> ## Documentation Index
> Fetch the complete documentation index at: https://docs.dcdeploy.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Deploy Express.js on DCDeploy

> Guide for deploying Express.js applications on DCDeploy

This guide walks you through deploying an Express.js application on DCDeploy, including setup, build configuration, and best practices.

***

## Quick Start: Hello World

You can try deploying a minimal Express.js app to test the workflow.

1. Create a new project:
   ```bash theme={null}
   mkdir hello-dcdeploy
   cd hello-dcdeploy
   npm init -y
   npm install express
   ```
2. Create an index.js file with the following code:

```js theme={null}
const express = require("express");
const app = express();

const PORT = process.env.PORT || 3000;

app.get("/", (req, res) => {
  res.send("Hello DCDeploy 🚀 from Express.js!");
});

app.listen(PORT, "0.0.0.0", () => {
  console.log(`Server running on http://0.0.0.0:${PORT}`);
});
```

3. Update package.json scripts:

```json theme={null}
{
  "scripts": {
    "start": "node index.js"
  }
}
```

4. Run locally:

```bash theme={null}
npm start
```

5. Commit and push to GitHub/Git provider.
6. Deploy on DCDeploy using the steps in the guide below.

## Overview

Express.js is a lightweight Node.js web framework often used for REST APIs and backend services.
On DCDeploy, you can deploy Express.js apps using:

* Build from Code (auto-detected Node.js project) – easiest method.
* Custom Dockerfile – for advanced control over runtime and dependencies.

## Prerequisites

* Express.js project (index.js or app.js entrypoint).
* package.json with a valid start script.
* GitHub (or Git) repository to push your project.
* (Optional) Dockerfile if you want a custom build.

## Step-by-Step Guide

1. Prepare Your Express App

* Ensure package.json has a start script that runs your server.
* App must listen on 0.0.0.0 and use the PORT environment variable.

2. Add Dockerfile (optional)

```dockerfile theme={null}
FROM node:18-alpine
WORKDIR /app
COPY package*.json ./
RUN npm install --production
COPY . .
EXPOSE 3000
CMD ["npm", "start"]
```

3. Push Code to Git

* Initialize Git, commit files, and push to your Git provider.
* Add .dockerignore if using Docker.

4. Deploy on DCDeploy

* In DCDeploy dashboard → Deploy tab of your environment.
* Create a new service → select Build from Code or Docker Registry.
* Provide repo + branch.
* Set port to 3000 (or the one used in your app).
* Configure environment variables for secrets, DB URLs, etc.
* Choose machine type (CPU, RAM) based on traffic needs.
* Deploy and monitor logs.

## Example Service Config

```yaml theme={null}
services:
  express-app:
    build:
      context: ./
      dockerfilePath: ./Dockerfile
      repo: your-username/express-app
      ref: main
      refType: branch
      autoBuild: true
    ports:
      - 3000
    protocol: https
    minScale: 1
    maxScale: 2
    environment:
      NODE_ENV: production
      API_KEY: your-secret-key
```

## Best Practices

* Use environment variables (not hardcoded secrets).
* Use internal networking in DCDeploy to connect databases/APIs securely.
* Add health check endpoints (e.g. /healthz).
* Log errors clearly for debugging.
* Scale services with minScale/maxScale depending on workload.

## Troubleshooting

| Problem                  | Likely Cause                                 | Solution                                      |
| ------------------------ | -------------------------------------------- | --------------------------------------------- |
| App crashes on deploy    | Wrong entrypoint or missing dependencies     | Check `start` script, install deps.           |
| Not accessible           | App not listening on `0.0.0.0` or wrong port | Ensure `listen("0.0.0.0", process.env.PORT)`. |
| Build timeout / too slow | Large deps or missing Docker ignore          | Optimize deps, use `.dockerignore`.           |
| Env vars not working     | Missing DCDeploy config                      | Add env vars in dashboard.                    |