Images

A Docker image is a lightweight, stand-alone, executable software package that includes everything needed to run a piece of software, including the code, a runtime, libraries, environment variables, and config files.

Images are just data identfiable with hashes. Think of them like bootable disks:

f3d495355b4e

Images contain

• Code - The actual code that runs your application.
• Runtime - The runtime environment where your code executes, for instance, Node.js, Python, or Java runtime.
• Libraries - Any libraries or frameworks your code depends on.
• Environment Variables - Configurable parameters your code uses to interact with its environment.
• Config Files - Configuration files which might contain settings or setup information for your application.
• Dependencies - Other resources or files your application needs to run.

Image Registries

Images may stored locally or hosted on various registries

• Docker Hub - this is the default registry for pulling/pushing
• Google Container Registry (GCR)
• Amazon Elastic Container Registry (ECR)
• Azure Container Registry (ACR)