Tagging images during build in Docker - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of tagging a Docker image during build?

Tagging a Docker image during build helps to give the image a meaningful name and version. This makes it easier to identify, manage, and deploy specific versions of the image.

beginner

How do you tag a Docker image during the build process?

You use the docker build command with the -t option followed by the tag name, like docker build -t myapp:1.0 . to tag the image as 'myapp' with version '1.0'.

intermediate

What does the tag latest mean in Docker images?

The latest tag is the default tag if none is specified. It usually points to the most recent or stable version of the image, but it is just a label and does not guarantee the newest image.

intermediate

Can you assign multiple tags to a Docker image during build?

Yes, you can assign multiple tags by using multiple -t options in the docker build command, for example: docker build -t myapp:1.0 -t myapp:stable .

beginner

Why is it important to use version tags instead of only latest?

Using version tags helps avoid confusion and errors by clearly specifying which image version to use. It improves deployment reliability and makes rollbacks easier if needed.

Which command tags a Docker image as 'myapp' with version '2.0' during build?

A docker build -t myapp:2.0 .

B docker tag myapp 2.0

C docker run -t myapp:2.0

D docker push myapp:2.0

The docker build -t myapp:2.0 . command builds the image and tags it as 'myapp' with version '2.0'.

What happens if you do not specify a tag when building a Docker image?

A The image is tagged as 'latest' by default

B The build fails

C The image is not saved

D Docker asks you to enter a tag

If no tag is specified, Docker automatically tags the image as 'latest'.

How can you assign two tags 'v1' and 'stable' to the same image during build?

A docker build -t myapp:v1,stable .

B docker build -t myapp:v1 -t myapp:stable .

C docker tag myapp:v1 stable

D docker build -tag myapp:v1 stable

You use multiple -t options to assign multiple tags during build.

Why should you avoid relying only on the 'latest' tag in production?

A Because 'latest' images cannot be pushed to registries

B Because 'latest' images are always unstable

C Because 'latest' tag is deprecated

D Because 'latest' may point to different images over time causing unpredictability

The 'latest' tag can change and may cause unexpected image versions to be deployed.

Which of these is NOT a valid Docker image tag format?

A myapp:beta-2

B myapp:1.0

C myapp:1.0-

D myapp:v1.0.0

Docker tags must not end with a hyphen or period; '1.0-' ends with a hyphen, making it invalid.

Explain how to tag a Docker image during the build process and why tagging is useful.

Think about how you name files to keep track of versions.

Describe the risks of using only the 'latest' tag for Docker images in production environments.

Consider what happens if you always use the newest file without knowing its exact version.