Container Images
In depthConcept
Also known as: Docker Images
Immutable snapshots of an application and all its dependencies, ready to run as a container.
Container Images, explained
Written by EduVerseWhat it is
A container image is a packaged, read-only template that holds your application together with everything it needs to run: runtime, libraries, system files and the start command. You build it from a Dockerfile, and every container you start from that image begins in exactly the same state.
Why teams use it
“It works on my machine” usually means the environments differ. An image removes most of that difference, because the same image runs on your laptop, in the test environment and in production. Images are built in layers, so a rebuild after a small code change only redoes the layers that changed.
An example from work
You run docker build -t shop-api . and watch Docker work through the steps in your Dockerfile. Because RUN npm install comes after COPY . ., every small code change reinstalls all dependencies. Copying package.json first and installing before copying the rest makes rebuilds much faster.
Our own explanation, not a quote from the book.
In the book
Sentences from The Software Realm, Decoded that mention Container Images, exactly as printed.
1 more passages about Container Images in the full book
Read every conversation where Container Images comes up, with the interactive slides and demos.
Where it fits
The building blocks of containers, stored in registries
Coverage in the book
Covered in depth: multiple pages with explanations, examples and simulations.
