Why image optimization matters in Docker - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the Dockerfile line to set the base image to Alpine Linux, which is small and efficient.

Docker

FROM [1]

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

Aalpine:latest

Bubuntu:latest

Cdebian:latest

Dcentos:latest

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing a larger base image like ubuntu increases image size unnecessarily.

Using alpine:latest as the base image helps keep the Docker image small and optimized.

2fill in blank

medium

Complete the Dockerfile command to remove package cache after installing packages to reduce image size.

Docker

RUN apk add --no-cache curl && [1]

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Aapt-get clean

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

Crm -rf /var/cache/apk/*

Dyum clean all

Attempts:

3 left

💡 Hint

Common Mistakes

Using commands for other package managers like apt or yum.

In Alpine Linux, /var/cache/apk/ holds package cache. Removing it reduces image size.

3fill in blank

hard

Fix the error in the Dockerfile line to copy only necessary files to keep the image small.

Docker

COPY [1] /app/

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A.

Bsrc/

Cnode_modules/

Dbuild/

Attempts:

3 left

💡 Hint

Common Mistakes

Copying the entire current directory (.) adds unnecessary files.

Copying the build/ directory ensures only the compiled app files are included, avoiding unnecessary files like source code or dependencies.

4fill in blank

hard

Fill both blanks to create a multi-stage Dockerfile that builds and then copies only the final app.

Docker

FROM node:16-alpine AS builder
RUN npm install && npm run build
FROM alpine:latest
COPY --from=builder [1] [2]

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A/app/build

B/app

C/usr/src/app

D/build

Attempts:

3 left

💡 Hint

Common Mistakes

Copying the entire source directory or wrong paths.

The build output is in /app/build in the builder stage, and it is copied to /app in the final image to keep it small.

5fill in blank

hard

Fill all three blanks to write a Dockerfile snippet that cleans up after installing packages and sets a working directory.

Docker

FROM alpine:latest
RUN apk add --no-cache git [1] && [2]
WORKDIR [3]

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

Abash

Brm -rf /var/cache/apk/*

C/app

Dcurl

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting to clean cache or setting wrong working directory.

Installing bash adds a shell, cleaning cache reduces image size, and setting /app as working directory organizes files.