AWS Certified DevOps Engineer Professional (DOP-C02) Review Material – CDK

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Overview

  • AWS Cloud Development Kit (AWS CDK) – an open-source software development framework for defining cloud infrastructure in code and provisioning it through AWS CloudFormation
  • Consists of two(2) parts:
    1. CDK Construct Library
      • A collection of pre-written modular and reusable pieces of code, called constructs, that you can use, modify, and integrate to develop your infrastructure quickly. 
    2. CDK CLI
      • A command-line tool for interacting with CDK apps
  • Supports the following programming languages:
    • TypeScript,
    • JavaScript
    • Python
    • Java
    • C#/.Net
    • Go
  • Difference between Cfn and CDK
    • Cfn defines infrastructure declaratively
    • CDK defines infrastructure imperatively

Core Concepts

  • Projects:
    • Represents the files and folders that contain your CDK code.
    • Vary based on your programming language.
    • Universal Files and Folders:
      • .git
      • .gitignore
      • README.md
      • cdk.json – Configuration file for the AWS CDK. This file provides instructions to the AWS CDK CLI regarding how to run your app.
  • Apps:
    • A collection of one or more CDK stacks.
    • You create an app by defining an app instance in the application file of your project.
    • Stack ‘constructs’ are defined within the scope of an App construct.
    • Stacks within a single app can easily refer to each other’s resources and properties.
    • The overall grouping of your stacks and constructs is known as your CDK App
  • Stacks:
    • The smallest single unit of deployment
    • It represents a collection of AWS resources that you define using CDK constructs.
    • When you deploy CDK apps, the resources within a CDK stack are deployed together as an AWS CloudFormation stack.
    • You define a stack by extending or inheriting from the Stack construct.
    • Stack constructs are defined within the scope of an App construct
    • Stacks are deployed as an AWS CloudFormation stack
    • When you run the 'cdk synth' command for an app with multiple stacks, the cloud assembly includes a separate template for each stack instance.
  • Stages:
    • Represents a group of one or more CDK stacks that are configured to deploy together.
    •  Use stages to deploy the same grouping of stacks to multiple environments, such as development, testing, and production.
  • Constructs:
    • The basic building blocks of AWS Cloud Development Kit (AWS CDK) applications.
    • A construct is a component within your application that represents one or more AWS CloudFormation resources and their configuration.
    • Constructs are classes that you import into your CDK applications from the AWS Construct Library
    • Construct Levels:
      • Level 1 (L1):
        • Also known as CFN resources.
        • The lowest-level construct offers no abstraction.
        • Each L1 construct maps directly to a single AWS CloudFormation resource. 
      • Level 2 (L2):
        • Also known as curated constructs.
        • Developed by the CDK team and are usually the most widely used construct type.
        • Maps directly to single AWS CloudFormation resources but with higher abstraction.
      • Level 3 (L3):
        • Also known as patterns.
        • The highest level of abstraction.
        • Contains a collection of resources that are configured to work together to accomplish a specific task or service within your application.
        • Used to create entire AWS architectures for particular use cases in your application.
  • Context Values:
    • Key-value pairs that can be associated with an app, stack, or construct.
    • Supplied to your app either from a file (usually either cdk.json or cdk.context.json in your project directory) or on the command line.
    • Visible to child constructs, but not to parents or siblings
  • Feature Flags:
  • Aspects:

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