3 Containers and Containerization Free Online FlashCards

What is a container?

A container is an application process running in an isolated environment on a host operating system.

What is a container image?

A container image is a read-only packaged template containing the files and configuration needed to start an application.

How does a container differ from an image?

An image is the packaged template; a container is a running or stopped instance created from that template.

What is one benefit of building images in layers?

Image layers can be reused when building or downloading related images.

Where do changes made by a running container go?

Changes made while a container runs go into a separate writable layer; the image itself remains unchanged.

Why doesn't an image tag guarantee the same image every time?

A tag is a human-readable image label, but it can be reassigned and therefore may not always select the same image.

What does an image digest identify?

A digest identifies particular image content more precisely than a tag.

What is a container registry used for?

A container registry stores and distributes images. Repositories in a registry contain images identified by tags or digests.

How can you reduce risk when using container images?

Use trusted publishers, verify image identity where appropriate, and keep images updated; a familiar image name alone does not prove trustworthiness.

What does a container runtime do?

A container runtime configures the isolated environment and resource controls, then starts and manages the application process.

In `docker run --name web -p 8080:80 nginx:latest`, what does `-p 8080:80` do?

The command maps host port 8080 to container port 80, allowing traffic on the host port to reach the container port.

How do containers and VMs differ in their use of kernels?

Containers generally share the host kernel; a VM runs a guest operating system with its own kernel.