> ## Documentation Index > Fetch the complete documentation index at: https://docs.webapp.io/llms.txt > Use this file to discover all available pages before exploring further. # Docker 1. [Setting up the Docker Application](./docker#setting-up-the-docker-application). 2. [Layerfile](./docker#layerfile) 3. [Setting up the Layerfile](./docker#setting-up-the-layerfile) 4. [Adding the Layerfile](./docker#adding-the-layerfile) 5. [Video Tutorial](./docker#video-tutorial) 6. [Project Source Code](https://github.com/joshuadsouza/webappio-docs-examples/tree/master/webappio-docker-example) ## Setting up the Docker Application **(You can skip this section if you already have an app with Docker running.)** For this example we'll build an Express JS application that runs through Docker. To build your Express application through Docker, ensure you have node, npm, and Docker installed on your computer. You can verify if node, npm, and Docker are installed by running the following commands in your terminal: * `node --version` * `npm --version` * `docker` If installed correctly these commands will all give you an output in the terminal. If `node` and `npm` are installed, create a new directory with `mkdir [app_name]` - replacing `[app_name]` with the name of your application. Next navigate into the directory with `cd [app_name]` and run the following commands: 1. `npm init` 2. `npm install express` After installing express, create a new file called `app.js` at the root of the folder and use the following to set up an endpoint for your application: ```javascript app.js theme={null} const express = require("express"); const app = express(); const port = 3000; app.get("/", (req, res) => { res.send("Hello World"); }); app.get("/test", (req, res) => { res.send("Test Route!"); }); app.listen(port, () => { console.log(`Example app listening on port ${port}`); }); ``` After creating your `app.js` file, create another file called `Dockerfile` in the root of your folder, and add the following contents: ```docker Dockerfile theme={null} FROM node:12-alpine RUN apk add --no-cache python2 g++ make WORKDIR /app COPY . . RUN npm install --production CMD ["node", "app.js"] EXPOSE 80 ``` Once your dockerfile is created, you can use the following commands to run your Docker app: 1. `docker build -t image .` 2. `docker run -d -p 80:80 image` ### Summary of Steps: 1. `node --version` 2. `npm --version` 3. `mkdir [app_name]` 4. `cd [app_name]` 5. Create your `app.js` file with the content above 6. Create your `Dockerfile` file with the content above 7. `docker build -t image .` 8. `docker run -d -p 80:80 image` ## Layerfile Listed below is an example Layerfile for webapp.io which you can use to setup a basic Express application deployed with Docker. We'll breakdown this Layerfile in the section below for a set of detailed explanation on what each one of the instructions do. ```docker Layerfile theme={null} FROM vm/ubuntu:18.04 # install the latest version of Docker, as in the official Docker installation tutorial. RUN apt-get update && \ apt-get install ca-certificates curl gnupg lsb-release && \ sudo mkdir -p /etc/apt/keyrings && \ curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /etc/apt/keyrings/docker.gpg && \ echo \ "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.gpg] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable" |\ sudo tee /etc/apt/sources.list.d/docker.list > /dev/null && \ apt-get update && \ apt-get install docker-ce docker-ce-cli containerd.io COPY . . RUN docker build -t image . RUN docker run -d -p 80:80 image EXPOSE WEBSITE http://localhost:80 ``` ## Setting up the Layerfile If you haven't already, please sign up to [webapp.io](/sign-up), and install webapp.io onto your repository. Let's breakdown each instruction in our Layerfile. ### 1: Set the Image `FROM vm/ubuntu:18.04` The `FROM` instruction tells webapp.io what base to use to run tests from. There can only be one `FROM` line, and in this case we're using the `ubuntu:18.04` virtual machine image. If you're familiar with AWS Ec2 Instances, this is similar to creating a virtual machine from the ubuntu 18.04 image. ### 2. Install Docker ```Layerfile theme={null} # install the latest version of Docker, as in the official Docker installation tutorial. RUN apt-get update && \ apt-get install ca-certificates curl gnupg lsb-release && \ sudo mkdir -p /etc/apt/keyrings && \ curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /etc/apt/keyrings/docker.gpg && \ echo \ "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.gpg] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable" |\ sudo tee /etc/apt/sources.list.d/docker.list > /dev/null && \ apt-get update && \ apt-get install docker-ce docker-ce-cli containerd.io ``` The `RUN` [instruction](../layerfile-reference/run) will run the given script, and fails the Layerfile if the script fails. In this case, we're using the `RUN` command to install the dependencies we need to build and run the Express application in Docker. In this case we're using the `RUN` instruction to download Docker. ### 3. Get Repository Files `COPY . .` The `COPY` [instruction](../layerfile-reference/copy) moves files from your repository to the virtual machine. The Layerfile will pick up on the files in the repository that you are making the commit for, and will copy those files into the virtual machine so you can run you project. ### 4. Build the Docker image `RUN docker build -t image .` Similar to the `RUN` commands above, this will execute the given script `docker build -t image .`, which will install build the Docker image for the Express app. ### 5. Run the Docker image `RUN docker run -d -p 80:80 image` Similar to the `RUN` commands above, this will execute the given script `docker run -d -p 80:80 image`, which will run the Docker image that was previously built. ### 6. Expose Docker Port on the Virtual Machine `EXPOSE WEBSITE http://localhost:80` The `EXPOSE WEBSITE` [instruction](../layerfile-reference/expose-website) creates a link to view the virtual machine at a specific port. We use `EXPOSE WEBSITE` to expose the virtual machine on port 80 which is where the Express application runs after running `ng serve`. We use `EXPOSE WEBSITE` here so we can get a link to our Express app to share with stakeholders involved in our projects. ## Adding the Layerfile The last step in this process is to add the Layerfile to your repository. Simply create a file called `Layerfile` (no file extension) in the root of your Express application. If you haven't already, install webapp.io onto your repository containing your Express app. Once done, simply create a commit and push your Express app to the repository with the new Layerfile. Webapp.io will pick up on the Layerfile and build your Express application according to the steps in your Layerfile. ## Video Tutorial Check out our Docker video tutorial before for a step-by-step breakdown on how to set up webapp.io with preview environments for an Express application: