BuildKit for improved builds in Docker - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the command to enable BuildKit for Docker builds.

Docker

DOCKER_BUILDKIT=[1] docker build .

Drag options to blanks, or click blank then click option'

Atrue

B0

Cenable

D1

Attempts:

3 left

💡 Hint

Common Mistakes

Using 0 disables BuildKit, so the build won't use it.

Using 'true' or 'enable' are not valid values for this environment variable.

Setting DOCKER_BUILDKIT=1 enables BuildKit for faster and more efficient Docker builds.

2fill in blank

medium

Complete the Dockerfile command to use BuildKit's cache mount feature.

Docker

RUN --mount=type=[1],target=/root/.cache pip install -r requirements.txt

Drag options to blanks, or click blank then click option'

Atmpfs

Bbind

Ccache

Dvolume

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'bind' mounts host directories, not cache.

Using 'tmpfs' creates temporary memory mounts, not persistent cache.

The cache mount type allows BuildKit to cache files between builds, speeding up repeated installs.

3fill in blank

hard

Fix the error in the command to build with BuildKit and output a progress bar.

Docker

DOCKER_BUILDKIT=1 docker build --progress=[1] .

Drag options to blanks, or click blank then click option'

Adetailed

Bauto

Cbar

Dplain

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'bar' is not a valid progress option.

Using 'detailed' is not recognized by Docker.

The --progress=auto option lets Docker choose the best progress output, including a progress bar in terminals.

4fill in blank

hard

Fill both blanks to create a Dockerfile snippet that uses BuildKit cache and sets a build argument.

Docker

ARG CACHEBUST=[1]
RUN --mount=type=[2],target=/root/.cache pip install -r requirements.txt

Drag options to blanks, or click blank then click option'

A1

Bcache

C0

Dbind

Attempts:

3 left

💡 Hint

Common Mistakes

Using '0' disables cache busting.

Using 'bind' instead of 'cache' causes no caching.

Setting ARG CACHEBUST=1 allows cache busting, and --mount=type=cache enables caching pip files.

5fill in blank

hard

Fill all three blanks to create a BuildKit-enabled Docker build command with a custom target and output directory.

Docker

DOCKER_BUILDKIT=1 docker build --target [1] --output type=[2],dest=[3] .

Drag options to blanks, or click blank then click option'

Aproduction

Blocal

C./output

Dcache

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'cache' as output type is invalid here.

Missing the destination path causes errors.

Use --target production to build a specific stage, --output type=local to output files locally, and dest=./output to set the output folder.

Practice

1. What is the main purpose of enabling BuildKit in Docker builds?

easy

A. To speed up builds and provide smarter build features

B. To disable caching during Docker builds

C. To automatically push images to Docker Hub

D. To run containers in debug mode

Solution

1. Step 1: Understand BuildKit's role

   BuildKit is designed to improve Docker build speed and add smarter features like better caching and parallel steps.

2. Step 2: Compare options

   Options A, C, and D describe unrelated Docker features. Only To speed up builds and provide smarter build features correctly describes BuildKit's purpose.

3. Final Answer:

   To speed up builds and provide smarter build features -> Option A

4. Quick Check:

   BuildKit purpose = speed and smart builds [OK]

Hint: BuildKit improves build speed and features, not disables or pushes [OK]

Common Mistakes:

• Thinking BuildKit disables cache
• Confusing BuildKit with image pushing
• Assuming BuildKit runs containers

2. Which command correctly enables BuildKit for a Docker build?

easy

A. docker build --enable-buildkit .

B. docker build --buildkit=enable .

C. docker build -buildkit 1 .

D. DOCKER_BUILDKIT=1 docker build .

Solution

1. Step 1: Recall how to enable BuildKit

   BuildKit is enabled by setting the environment variable DOCKER_BUILDKIT=1 before running the docker build command.

2. Step 2: Analyze options

   Only DOCKER_BUILDKIT=1 docker build . uses the correct environment variable syntax. Options B, C, and D use invalid flags or syntax.

3. Final Answer:

   DOCKER_BUILDKIT=1 docker build . -> Option D

4. Quick Check:

   Enable BuildKit with env var DOCKER_BUILDKIT=1 [OK]

Hint: Set DOCKER_BUILDKIT=1 before docker build command [OK]

Common Mistakes:

• Using invalid flags like --buildkit=enable
• Trying to pass BuildKit as a docker build option
• Forgetting to set environment variable

3. What output difference will you see when running DOCKER_BUILDKIT=1 docker build . compared to a normal build?

medium

A. More detailed and clearer build step output

B. No output is shown during the build

C. Build output is shown in JSON format only

D. Build output is slower and less informative

Solution

1. Step 1: Understand BuildKit output changes

   BuildKit provides clearer, more detailed output with progress bars and parallel step info.

2. Step 2: Compare output options

   More detailed and clearer build step output matches this behavior. Options B and D are incorrect because output is shown and faster. Build output is shown in JSON format only is wrong because JSON output is not default.

3. Final Answer:

   More detailed and clearer build step output -> Option A

4. Quick Check:

   BuildKit output = clearer and detailed [OK]

Hint: BuildKit shows clearer, detailed build progress output [OK]

Common Mistakes:

• Expecting no output during build
• Thinking output is JSON by default
• Assuming BuildKit slows down output

4. You tried to enable BuildKit with docker build --buildkit=1 . but it failed. What is the likely cause?

medium

A. BuildKit is not supported on your Docker version

B. The flag --buildkit=1 is invalid; BuildKit must be enabled via environment variable

C. You need to add --enable-buildkit flag instead

D. You must run docker build as root to enable BuildKit

Solution

1. Step 1: Check how BuildKit is enabled

   BuildKit is enabled by setting the environment variable DOCKER_BUILDKIT=1, not by a docker build flag.

2. Step 2: Analyze the error cause

   Using --buildkit=1 is invalid syntax, causing the failure. Options B, C, and D are incorrect because BuildKit is supported in recent Docker versions, no such flag exists, and root is not required.

3. Final Answer:

   The flag --buildkit=1 is invalid; BuildKit must be enabled via environment variable -> Option B

4. Quick Check:

   BuildKit enabled only by env var, not flags [OK]

Hint: BuildKit enabled only by DOCKER_BUILDKIT=1 env var [OK]

Common Mistakes:

• Trying to enable BuildKit with invalid flags
• Assuming root permission is needed
• Believing BuildKit is disabled on all Docker versions

5. You want to speed up your Docker build by using BuildKit and also use a cache from a previous build stored locally. Which command correctly achieves this?

hard

A. docker build --cache-from=type=local,src=/path/to/cache .

B. docker build --buildkit=1 --cache-from=local:/path/to/cache .

C. DOCKER_BUILDKIT=1 docker build --cache-from=type=local,src=/path/to/cache .

D. DOCKER_BUILDKIT=1 docker build --cache-from=local:/path/to/cache .

Solution

1. Step 1: Enable BuildKit correctly

   BuildKit must be enabled by setting DOCKER_BUILDKIT=1 environment variable before the docker build command.

2. Step 2: Use correct cache-from syntax

   BuildKit supports advanced cache-from syntax like --cache-from=type=local,src=path. DOCKER_BUILDKIT=1 docker build --cache-from=type=local,src=/path/to/cache . uses this correctly. Options B and C use invalid flags or syntax. docker build --cache-from=type=local,src=/path/to/cache . misses enabling BuildKit.

3. Final Answer:

   DOCKER_BUILDKIT=1 docker build --cache-from=type=local,src=/path/to/cache . -> Option C

4. Quick Check:

   Enable BuildKit + correct cache-from syntax = DOCKER_BUILDKIT=1 docker build --cache-from=type=local,src=/path/to/cache . [OK]

Hint: Set DOCKER_BUILDKIT=1 and use --cache-from=type=local,src=path [OK]

Common Mistakes:

• Using --buildkit=1 flag instead of env var
• Incorrect cache-from syntax
• Forgetting to enable BuildKit