Lesson 3 of 6
Dockerfile Basics
Describe how to build an application image.
Introduction
A Dockerfile contains ordered instructions used to build an image.
Common instructions include FROM, WORKDIR, COPY, RUN, EXPOSE and CMD.
Key insight
Describe how to build an application image.
Example
FROM node:22-alpine
WORKDIR /app
COPY . .
RUN npm ci
CMD ["npm", "start"]Read the example line by line, then try changing one value.
Real-world example
Dockerfile Basics helps developers build useful applications.
Practice challenge
Identify which line chooses the base image.