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Dockerfile & Build

Building custom images with Dockerfiles

Step 1 of 3

A Dockerfile is a text file with instructions to build an image. Each instruction creates a layer. Layers are cached for faster builds.

bash

FROM node:20-alpine
WORKDIR /app
COPY package*.json ./
RUN npm install
COPY . .
EXPOSE 3000
CMD ["node", "index.js"]

Application codetop layer

Dependencies

Config files

OS packages

Base OS layerbase layer