Language and Framework Guides
Run an Express Container App

11min
Back4App Containers is a powerful platform for hosting Express Applications. With its ability to automatically deploy Dockerized applications, you can launch your project in a scalable and flexible environment with ease. 
In this guide, we will walk you through the process of preparing and deploying your Express application on Back4App Containers, covering everything from simple projects to more complex setups. We will begin with the necessary preparations, then move on to dockerizing the application, testing it locally, pushing the project to GitHub, setting up the project on Back4App Containers, monitoring deployment, and troubleshooting common issues.
If you have any questions or comments, feel free to join the conversation in the #Containers channel on the Back4app Community on Slack. Anytime you can also contact us at [email protected].
At anytime if you want to check a sample working NodeJS Express project on Back4app containers go to : ﻿https://github.com/templates-back4app/containers-node-express-sample﻿﻿
1. Prepare your Express application
To prepare your Express application for deployment on Back4App Containers, follow these steps:
Ensure that you have Node.js and npm installed on your local machine. You can check this by running node -v and npm -v in your terminal. If you don't have them installed, download and install the latest LTS version of Node.js from the official website.
If you haven't already, create a new Express application using the Express application generator or any other preferred method. Make sure to keep your application code clean and well-organized.
Create a .gitignore file in your project's root directory to exclude unnecessary files and folders from your Git repository. This file should include, at a minimum, the following entries:
Text
node_modules/
.DS_Store
.env
node_modules/
.DS_Store
.env
﻿
Add a package.json file to your project's root directory if it doesn't already exist. This file should include information about your application, such as its name, version, description, and dependencies.
Ensure that your application listens on the correct port. When running in a container, your application should listen on the port specified by the PORT environment variable. Update your app.listen() statement accordingly:
Text
const port = process.env.PORT || 3000;
app.listen(port, () => {
  console.log(`Listening on port ${port}`);
});
const port = process.env.PORT || 3000;
app.listen(port, () => {
  console.log(`Listening on port ${port}`);
});
﻿
2. Dockerization
To dockerize your Express application, create a Dockerfile in your project's root directory with the following contents:
Dockerfile
FROM node:14

WORKDIR /usr/src/app

COPY package*.json ./

RUN npm install

COPY . .

EXPOSE 3000

CMD [ "node", "app.js" ]
FROM node:14

WORKDIR /usr/src/app

COPY package*.json ./

RUN npm install

COPY . .

EXPOSE 3000

CMD [ "node", "app.js" ]
﻿
This Dockerfile sets up a Docker container with Node.js, installs your application's dependencies, and runs your application on port 3000.
3. Test your Project Locally
Before pushing your project to GitHub, test it locally by running the following commands:
Text
docker build -t your-image-name .
docker run -p 3000:3000 your-image-name
docker build -t your-image-name .
docker run -p 3000:3000 your-image-name
﻿
Visit http://localhost:3000 in your web browser to ensure your application is running correctly.
4. Push your project to GitHub
To push your project to a GitHub repository, follow these steps:
Create a new GitHub repository, if you haven't already.
Initialize a new Git repository in your project's root directory by running git init.
Add your project files to the Git repository by running git add ..
Commit your changes with a descriptive message using git commit -m "Your commit message".
Add the GitHub repository as a remote using git remote add origin https://github.com/yourusername/your-repo-name.git.
Push your changes to the GitHub repository using git push -u origin main.
5. Deploy your application on Back4App Containers
To deploy your Express application on Back4App Containers, follow these steps:
Log in to your Back4App account and navigate to the "Containers" section.
Click "Create New App" and then choose "Edit GitHub Permissions".
Authorize Back4App to access your GitHub account and select the repository containing your Express project.
Once connected to your repo select it to coninue.
Choose the appropriate branch and configure any required environment variables.
Click "Create" to start the deployment process. Back4App Containers will automatically build and deploy your application using the provided Dockerfile.
You can follow these Docs for a better guidance:
﻿1- Connect you GitHub repo with Back4app﻿
﻿2- Prepare your project for deployment﻿
In summary, containers will follow the instructions detailed on your Dockerfile and start to create your App.
After configuring your container app, Back4app will automatically build the container image using your Dockerfile and deploy your Express app on the platform. The deployment process may take a few minutes, depending on the size and complexity of your application.
Once the deployment is complete, Back4app Containers will provide you with a unique URL where you can access your deployed app.
6. Monitor deployment and address possible errors
After deploying your application on Back4App Containers, monitor its progress in the "Deployment" tab on your Container App Dashboard. Pay attention to any error or warning messages and address them accordingly. Check the "Logs" tab for more detailed information about the deployment process and runtime logs.
7. Troubleshooting common problems
Here are some common problems you may encounter when deploying and running an Express application on Back4App Containers, along with their solutions:
Problem: The application does not start, and the logs indicate an issue with the port configuration.
Solution: Make sure your application listens on the port specified by the PORT environment variable, as shown in the "Prepare your Express application" section.
Problem: The application fails to connect to a database or other external service.
Solution: Verify that the necessary environment variables, such as connection strings, are correctly set in the deployment settings on Back4App Containers. Ensure that the external services are accessible from the container environment.
Problem: The Docker build fails due to missing dependencies or incompatible Node.js versions.
Solution: Check your Dockerfile and ensure that it correctly installs all required dependencies and uses the correct Node.js version.
Problem: The application runs correctly locally but fails when deployed on Back4App Containers.
Solution: Make sure that all necessary files, such as configuration files and assets, are included in your Git repository and the Docker container.
Problem: The application starts, but the logs indicate performance issues or resource constraints.
Solution: Review your application's resource usage and consider optimizing your code or increasing the resources allocated to your container on Back4App Containers.
When troubleshooting, remember that logs are your best friend. The Back4App Containers platform provides detailed logs for your application, allowing you to identify and resolve issues quickly. By addressing these common problems, you can ensure a smooth deployment and runtime experience for your Express application on Back4App Containers.
With the help of this guide, you should now have a better understanding of how to prepare, deploy, and troubleshoot a Express application on Back4App Containers. This powerful platform offers a seamless and efficient way to host your Rust applications, freeing you from the complexities of DevOps and allowing you to focus on your code.
At anytime if you want to check a sample working NodeJS Express project on Back4app containers go to : ﻿https://github.com/templates-back4app/containers-node-express-sample﻿﻿
﻿
Updated 16 May 2023
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