Mount Exporter

A Prometheus exporter for monitoring filesystem mount point availability by calling the system findmnt command and exposing metrics indicating whether configured mount points are currently active.

Overview

Mount Exporter provides critical monitoring for storage infrastructure by:

• Monitoring configured filesystem mount points
• Exposing Prometheus-compatible metrics
• Supporting automated alerting when mount points become unavailable
• Running as a single binary with minimal dependencies

Features

• ✅ Mount Point Monitoring: Uses findmnt command to verify mount status
• ✅ Prometheus Metrics: Exposes metrics in standard Prometheus format
• ✅ Configuration Management: YAML-based configuration with validation
• ✅ Health Checks: Built-in health endpoint for monitoring
• ✅ Structured Logging: Configurable logging levels and formats
• ✅ Graceful Shutdown: Proper signal handling and cleanup
• ✅ Container Ready: Docker support with health checks
• ✅ Production Ready: systemd service template included

Quick Start

Binary Installation

1. Download the latest release

   wget https://github.com/mount-exporter/mount-exporter/releases/latest/download/mount-exporter-linux-amd64
   chmod +x mount-exporter-linux-amd64
   sudo mv mount-exporter-linux-amd64 /usr/local/bin/mount-exporter

2. Create configuration

   sudo mkdir -p /etc/mount-exporter
   sudo cp config.yaml /etc/mount-exporter/config.yaml
   sudo nano /etc/mount-exporter/config.yaml

3. Run the exporter

   mount-exporter -config /etc/mount-exporter/config.yaml

Docker Installation

# Build the image
docker build -t mount-exporter:latest .

# Run with default configuration
docker run -d \
  --name mount-exporter \
  -p 8080:8080 \
  -v $(pwd)/examples/config.yaml:/etc/mount-exporter/config.yaml:ro \
  mount-exporter:latest

# Or with custom configuration
docker run -d \
  --name mount-exporter \
  -p 8080:8080 \
  -v /path/to/your/config.yaml:/etc/mount-exporter/config.yaml:ro \
  mount-exporter:latest

Systemd Service

# Copy the service file
sudo cp examples/mount-exporter.service /etc/systemd/system/
sudo cp examples/config.yaml /etc/mount-exporter/

# Create mount-exporter user
sudo useradd -r -s /bin/false mount-exporter
sudo chown -R mount-exporter:mount-exporter /etc/mount-exporter

# Enable and start the service
sudo systemctl daemon-reload
sudo systemctl enable mount-exporter
sudo systemctl start mount-exporter
sudo systemctl status mount-exporter

Configuration

The exporter uses YAML configuration files. Here's an example:

# server configuration
server:
  host: "0.0.0.0"      # Bind address
  port: 8080           # Port to listen on
  path: "/metrics"      # Metrics endpoint path

# Mount points to monitor
mount_points:
  - "/data"            # Data directory
  - "/var/log"         # System logs
  - "/mnt/backups"     # Backup mount point
  - "/home"            # User home directories

# Collection interval
interval: 30s          # How often to check mount points

# Logging configuration
logging:
  level: "info"        # Log level: debug, info, warn, error, fatal
  format: "json"       # Log format: json, text

Environment Variables

You can override configuration using environment variables:

• MOUNT_EXPORTER_HOST - Override server host
• MOUNT_EXPORTER_PORT - Override server port
• MOUNT_EXPORTER_PATH - Override metrics path
• MOUNT_EXPORTER_INTERVAL - Override collection interval
• MOUNT_EXPORTER_LOG_LEVEL - Override log level

Example:

export MOUNT_EXPORTER_PORT=9090
export MOUNT_EXPORTER_LOG_LEVEL=debug
mount-exporter

Metrics

The exporter exposes the following metrics on /metrics:

Mount Point Status

# HELP mount_exporter_mount_point_status Mount point availability status (1=mounted, 0=not mounted)
# TYPE mount_exporter_mount_point_status gauge
mount_exporter_mount_point_status{mount_point="/data"} 1
mount_exporter_mount_point_status{mount_point="/var/log"} 1
mount_exporter_mount_point_status{mount_point="/mnt/backups"} 0

