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

# DDAgentForPythonApp

## Datadog Agent Setup for Python App on EC2

**Purpose:**
Install and configure the Datadog Agent to collect host metrics and APM traces from a Python FastAPI application. This setup works for autoscaling environments and ensures host metrics and traces are reported automatically.

***

### 1. Prerequisites

* EC2 instance with Python 3.8+ and a virtual environment (`venv`) installed.
* Datadog account with API key.
* Security group allowing outbound HTTPS (port 443) for agent reporting.
* Python app installed at `/home/<user>/<app-name>` (example uses `example-app`).

***

### 2. Install Datadog Agent

1. Set environment variables for your Datadog API key, site, and environment:

```bash theme={null}
export DD_API_KEY=XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
export DD_SITE="datadoghq.com"   # Use datadoghq.eu for EU, datadoghq.in for India
export DD_ENV=prod
```

2. Install Datadog Agent v7:

```bash theme={null}
bash -c "$(curl -L https://install.datadoghq.com/scripts/install_script_agent7.sh)"
```

3. Verify installation:

```bash theme={null}
sudo systemctl status datadog-agent
sudo datadog-agent status
```

***

### 3. Configure Datadog Agent

1. Edit the main configuration file:

```bash theme={null}
sudo nano /etc/datadog-agent/datadog.yaml
```

Ensure the following entries exist:

```yaml theme={null}
api_key: XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
site: datadoghq.com
tags:
  - env:prod

apm_config:
  enabled: true
  env: prod
```

2. Restart the agent:

```bash theme={null}
sudo systemctl restart datadog-agent
```

3. Verify APM listener:

```bash theme={null}
sudo datadog-agent status | grep -A10 "APM Agent"
```

* Should show listener running on `127.0.0.1:8126`.

***

### 4. Python Application Setup (`example-app`)

**Directory structure example:**

```
/home/ec2-user/example-app/
├── venv/
├── main.py
├── requirements.txt
```

1. Activate virtual environment and install dependencies:

```bash theme={null}
source /home/ec2-user/example-app/venv/bin/activate
pip install ddtrace uvicorn fastapi
```

***

### 5. Create Systemd Service for Python App

1. Create the unit file `/etc/systemd/system/example-app.service`:

```ini theme={null}
[Unit]
Description=Example Python FastAPI Application
After=network.target

[Service]
User=root
Group=root
WorkingDirectory=/home/ec2-user/example-app
Environment=DD_AGENT_HOST=127.0.0.1
Environment=DD_SERVICE=example-app
Environment=DD_ENV=prod
Environment=DD_VERSION=1.0.0
Environment=DD_TRACE_REMOVE_INTEGRATION_SERVICE_NAMES=true
ExecStart=/home/ec2-user/example-app/venv/bin/ddtrace-run /home/ec2-user/example-app/venv/bin/uvicorn main:app --host 0.0.0.0 --port 8000
Restart=always
RestartSec=5
StandardOutput=journal
StandardError=journal

[Install]
WantedBy=multi-user.target
```

2. Enable and start the service:

```bash theme={null}
sudo systemctl daemon-reload
sudo systemctl enable example-app
sudo systemctl start example-app
sudo journalctl -u example-app -f
```

> `ddtrace-run` ensures traces from the Python app are sent to the local Datadog Agent.
> Logs are captured in the systemd journal and can be viewed using `journalctl`.

***

### 6. Verification

1. **Host Metrics:**

   * Go to Datadog Dashboard → Host Metrics
   * Verify CPU, memory, disk, and network metrics from the EC2 instance.

2. **APM Traces:**

   * Go to Datadog APM → Tracing Dashboard
   * Requests to your FastAPI app should appear automatically with traces.

3. **Agent Status:**

   ```bash theme={null}
   sudo datadog-agent status
   ```

   Ensure:

   * Forwarder API key is valid.
   * Core checks (system.cpu, system.mem, etc.) show OK.
   * APM Agent listener is running.

***

### ✅ References

* [Datadog Agent Installation for Linux](https://docs.datadoghq.com/agent/)
* [Datadog Custom Dashboards](https://docs.datadoghq.com/dashboards/)
* [Datadog APM Tracing](https://docs.datadoghq.com/tracing/)