How to Dockerize SvelteKit

This guide provides a step-by-step process for containerizing a SvelteKit application using Docker, making it easier to deploy and manage. To start, you need to set up a SvelteKit project and install the adapter-node, which helps build the site for Node.js. The adapter-node is crucial for containerization, and you can install it by running the command npm i -D @sveltejs/adapter-node. Once installed, you need to update the svelte.config.js file to use the adapter-node. Next, you need to create a Dockerfile, which tells Docker how to build and run your SvelteKit application. The Dockerfile consists of two stages: the builder stage and the final stage. The builder stage installs dependencies, builds the SvelteKit app, and prunes dependencies to production-only. The final stage copies the built app, production node_modules, and package.json from the builder stage, exposes port 3000, sets the environment to production, and specifies the command to run the app. To keep the Docker build context clean and speed up the build process, you need to create a .dockerignore file in your project root. Using a multi-stage build helps keep the final image small by discarding unnecessary files and tools after the build process. You can build your Docker image by running the command docker build -t my-sveltekit-app, and then run your containerized app with docker run -p 3000:3000 my-sveltekit-app. Handling environment variables in Docker is important, and SvelteKit provides four ways to import environment variables. When deploying your app, you need to refer to the platform's documentation for handling build-time and runtime environment variables. Additionally, you need to set the ORIGIN environment variable correctly to avoid cross-site POST form submission errors. Finally, the guide provides some production tips, including adding a /health endpoint to your app, setting Node.js memory limits, and regularly scanning your container for vulnerabilities. By following these steps, you can create a dockerized SvelteKit application that is optimized for production.