What is the primary purpose of the LABEL instruction in a Dockerfile?

What is the primary purpose of the LABEL instruction in a Dockerfile?

• A. To specify the entrypoint
• B. To provide metadata about the container image
• C. To set the working directory
• D. To install software

Answer: (B)

LABEL is used to attach metadata to the image as key-value pairs. This metadata travels with the image and describes aspects like version, description, license, repository URL, and who maintains it. It doesn’t change how the container runs or what software is installed; it’s purely descriptive data that tooling and registries can read to organize and manage images. You can view these labels with commands like docker inspect, and they can be set in the Dockerfile using LABEL, either as a single instruction with multiple pairs or as multiple LABEL instructions. For example, you might add maintainer, version, and description labels to help users understand what the image is and who produced it. This makes LABEL the go-to way to store metadata about the image, separate from instructions that affect runtime behavior (such as ENTRYPOINT or WORKDIR) or installation (RUN).

LABEL is used to attach metadata to the image as key-value pairs. This metadata travels with the image and describes aspects like version, description, license, repository URL, and who maintains it. It doesn’t change how the container runs or what software is installed; it’s purely descriptive data that tooling and registries can read to organize and manage images. You can view these labels with commands like docker inspect, and they can be set in the Dockerfile using LABEL, either as a single instruction with multiple pairs or as multiple LABEL instructions. For example, you might add maintainer, version, and description labels to help users understand what the image is and who produced it. This makes LABEL the go-to way to store metadata about the image, separate from instructions that affect runtime behavior (such as ENTRYPOINT or WORKDIR) or installation (RUN).