Scrape Duration

# HELP mount_exporter_scrape_duration_seconds Time spent scraping mount point status
# TYPE mount_exporter_scrape_duration_seconds gauge
mount_exporter_scrape_duration_seconds{mount_point="/data"} 0.045
mount_exporter_scrape_duration_seconds{mount_point="/var/log"} 0.032

Application Health

# HELP mount_exporter_up Whether the mount exporter is healthy (1=healthy, 0=unhealthy)
# TYPE mount_exporter_up gauge
mount_exporter_up 1

Scrape Success

# HELP mount_exporter_scrape_success_total Total number of successful scrapes
# TYPE mount_exporter_scrape_success_total counter
mount_exporter_scrape_success_total{mount_point="/data"} 125
mount_exporter_scrape_success_total{mount_point="/var/log"} 125

Endpoints

• /metrics - Prometheus metrics endpoint
• /health - Health check endpoint (JSON format)
• /healthz - Alternative health check endpoint
• / - Basic information page

Health Check

The /health endpoint returns JSON response:

{"status": "healthy"}

If findmnt is not available or there are other issues:

{"status": "unhealthy", "error": "findmnt command not available"}

Command Line Options

mount-exporter [OPTIONS]

Options:
  -config string
        Path to configuration file (default: searches for config.yaml in common locations)
  -log-level string
        Override log level (debug, info, warn, error, fatal)
  -help
        Show help message
  -version
        Show version information

Configuration File Locations

The exporter looks for configuration files in this order:

1. config.yaml (current directory)
2. config.yml (current directory)
3. examples/config.yaml
4. examples/config.yml
5. /etc/mount-exporter/config.yaml
6. /etc/mount-exporter/config.yml

Troubleshooting

Common Issues

1. Permission Denied

   # Ensure the binary has execute permissions
   chmod +x mount-exporter

2. findmnt Command Not Found

   # Install util-linux package (Ubuntu/Debian)
   sudo apt-get update && sudo apt-get install util-linux
   
   # Install util-linux package (CentOS/RHEL)
   sudo yum install util-linux

3. Configuration Errors

   # Validate configuration
   mount-exporter -config config.yaml -log-level debug

4. Port Already in Use

   # Check what's using the port
   sudo netstat -tulpn | grep :8080
   
   # Use different port
   mount-exporter -config config.yaml
   # Set MOUNT_EXPORTER_PORT=9090 in config.yaml or environment variable

Logs

Check logs for detailed information:

# With systemd
sudo journalctl -u mount-exporter -f

# With Docker
docker logs -f mount-exporter

# Run in foreground for debugging
mount-exporter -log-level debug

Development

Building from Source

# Clone the repository
git clone https://github.com/mount-exporter/mount-exporter.git
cd mount-exporter

# Build the binary
make build

# Run tests
make test

# Run with coverage
make test-coverage

Project Structure

mount-exporter/
├── main.go              # Application entry point
├── config/              # Configuration package
│   ├── config.go        # Configuration handling
│   └── config_test.go   # Configuration tests
├── metrics/             # Metrics package
│   ├── collector.go     # Prometheus collector
│   └── collector_test.go # Metrics tests
├── server/              # HTTP server package
│   ├── server.go       # HTTP server
│   └── server_test.go  # Server tests
├── system/              # System integration
│   ├── findmnt.go      # findmnt wrapper
│   └── findmnt_test.go # System tests
├── test/                # Integration tests
│   └── integration_test.go
├── examples/            # Example configurations
│   ├── config.yaml      # Example config
│   └── mount-exporter.service
├── Dockerfile           # Container definition
├── Makefile             # Build automation
└── README.md            # This file

License

This project is licensed under the MIT License - see the LICENSE file for details.

Contributing

1. Fork the repository
2. Create a feature branch (git checkout -b feature/amazing-feature)
3. Commit your changes (git commit -m 'Add amazing feature')
4. Push to the branch (git push origin feature/amazing-feature)
5. Open a Pull Request

Support

• 📖 Documentation
• 🐛 Issues
• 💬 Discussions