Deployment & Containerization

The Mood application is designed to be deployed as a set of Docker containers. This approach ensures a consistent and reproducible environment from development to production. This page details the containerization strategy.

docker-compose.yml

The docker-compose.yml file orchestrates the two main services:

• postgres: A standard postgres:16-alpine image that runs the database. It uses a named volume (postgres_data) for data persistence.
• web: The main application service, built from the local Dockerfile.

A key feature is the healthcheck on the postgres service and the depends_on condition in the web service. This ensures the web container will only start after the database is fully initialized and ready to accept connections, preventing startup errors.

Dockerfile

The Dockerfile uses a multi-stage build to create a lean and optimized final image for production.

1. deps Stage: Installs all dependencies (dependencies and devDependencies) using bun install. This layer is cached by Docker, speeding up subsequent builds if dependencies haven't changed.
2. builder Stage: Copies the source code and node_modules from the previous stage, then runs bun run build. This compiles the Next.js application into an optimized production output in the .next directory.
3. runner Stage: This is the final, lightweight image. It installs only production dependencies (bun install --production), copies the build artifacts from the builder stage, and sets up the entrypoint.sh script.

entrypoint.sh

This script is the ENTRYPOINT for the final runner container. It performs critical runtime tasks before starting the application server:

1. Wait for Database: It enters a loop that uses pg_isready to pause execution until the postgres container is fully ready.
2. Apply Migrations: It runs npx prisma migrate deploy. This command applies any pending database migrations. It's safe to run on every startup and ensures the database schema is always in sync with the Prisma schema.
3. Start Application: Finally, it executes exec bun run start to start the Next.js production server.

This automated migration step makes deployments and updates seamless.