Building a Type-Safe Go Backend for a React Web App
Tags: go, tutorial, react, webdev
Published: 2023-12-10 11:11:06

**In this short guide we'll create and deploy a Go backend for a web app with a React frontend.** We'll be using [Encore](https://encore.dev) to build a production-ready Go backend, that can be deployed to the cloud without manually setting up infrastructure.

**🚀 What's on deck:**
- Install Encore
- Create your app from a template
- Run locally and try your frontend
- Deploy to Encore's free development cloud

## 💽 Install Encore

If this is the first time you're using Encore, you first need to install the CLI that runs the local environment. Use the appropriate command for your system:
- **macOS:** `brew install encoredev/tap/encore`
- **Linux:** `curl -L https://encore.dev/install.sh | bash`
- **Windows:** `iwr https://encore.dev/install.ps1 | iex`

## 🔨 Create app

When you have [installed Encore](https://encore.dev/docs/install), create a new Encore application and clone this example:

```bash
encore app create my-backend --example=react-starter
```

## 🏁 Running locally

Run your Encore backend from your app root directory using:
```bash
encore run
```

In a different terminal window, run the Next.js frontend:
```bash
cd frontend
npm install
npm run dev
```

👉 Open [http://localhost:5173](http://localhost:5173) in your browser to see the result.

![React frontend](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/u61nnxnyf22p7glr2i9v.jpg)


### 🧪 Encore's Local Development Dashboard

While `encore run` is running, open <http://localhost:9400/> to view Encore's local developer dashboard. Here you can make API requests using the API explorer and see [traces](https://encore.dev/docs/observability/tracing) for any requests you make.

![Encore local dev dashboard](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/1brerbowy62l8f2fag0q.png)

## 🤝 Generate a request client and stay type-safe

Keep the contract between the backend and frontend in sync by regenerating the request client whenever you make a change to an Encore endpoint. This helps ensure end-to-end type-safety.✨

```bash
npm run gen # Deployed Encore staging environment
# or
npm run gen:local # Locally running Encore backend
```

## 🚀 Deploy to the cloud

Deploy your app to a staging environment in Encore's free development cloud:

```bash
git add -A .
git commit -m 'Initial commit'
git push encore
```

👉 Then head over to the [Cloud Dashboard](https://app.encore.dev) to monitor your deployment and find your production URL.

From there you can also see metrics, traces, connect your app to a GitHub repo to get automatic deploys on new commits, and connect your own AWS or GCP account to use for deployment.

![Encore Cloud Dashboard](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/7kmyqylyk7lxvuvosl4k.png)

### CORS configuration

If you are running into CORS issues when calling your Encore API from your frontend, then you may need to specify which origins are allowed to access your API (via browsers).

You do this by specifying the `global_cors` key in the `encore.app` file, which has the following structure:

```jsonc
global_cors: {
  // allow_origins_without_credentials specifies the allowed origins for requests
  // that don't include credentials. If nil it defaults to allowing all domains
  // (equivalent to ["*"]).
  "allow_origins_without_credentials": [
    "<ORIGIN-GOES-HERE>"
  ],
        
  // allow_origins_with_credentials specifies the allowed origins for requests
  // that include credentials. If a request is made from an Origin in this list
  // Encore responds with Access-Control-Allow-Origin: <Origin>.
  //
  // The URLs in this list may include wildcards (e.g. "https://*.example.com"
  // or "https://*-myapp.example.com").
  "allow_origins_with_credentials": [
    "<DOMAIN-GOES-HERE>"
  ]
}
```

More information on CORS configuration can be found in the [Encore docs](https://encore.dev/docs/develop/cors).

## 🔥 Great job - you're done!

You now have the foundations of a scalable and production-ready web app foundation running in the cloud. 🎉

For real production-scale traffic, you can [connect your cloud account](https://encore.dev/docs/deploy/own-cloud) (AWS/GCP) and deploy there with a click.

Keep building with these Open Source Encore [App Templates](https://encore.dev/templates).👈

If you have questions or want to share your work, join the developers' hangout in [Encore's community Slack](https://encore.dev/slack).👈

## 📚 Learn More
- [Encore Documentation](https://encore.dev/docs)
- [React API Reference](https://react.dev/reference/react)