1. Setting up the Docker Compose Application
  2. Layerfile
  3. Setting up the Layerfile
  4. Adding the Layerfile
  5. Video Tutorial
  6. Project Source Code

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Setting up the Docker Compose Application

(You can skip this section if you already have an application using Docker Compose running.) For this example we’re going to build an application that uses Express JS as our server (backend) with a React JS client (frontend). Our application will use Docker Compose to serve both the client and the server. To build your React frontend and Express backend, ensure you have node, npm, npx, Docker, and Docker Compose installed. You can verify with the following commands:
  • node --version
  • npm --version
  • npx --version
  • docker
  • docker-compose
If installed correctly these will give you an output in the terminal. After installed, create a new folder to store your project with mkdir [app_name], and go to that directory with cd [app_name]. First, let’s set up the Express backend. Create a new folder called server with mkdir server, and go to that directory with cd server. In the server folder, run the following commands:
  • npm init
  • npm install express
Once installed, create a new file in the folder called app.js and add the following code:
app.js
const express = require("express");
const app = express();
const port = 5001;
const cors = require("cors");

const corsOptions = {
  origin: function (origin, callback) {
    if ((!origin, callback)) {
      callback(null, true);
    } else {
      callback(new Error("not allowed bycors"));
    }
  },
  credentials: true,
};

app.use(cors(corsOptions));
app.get("/api/", (req, res) => {
  res.send("Hello World!");
});
app.post("/api/get-data", (req, res) => {
  res.send({ text: "webapp.io" });
});
app.listen(port, () => {
  console.log(`App listening on port ${port}`);
});
Next create a file called Dockerfile in the server folder with the following code:
Dockerfile
FROM node:18-buster
RUN apk add --no-cache python2 g++ make
WORKDIR /app
COPY . .
RUN npm install --production
CMD ["node", "app.js"];
EXPOSE 5001
Once those files are added, go back to the root folder with cd ... In the root folder, run the following command npx create-react-app client. This will create your React app. Once the installation has finished, cd into the directory with cd client.NewTabIcon Once in the client, create a file called Dockerfile with the following contents:
Dockerfile
FROM node:18-buster
RUN apk add --no-cache python2 g++ make WORKDIR
/app ENV PATH /app/node_modules/.bin:$PATH COPY package.json ./ COPY package-lock.json
./ RUN npm install COPY . . CMD ["npm", "start"]
EXPOSE 3000
Next, change the content of client/src/App.js to the following:
/client/src/App.js
import { useEffect, useState } from "react";

const App = () => {
  const [data, setData] = useState("");

  useEffect(() => {
    fetch("/api/get-data", { method: "POST" }).then(async (res) => {
      const data = await res.json();
      if (data?.text) {
        setData(data.text);
      } else {
        setData("No Data Received.");
      }
    });
  });
  return <div>Data Received: {data}</div>;
};

export default App;
In this JS file we’re using fetch to request data from our Express backend. Lastly, change the content of client/package.json by adding the following line "proxy": "http://localhost:5001",.
client/package.json
{
  "name": "client",
  "version": "0.1.0",
  "proxy": "http://localhost:5001",
  "private": true,
  ...
}
Once these changes are made, go back to your root folder with cd ... Once in the root folder, create a docker-compose.yml file with the following content:
docker-compose.yml
version: "3.9"
services:
  server:
    build: ./server
    ports:
      - "5001:5001"
    volumes:
      - ./server:/app
  client:
    build: ./client
    ports:
      - "3000:3000"
    volumes:
      - ./client:/app
    depends_on:
      - server
After you’ve made the above changes, run the command docker-compose up to start your application.

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Summary of Steps:

  1. node --version
  2. npm --version
  3. npx --version
  4. docker
  5. docker-compose
  6. mkdir [app_name]
  7. cd [app_name]
  8. mkdir server
  9. cd server
  10. Create /server/app.js file and add content above.
  11. Create /server/Dockerfile file and add content above.
  12. cd . .
  13. npx create-react-app client
  14. cd client
  15. Create /client/Dockerfile file and add the content above.
  16. Change contents of the /client/src/App.js file to the content above.
  17. Change contents of the /client/src/package.json file to the content above.
  18. cd ..
  19. Create a /docker-compose.yml file and add the content above.
  20. docker-compose up

