deploymentintermediate

Docker

A tool that packages your app and everything it needs into a container — so it works identically on any computer.

💡 In plain English: Docker is like a lunchbox — everything your app needs is packed inside, so it works the same wherever you open it.

Quick answer

Docker packages applications into containers — lightweight, portable units that include the app code and all its dependencies. For vibe coders, Docker is usually invisible: Railway uses Nixpacks to automatically create containers from your code.

What is Docker?

The classic developer problem: your app works on your laptop but crashes on the server. Docker solves this by packaging your app with everything it needs into a container that runs identically everywhere.

A container is like a lightweight virtual machine — it has your app, Node.js, all npm packages, and configuration, packaged together.

Most vibe coders never write a Dockerfile. Railway detects your framework and creates the container automatically. You need Docker directly when deploying to a raw VPS (DigitalOcean Droplet) or running databases locally for development.

In Vibe Coding

Railway builds Docker containers for you automatically using Nixpacks. The one Docker command most vibe coders actually use: running a local Postgres database for development.

Example

For example: Your app works on your Mac but crashes on the production server running Linux. With Docker, you package your app into a container that runs identically on both — same OS, same dependencies, same result.

Run local Postgres with Docker

# Run Postgres locally (for development)
docker run -d \
  --name my-postgres \
  -e POSTGRES_PASSWORD=mypassword \
  -e POSTGRES_DB=myapp \
  -p 5432:5432 \
  postgres:16

# Connection string:
# postgresql://postgres:mypassword@localhost:5432/myapp

Related Terms

Deploy

Making your app live on the internet for real.

Railway

Simple hosting for apps that need a backend or database.

Backend

The hidden part of your app that handles data and logic.

Related Guides

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Frequently Asked Questions

No. Railway builds containers automatically. Only need Docker for raw VPS deployments or local databases.

A way to run multiple containers together — your app + database + Redis, all starting with one command.