Docker can look intimidating at first.

Images, containers, volumes, networks, registries, Dockerfiles...

The basic idea is actually simple:

Package an application together with the environment it needs to run.

The "Works on My Machine" Problem

Imagine your application requires:

Node.js 22 MongoDB Specific npm dependencies Environment variables

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A teammate might have:

Node.js 20 Different MongoDB version Different operating system

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Problems appear.

Docker helps standardize the environment.

Dockerfile

A basic Node.js Dockerfile might look like:

FROM node:22

WORKDIR /app

COPY package*.json ./

RUN npm install

COPY .…