# Backend API Issue: Special Characters in MongoDB URI

Every DevOps journey has its hiccups—here’s one I ran into while deploying my backend API.

### The Problem

My FastAPI backend needed to connect to MongoDB using a URI like this:

```javascript
mongodb+srv://username:password@cluster.mongodb.net/mydb?retryWrites=true&w=majority
```

But this URI has **special characters** like `&`, which caused **issues during deployment** via CircleCI. When injecting the URI into the `systemd` service file using `awk` or `sed`, the special characters were getting misinterpreted—so the backend failed to connect.

### What Was Happening

Originally, I tried writing the MongoDB URI directly into the service file during deployment. This looked something like:

```javascript
ExecStart=/usr/bin/env MONGODB_URI=mongodb+srv://...&w=majority uvicorn main:app
```

But shell tools like `awk` and `sed` didn’t play nice with the `&`, breaking or corrupting the string.

### The Fix

**Environment File to the Rescue.**  
Instead of embedding the URI directly, I created a separate file for environment variables:

#### Step 1: Create an environment file

```javascript
# /opt/resume-api/api.env
MONGODB_URI="mongodb+srv://...&w=majority"
```

#### Step 2: Reference it in the systemd service file

```javascript
EnvironmentFile=/opt/resume-api/api.env
ExecStart=/usr/bin/env uvicorn main:app --host 0.0.0.0 --port 8000
```

This way, `systemd` loads the environment variables safely from the file.

### 💡 Why This Works

* It **avoids shell parsing issues**—no more fighting with escaping special characters.
    
* It’s cleaner and more secure—you can `.gitignore` the file and even manage it via secrets.
    

### Result

The backend now connects to MongoDB without a hitch, and deployments via CircleCI run smoothly every time.