c-relay/systemd/README.md

C-Relay Systemd Service

This directory contains files for running C-Relay as a Linux systemd service.

Files

• c-relay.service - Systemd service unit file
• install-systemd.sh - Installation script (run as root)
• uninstall-systemd.sh - Uninstallation script (run as root)
• README.md - This documentation file

Quick Start

1. Build the relay

# From the project root directory
make

2. Install as systemd service

# Run the installation script as root
sudo ./systemd/install-systemd.sh

3. Start the service

sudo systemctl start c-relay

4. Check status

sudo systemctl status c-relay

Service Details

Installation Location

• Binary: /opt/c-relay/c_relay_x86
• Database: /opt/c-relay/db/
• Service File: /etc/systemd/system/c-relay.service

User Account

• User: c-relay (system user, no shell access)
• Group: c-relay
• Home Directory: /opt/c-relay

Network Configuration

• Default Port: 8888
• Default Host: 127.0.0.1 (localhost only)
• WebSocket Endpoint: ws://127.0.0.1:8888

Configuration

Environment Variables

Edit /etc/systemd/system/c-relay.service to configure:

Environment=C_RELAY_CONFIG_PRIVKEY=your_private_key_here
Environment=C_RELAY_PORT=8888
Environment=C_RELAY_HOST=0.0.0.0

After editing, reload and restart:

sudo systemctl daemon-reload
sudo systemctl restart c-relay

Security Settings

The service runs with enhanced security:

• Runs as unprivileged c-relay user
• No new privileges allowed
• Protected system directories
• Private temporary directory
• Limited file access (only /opt/c-relay/db writable)
• Network restrictions to IPv4/IPv6 only

Service Management

Basic Commands

# Start service
sudo systemctl start c-relay

# Stop service
sudo systemctl stop c-relay

# Restart service
sudo systemctl restart c-relay

# Enable auto-start on boot
sudo systemctl enable c-relay

# Disable auto-start on boot
sudo systemctl disable c-relay

# Check service status
sudo systemctl status c-relay

# View logs (live)
sudo journalctl -u c-relay -f

# View logs (last 100 lines)
sudo journalctl -u c-relay -n 100

Log Management

Logs are handled by systemd's journal:

# View all logs
sudo journalctl -u c-relay

# View logs from today
sudo journalctl -u c-relay --since today

# View logs with timestamps
sudo journalctl -u c-relay --since "1 hour ago" --no-pager

Database Management

The database is automatically created on first run. Location: /opt/c-relay/db/c_nostr_relay.db

Backup Database

sudo cp /opt/c-relay/db/c_nostr_relay.db /opt/c-relay/db/backup-$(date +%Y%m%d).db

Reset Database

sudo systemctl stop c-relay
sudo rm /opt/c-relay/db/c_nostr_relay.db*
sudo systemctl start c-relay

Updating the Service

Update Binary

1. Build new version: make
2. Stop service: sudo systemctl stop c-relay
3. Replace binary: sudo cp build/c_relay_x86 /opt/c-relay/
4. Set permissions: sudo chown c-relay:c-relay /opt/c-relay/c_relay_x86
5. Start service: sudo systemctl start c-relay

Update Service File

1. Stop service: sudo systemctl stop c-relay
2. Copy new service file: sudo cp systemd/c-relay.service /etc/systemd/system/
3. Reload systemd: sudo systemctl daemon-reload
4. Start service: sudo systemctl start c-relay

Uninstallation

Run the uninstall script to completely remove the service:

sudo ./systemd/uninstall-systemd.sh

This will:

• Stop and disable the service
• Remove the systemd service file
• Optionally remove the installation directory
• Optionally remove the c-relay user account

Troubleshooting

Service Won't Start

# Check detailed status
sudo systemctl status c-relay -l

# Check logs for errors
sudo journalctl -u c-relay --no-pager -l

Permission Issues

# Fix ownership of installation directory
sudo chown -R c-relay:c-relay /opt/c-relay

# Ensure binary is executable
sudo chmod +x /opt/c-relay/c_relay_x86

Port Already in Use

# Check what's using port 8888
sudo netstat -tulpn | grep :8888

# Or with ss command
sudo ss -tulpn | grep :8888

Database Issues

# Check database file permissions
ls -la /opt/c-relay/db/

# Check database integrity
sudo -u c-relay sqlite3 /opt/c-relay/db/c_nostr_relay.db "PRAGMA integrity_check;"

Custom Configuration

For advanced configurations, you can:

1. Modify the service file for different ports or settings
2. Use environment files: /etc/systemd/system/c-relay.service.d/override.conf
3. Configure log rotation with journald settings
4. Set up reverse proxy (nginx/apache) for HTTPS support

Security Considerations

• The service runs as a non-root user with minimal privileges
• Database directory is only writable by the c-relay user
• Consider firewall rules for the relay port
• For internet-facing relays, use reverse proxy with SSL/TLS
• Monitor logs for suspicious activity