enabling the sharing of information between resources.
Building CloudFormation Templates
Writing CloudFormation Templates
CloudFormation templates follow a simple structure, comprising a mix of JSON or YAML syntax along with intrinsic functions to allow dynamic configurations. A typical template begins with defining the format version and metadata, followed by the resources, parameters, and outputs sections.
Intrinsic functions such as “Fn::Join,” “Fn::Ref,” and “Fn::Sub,” can be used to create dynamic values or manipulate the template as required.
Incorporating AWS-specific Resource Configurations
Each resource in a CloudFormation template comes with its specific properties and attributes, which determine its configuration and behavior. For example, an EC2 instance resource has properties such as instance type, security groups, and AMI ID, while an S3 bucket resource may have properties such as bucket name, access control policies, and versioning settings.
These resource properties can be set to default values or defined using parameters, allowing for flexible and custom configurations.
Managing Dependencies between Resources
In a CloudFormation template, resources may have dependencies on each other. For example, a load balancer must be created before the instances it balances. CloudFormation automatically manages these dependencies to ensure the correct order of resource creation.
However, when dealing with complex infrastructures, it is important to be mindful of circular dependencies or resources that are dependent on other stacks to avoid deployment issues.
Deploying Stacks with AWS CloudFormation
Creating and Updating Stacks
Creating a stack in AWS CloudFormation is a straightforward process. Once a template is provided, AWS CloudFormation takes care of provisioning and configuring the specified resources accordingly.
Stack updates can be performed to modify the infrastructure such as adding and removing resources, or updating their properties. CloudFormation makes the changes in a controlled manner, ensuring minimal disruption to the existing infrastructure. To facilitate smooth stack updates, the usage of Change sets is recommended. Change sets assist in previewing and understanding how proposed changes to a stack might affect running resources.
Stack Policies
AWS CloudFormation stack policies are JSON-based documents that define and control update operations that can be made to a stack’s resources. Defining a stack policy helps prevent specific resources from being modified or deleted, protecting critical components from unintentional changes. Stack policies offer an added layer of security and control over stack updates, particularly in production environments.
Rollbacks and Monitoring
During stack creation or updates, AWS CloudFormation continuously monitors the process and automatically rolls back changes if any of the resources fail to be created or updated successfully. The rollback mechanism helps ensure that a stack remains in a consistent state and prevents partial deployments.
AWS CloudFormation also provides comprehensive monitoring and logging capabilities, allowing users to track stack events and identify any potential issues during the deployment process.
Advanced CloudFormation Features
Nested Stacks
A nested stack is a CloudFormation stack that is defined as a resource within another stack. Using nested stacks helps break down complex infrastructures into smaller, manageable components, making it easier to maintain, update, and reuse as templates.
CloudFormation StackSets
StackSets enable the deployment of stacks across multiple accounts and regions simultaneously. They are particularly useful for organizations with a multi-account structure or for scenarios where the same infrastructure needs to be deployed in different regions.
Custom Resources
In some cases, the built-in resource types may not fulfill specific requirements. Custom resources help extend CloudFormation by enabling the writing of custom provisioning logic in templates. Custom resources can perform any desired action outside the standard AWS resource types, providing greater flexibility and customization in stack deployments.
Macros
CloudFormation macros are used to preprocess templates before the creation of stacks. Macros enable the inclusion of reusable code snippets, making it easier to maintain and manage templates. They can also help in implementing custom behaviors and patterns across templates.
Integrating CloudFormation with AWS Services
AWS CloudFormation and AWS IAM
AWS Identity and Access Management (IAM) plays a critical role in controlling permissions and security in AWS CloudFormation. Defining IAM roles, users, or groups and assigning granular permissions helps control access to CloudFormation stacks, templates, and resources. IAM conditions can be used to apply fine-grained access controls based on factors such as resource tags, stack names, or parameters.
AWS CloudFormation and AWS CloudTrail
AWS CloudTrail can be integrated with AWS CloudFormation to provide an audit trail of all API calls made to CloudFormation and the changes made to stacks and resources. CloudTrail logs can be used to monitor changes, track modifications, and troubleshoot issues.
Conclusion
AWS CloudFormation is a powerful and efficient solution for managing cloud resources. By abstracting away the complexities of resource provisioning and configuration, CloudFormation empowers organizations to focus on innovation and application development, confident in the knowledge that their infrastructure is secure, consistent, and easily reproducible.
About TrackIt
TrackIt is an Amazon Web Services Advanced Tier Services Partner specializing in cloud management, consulting, and software development solutions based in Marina del Rey, CA.
TrackIt specializes in Modern Software Development, DevOps, Infrastructure-As-Code, Serverless, CI/CD, and Containerization with specialized expertise in Media & Entertainment workflows, High-Performance Computing environments, and data storage.
In addition to providing cloud management, consulting, and modern software development services, TrackIt also provides an open-source AWS cost management tool that allows users to optimize their costs and resources on AWS.