# Intelligent Disk Cleaner

A zero-dependency Python script for Linux servers that prevents disk exhaustion by monitoring usage and intelligently cleaning up log files.

## Key Features

1.  **Zero External Dependencies**: Runs on standard Python 3 libraries. No `pip install` needed.
2.  **Dual Thresholds**:
    *   **Warning (80%)**: Alerts admins to high usage and identifies the largest open file (suspected culprit) without modifying any files.
    *   **Critical (95%)**: Triggers active cleanup to recover space immediately.
3.  **Intelligent Truncation**: Safely shrinks large active log files in-place by removing the oldest 50% of data, preserving the process file handle.
4.  **Fallback Cleanup**: If active logs cannot be shrunk, iteratively deletes the oldest rotated log files first.
5.  **Spam Prevention**: Rate-limits email notifications to once every 8 hours per disk volume.

## Requirements

*   **Operating System**: Linux (relies on `/proc` filesystem for process analysis).
*   **Runtime**: Python 3.6+.

## Configuration

Open `disk_cleaner.py` and configure the settings at the top of the file:

```python
# --- Configuration ---
THRESHOLD_PERCENT = 95.0          # Critical cleanup trigger
WARNING_THRESHOLD_PERCENT = 80.0  # Warning email trigger
RATE_LIMIT_SECONDS = 8 * 3600     # 8 hours cooldown

# Email Settings
SMTP_SERVER = "smtp.example.com"
SMTP_PORT = 25
EMAIL_FROM = "alerts@example.com"
EMAIL_TO = ["admins@example.com"]
```

## Usage

### Manual Execution
Run with root privileges to ensure access to all system processes (required for accurate open file detection):

```bash
sudo python3 disk_cleaner.py
```

### Automation (Cron)
To monitor continuously, add a cron job (e.g., run hourly).

1.  Open root crontab:
    ```bash
    sudo crontab -e
    ```

2.  Add the schedule:
    ```bash
    # Run every hour at minute 0
    0 * * * * /usr/bin/python3 /opt/scripts/disk_cleaner.py >> /var/log/disk_cleaner.log 2>&1
    ```

## Logic Flow

1.  **Check Usage**: Scans all mounted partitions (ignoring pseudo-filesystems).
2.  **Evaluate State**:
    *   **< 80%**: Healthy. Exit.
    *   **80% - 94% (Warning)**: Start scan. Find the largest file held open by any process. Send a "WARNING" email with the file path and size. **No action taken.**
    *   **> 95% (Critical)**: Start scan.
        *   **Strategy A**: additional checks confirm files are logs. Truncate the largest active log file by 50%. Check if space is recovered.
        *   **Strategy B**: If A fails/insufficient, find rotated logs (e.g., `.log.1`, `.gz`) and delete the oldest ones until usage drops.
    *   **Action Taken**: Send "URGENT" email detailing the cleanup.
    *   **Action Failed**: If space cannot be freed, send "CRITICAL" email with the largest suspect file.
3.  **Rate Limit**: Before sending any email, check the state file (`/tmp/disk_cleaner_state.json`). If an email was sent for this volume in the last 8 hours, suppress the notification.