Image naming conventions (registry/image:tag) in Docker - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the general format of a Docker image name?

A Docker image name usually follows this format: <registry>/<image>:<tag>. The registry is optional and defaults to Docker Hub if omitted.

beginner

What does the <tag> part in a Docker image name represent?

The <tag> specifies the version or variant of the image. If no tag is given, Docker uses the default tag 'latest'.

intermediate

Why include a registry in the Docker image name?

Including a registry tells Docker where to find the image. It can be Docker Hub or a private registry. This helps Docker pull the image from the correct source.

beginner

Example: What does 'myregistry.com/myapp/backend:1.2' mean?

It means the image is stored in 'myregistry.com' under the repository 'myapp/backend' with the version tag '1.2'.

beginner

What happens if you omit the tag in a Docker image name?

Docker assumes the tag 'latest' by default, so 'ubuntu' is the same as 'ubuntu:latest'.

What is the default tag used if none is specified in a Docker image name?

A 1.0

B stable

C default

D latest

If no tag is specified, Docker uses 'latest' as the default tag.

Which part of the Docker image name specifies where to find the image?

A tag

B registry

C image

D version

The registry part tells Docker which server or service to pull the image from.

In the image name 'nginx:alpine', what does 'alpine' represent?

A Tag

B Image name

C Registry

D Repository

'alpine' is the tag specifying a lightweight version of the nginx image.

What happens if you use 'docker pull ubuntu' without a tag?

A Pulls ubuntu:default

B Pulls ubuntu:stable

C Pulls ubuntu:latest

D Returns an error

Docker assumes the 'latest' tag if none is provided.

Which of these is a valid Docker image name?

A myregistry.com/myapp:1.0

B myapp:1.0:extra

C registry//image:tag

D image:tag:version

The format /: is valid. Multiple colons or double slashes are invalid.

Explain the parts of a Docker image name and why each part is important.

Think about where the image is stored, what it is called, and which version to use.

Describe what happens when you pull a Docker image without specifying a tag.

Consider what Docker assumes and why specifying a tag can be safer.