Lesson 3 of 6

Dockerfile Basics

Describe how to build an application image.

A Dockerfile contains ordered instructions used to build an image.

Common instructions include FROM, WORKDIR, COPY, RUN, EXPOSE and CMD.

Example

FROM node:22-alpine
WORKDIR /app
COPY . .
RUN npm ci
CMD ["npm", "start"]

Practice challenge

Identify which line chooses the base image.