Building images with docker build - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of the docker build command?

The docker build command creates a Docker image from a set of instructions in a Dockerfile. It packages your application and its environment into a reusable image.

beginner

What file does docker build use by default to build an image?

By default, docker build looks for a file named Dockerfile in the specified build context directory.

beginner

What does the -t option do in the docker build command?

The -t option tags the image with a name and optionally a version, making it easier to identify and run later.

intermediate

Explain the term 'build context' in Docker image building.

The build context is the set of files and folders sent to the Docker daemon during the build. It includes the Dockerfile and any files referenced inside it.

intermediate

Why is it important to keep the build context small?

A smaller build context speeds up the build process because fewer files are sent to the Docker daemon. It also reduces the chance of accidentally including sensitive or unnecessary files.

What is the default filename that docker build looks for?

A Dockerfile

B docker-compose.yml

C buildfile

D imagefile

The default file for docker build is Dockerfile.

Which option tags the image with a name during build?

A -t

B -b

C -i

D -n

The -t option tags the image with a name and optional version.

What does the build context include?

A Only the Dockerfile

B Only files listed in .dockerignore

C Only files copied during the build

D All files in the current directory and subdirectories

The build context includes all files in the directory sent to Docker unless excluded by .dockerignore.

Why should you keep the build context small?

A To reduce image size

B To speed up the build process

C To increase container startup time

D To avoid using Dockerfile

A smaller build context speeds up the build by sending fewer files to Docker.

Which command builds a Docker image from the current directory and tags it as 'myapp:latest'?

A docker create -t myapp:latest .

B docker run -t myapp:latest .

C docker build -t myapp:latest .

D docker build -n myapp:latest .

docker build -t myapp:latest . builds and tags the image from the current directory.

Describe the process of building a Docker image using docker build. Include what files are involved and how tagging works.

Think about the Dockerfile, the folder you build from, and how you name the image.

Explain why managing the build context is important when building Docker images.

Consider what happens when you send too many files to Docker during build.