--- title: Containerize a Node.js application linkTitle: Containerize your app weight: 10 keywords: node.js, node, containerize, initialize description: Learn how to containerize a Node.js application. aliases: - /get-started/nodejs/build-images/ - /language/nodejs/build-images/ - /language/nodejs/run-containers/ - /language/nodejs/containerize/ - /guides/language/nodejs/containerize/ --- ## Prerequisites - You have installed the latest version of [Docker Desktop](/get-started/get-docker.md). - You have a [git client](https://git-scm.com/downloads). The examples in this section use a command-line based git client, but you can use any client. ## Overview This section walks you through containerizing and running a Node.js application. ## Get the sample application Clone the sample application to use with this guide. Open a terminal, change directory to a directory that you want to work in, and run the following command to clone the repository: ```console $ git clone https://github.com/docker/docker-nodejs-sample && cd docker-nodejs-sample ``` ## Initialize Docker assets Now that you have an application, you can create the necessary Docker assets to containerize your application. You can use Docker Desktop's built-in Docker Init feature to help streamline the process, or you can manually create the assets. {{< tabs >}} {{< tab name="Use Docker Init" >}} Inside the `docker-nodejs-sample` directory, run the `docker init` command in a terminal. `docker init` provides some default configuration, but you'll need to answer a few questions about your application. Refer to the following example to answer the prompts from `docker init` and use the same answers for your prompts. ```console $ docker init Welcome to the Docker Init CLI! This utility will walk you through creating the following files with sensible defaults for your project: - .dockerignore - Dockerfile - compose.yaml - README.Docker.md Let's get started! ? What application platform does your project use? Node ? What version of Node do you want to use? 18.0.0 ? Which package manager do you want to use? npm ? What command do you want to use to start the app: node src/index.js ? What port does your server listen on? 3000 ``` {{< /tab >}} {{< tab name="Manually create assets" >}} If you don't have Docker Desktop installed or prefer creating the assets manually, you can create the following files in your project directory. Create a file named `Dockerfile` with the following contents. ```dockerfile {collapse=true,title=Dockerfile} # syntax=docker/dockerfile:1 # Comments are provided throughout this file to help you get started. # If you need more help, visit the Dockerfile reference guide at # https://docs.docker.com/go/dockerfile-reference/ # Want to help us make this template better? Share your feedback here: https://forms.gle/ybq9Krt8jtBL3iCk7 ARG NODE_VERSION=18.0.0 FROM node:${NODE_VERSION}-alpine # Use production node environment by default. ENV NODE_ENV production WORKDIR /usr/src/app # Download dependencies as a separate step to take advantage of Docker's caching. # Leverage a cache mount to /root/.npm to speed up subsequent builds. # Leverage a bind mounts to package.json and package-lock.json to avoid having to copy them into # into this layer. RUN --mount=type=bind,source=package.json,target=package.json \ --mount=type=bind,source=package-lock.json,target=package-lock.json \ --mount=type=cache,target=/root/.npm \ npm ci --omit=dev # Run the application as a non-root user. USER node # Copy the rest of the source files into the image. COPY . . # Expose the port that the application listens on. EXPOSE 3000 # Run the application. CMD node src/index.js ``` Create a file named `compose.yaml` with the following contents. ```yaml {collapse=true,title=compose.yaml} # Comments are provided throughout this file to help you get started. # If you need more help, visit the Docker Compose reference guide at # https://docs.docker.com/go/compose-spec-reference/ # Here the instructions define your application as a service called "server". # This service is built from the Dockerfile in the current directory. # You can add other services your application may depend on here, such as a # database or a cache. For examples, see the Awesome Compose repository: # https://github.com/docker/awesome-compose services: server: build: context: . environment: NODE_ENV: production ports: - 3000:3000 # The commented out section below is an example of how to define a PostgreSQL # database that your application can use. `depends_on` tells Docker Compose to # start the database before your application. The `db-data` volume persists the # database data between container restarts. The `db-password` secret is used # to set the database password. You must create `db/password.txt` and add # a password of your choosing to it before running `docker compose up`. # depends_on: # db: # condition: service_healthy # db: # image: postgres # restart: always # user: postgres # secrets: # - db-password # volumes: # - db-data:/var/lib/postgresql/data # environment: # - POSTGRES_DB=example # - POSTGRES_PASSWORD_FILE=/run/secrets/db-password # expose: # - 5432 # healthcheck: # test: [ "CMD", "pg_isready" ] # interval: 10s # timeout: 5s # retries: 5 # volumes: # db-data: # secrets: # db-password: # file: db/password.txt ``` Create a file named `.dockerignore` with the following contents. ```text {collapse=true,title=".dockerignore"} # Include any files or directories that you don't want to be copied to your # container here (e.g., local build artifacts, temporary files, etc.). # # For more help, visit the .dockerignore file reference guide at # https://docs.docker.com/go/build-context-dockerignore/ **/.classpath **/.dockerignore **/.env **/.git **/.gitignore **/.project **/.settings **/.toolstarget **/.vs **/.vscode **/.next **/.cache **/*.*proj.user **/*.dbmdl **/*.jfm **/charts **/docker-compose* **/compose.y*ml **/Dockerfile* **/node_modules **/npm-debug.log **/obj **/secrets.dev.yaml **/values.dev.yaml **/build **/dist LICENSE README.md ``` {{< /tab >}} {{< /tabs >}} You should now have at least the following contents in your `docker-nodejs-sample` directory. ```text ├── docker-nodejs-sample/ │ ├── spec/ │ ├── src/ │ ├── .dockerignore │ ├── .gitignore │ ├── compose.yaml │ ├── Dockerfile │ ├── package-lock.json │ ├── package.json │ └── README.md ``` To learn more about the files, see the following: - [Dockerfile](/reference/dockerfile.md) - [.dockerignore](/reference/dockerfile.md#dockerignore-file) - [compose.yaml](/reference/compose-file/_index.md) ## Run the application Inside the `docker-nodejs-sample` directory, run the following command in a terminal. ```console $ docker compose up --build ``` Open a browser and view the application at [http://localhost:3000](http://localhost:3000). You should see a simple todo application. In the terminal, press `ctrl`+`c` to stop the application. ### Run the application in the background You can run the application detached from the terminal by adding the `-d` option. Inside the `docker-nodejs-sample` directory, run the following command in a terminal. ```console $ docker compose up --build -d ``` Open a browser and view the application at [http://localhost:3000](http://localhost:3000). You should see a simple todo application. In the terminal, run the following command to stop the application. ```console $ docker compose down ``` For more information about Compose commands, see the [Compose CLI reference](/reference/cli/docker/compose/_index.md). ## Summary In this section, you learned how you can containerize and run your Node.js application using Docker. Related information: - [Dockerfile reference](/reference/dockerfile.md) - [.dockerignore file reference](/reference/dockerfile.md#dockerignore-file) - [Docker Compose overview](/manuals/compose/_index.md) ## Next steps In the next section, you'll learn how you can develop your application using containers.