​
Layerfile

Listed below is an example Layerfile for webapp.io which you can use to setup the Docker Compose application. We’ll breakdown this Layerfile in the section below for a set of detailed explanation on what each one of the instructions do.
Layerfile
FROM vm/ubuntu:18.04

MEMORY 2G

# 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

# Install docker compose
RUN curl -L https://github.com/docker/compose/releases/download/1.29.2/docker-compose-`uname -s`-`uname -m` -o /usr/local/bin/docker-compose
RUN chmod +x /usr/local/bin/docker-compose

# Install React
RUN curl -sL https://deb.nodesource.com/setup_14.x | sudo -E bash -
RUN sudo apt-get install -y nodejs
RUN sudo npm install npm@latest -g

ENV NODE_OPTIONS=--max-old-space-size=8192

# Verify docker compose is installed
RUN docker-compose --version

COPY . .

# Install dependencies
WORKDIR client
RUN npm install

WORKDIR /root/server
RUN npm install

RUN docker-compose up -d
EXPOSE WEBSITE http://localhost:5001 /api
EXPOSE WEBSITE http://localhost:3000 /

​
Setting up the Layerfile

If you haven’t already, please sign up to webapp.io, and install webapp.io onto your repository. First let’s breakdown each instruction in our Layerfile.

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1: Set the Image

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FROM vm/ubuntu:18.04

The 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.

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2: Set the Memory

​
MEMORY 2G

The instruction allows you to specify how much memory your environment uses. In this case we use MEMORY 2G to ensure that at least 2GB of memory are available.

​
3. Install Docker

# 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 instruction 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 React application. In this case we’re using the RUN instruction to download Docker.

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4. Install Docker Compose

RUN curl -L https://github.com/docker/compose/releases/download/1.29.2/docker-compose-'uname -s'-'uname -m' -o /usr/local/bin/docker-compose RUN chmod +x /usr/local/bin/docker-compose Similar to the RUN commands above, this will execute the given script, which will install docker compose on the virtual machine so we can run docker-compose up.

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5. Install React

RUN curl -sL https://deb.nodesource.com/setup_14.x | sudo -E bash - RUN sudo apt-get install -y nodejs RUN sudo npm install npm@latest -g Similar to the RUN commands above, this will execute the given scripts to install Node JS and npm which are both needed for React.

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6. Set Node Space Size

ENV NODE_OPTIONS=--max-old-space-size=8192 The instruction persistently sets environment variables in the Layerfile. In this case, the NODE_OPTIONS gets set to a specific size so that it can be consumed later in the React start process.

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7. Verify Docker Compose is installed

RUN docker-compose --version This RUN instruction step is not needed, however we’re adding it here to check if the virtual machine installed Docker Compose successfully.

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8. Get Repository Files

COPY . . The COPY instruction 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.

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9. Install Client Dependencies

WORKDIR client RUN npm install The RUN instruction instruction changes the location from which files are resolved in the runner.

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10. Install Server Dependencies

WORKDIR /root/server RUN npm install Similar to the instruction above, these steps navigate to the Server folder and add all the dependencies needed.

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11. Run Application with Docker Compose

RUN docker-compose up -d After installing all dependencies we run docker-compose up -d to start our React and Server applications.

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12. Expose Server Endpoint on the Virtual Machine

EXPOSE WEBSITE http://localhost:5001 /api The EXPOSE WEBSITE instruction creates a link to view the virtual machine at a specific port. We use EXPOSE WEBSITE to expose the virtual machine on port 3000 which is where the React application runs after running npm start. We use EXPOSE WEBSITE here so we can get a link to our React app to share with stakeholders involved in our projects. This line is especially important since all requests to the /api endpoint will hit our server running on port:5001.

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13. Expose Client Endpoint on the Virtual Machine

EXPOSE WEBSITE http://localhost:3000 / Similar to the instruction above EXPOSE CLIENT exposes the preview environment at port 3000. After expose, you can head to the preview environment link to see it in action. This line is especially important since all requests to the /api endpoint will hit our server running on port:5001.

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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 React application. If you haven’t already, install webapp.io onto your repository containing your full-stack app. Once done, simply create a commit and push your React app to the repository with the new Layerfile. Webapp.io will pick up on the Layerfile and build your application according to the steps in your Layerfile.

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Video Tutorial

Check out our Docker Compose video tutorial for a step-by-step breakdown on how to set up webapp.io with preview environments for a Docker Compose application.