Image layers concept in Docker - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to build a Docker image from a Dockerfile.

Docker

docker build -t myapp [1] Dockerfile .

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A-d

B-f

C--rm

D--push

Attempts:

3 left

💡 Hint

Common Mistakes

Using -d which is for detached mode in run command

Using --push which is for pushing images

Using --rm which removes intermediate containers

The -f option specifies the Dockerfile to use when building the image.

2fill in blank

medium

Complete the Dockerfile line to add a new file to the image.

Docker

COPY [1] /app/

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Afile.txt

B./app/file.txt

C/app/file.txt

D/file.txt

Attempts:

3 left

💡 Hint

Common Mistakes

Using absolute paths which are not in the build context

Adding destination path in the source position

The COPY command copies a file from the build context (local folder) to the image. The source is just the filename.

3fill in blank

hard

Fix the error in the Dockerfile line that sets the working directory.

Docker

WORKDIR [1]app

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A/

B./

C/home/

Attempts:

3 left

💡 Hint

Common Mistakes

Using relative paths like 'app' or './app'

Missing the leading slash for absolute path

The WORKDIR path should be an absolute path starting with a slash. Using /app sets the working directory to /app.

4fill in blank

hard

Fill both blanks to create a Dockerfile line that runs a command and creates a new image layer.

Docker

RUN [1] && [2]

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Aapt-get update

Bapt-get install -y curl

Cecho 'Hello World'

Drm -rf /var/lib/apt/lists/*

Attempts:

3 left

💡 Hint

Common Mistakes

Running install before update

Using echo which does not install software

The RUN command executes shell commands and creates a new image layer. Updating package lists and installing curl are common steps.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension that maps image layers to their sizes if size is greater than zero.

Docker

layer_sizes = { [1]: [2] for [3], size in layers.items() if size > 0 }

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Alayer

Bsize

Dlayer.upper()

Attempts:

3 left

💡 Hint

Common Mistakes

Using layer instead of layer.upper() for keys

Mixing up keys and values in comprehension

This comprehension creates a dictionary with layer names in uppercase as keys and their sizes as values, filtering out layers with size zero.