# apt-ostree Container Installation Fix

## Problem Solved
The `apt-ostree` package was failing to install in container environments due to systemd service configuration attempts that require a running systemd instance.

## Root Cause
The original `check_systemd()` function only checked if the `systemctl` command existed, but didn't verify:
1. If systemd was actually running as PID 1
2. If the system was in a container environment
3. If the systemd D-Bus interface was available

## Solution Implemented
Updated the `check_systemd()` function in `debian/apt-ostree.postinst` to:

1. **Check for systemctl command availability**
2. **Detect container environments** using multiple indicators:
   - `/.dockerenv` file (Docker)
   - `container` environment variable (Podman, Docker, etc.)
   - `/run/.containerenv` file (Podman)
   - Docker in `/proc/1/cgroup` (additional Docker detection)
3. **Verify systemd is running as PID 1** using `ps -p 1 -o comm=`
4. **Check systemd D-Bus availability** using `systemctl is-system-running`

## Key Changes

### Before (Original Code)
```bash
check_systemd() {
    if ! command -v systemctl >/dev/null 2>&1; then
        log "Warning: systemd not available, skipping service setup"
        return 1
    fi
    return 0
}
```

### After (Fixed Code)
```bash
check_systemd() {
    # Check if systemctl command exists
    if ! command -v systemctl >/dev/null 2>&1; then
        log "Warning: systemd not available, skipping service setup"
        return 1
    fi
    
    # Check if we're in a container environment
    if [ -f /.dockerenv ] || [ -n "${container:-}" ] || [ -f /run/.containerenv ] || \
       ([ -f /proc/1/cgroup ] && grep -q docker /proc/1/cgroup 2>/dev/null); then
        log "Warning: Running in container environment, skipping systemd service setup"
        return 1
    fi
    
    # Check if systemd is actually running as PID 1
    if ! ps -p 1 -o comm= | grep -q systemd; then
        log "Warning: systemd not running as PID 1, skipping service setup"
        return 1
    fi
    
    # Check if systemd D-Bus is available
    if ! systemctl is-system-running >/dev/null 2>&1; then
        log "Warning: systemd not running, skipping service setup"
        return 1
    fi
    
    return 0
}
```

## Additional Improvements
- Enhanced `setup_service()` function to provide helpful manual configuration instructions when skipping systemd setup
- Added proper parentheses to fix logical operator precedence in container detection

## Testing Results
✅ **Container Environment**: Package installs successfully, skips systemd configuration gracefully
✅ **Real System**: Package installs and configures systemd services normally
✅ **Podman Container**: Verified working with actual Podman container build

## Files Modified
- `debian/apt-ostree.postinst` - Updated `check_systemd()` and `setup_service()` functions

## Impact
- **Fixes**: Container builds and CI/CD pipelines that install apt-ostree
- **Maintains**: Full functionality on real systems with systemd
- **Improves**: User experience with clear error messages and manual configuration instructions

## Verification Commands
```bash
# Test in container (should skip systemd)
docker run --rm -it debian:unstable bash -c "apt update && apt install -y apt-ostree"

# Test on real system (should configure systemd)
apt install -y apt-ostree && systemctl status apt-ostreed
```

## Status
✅ **COMPLETED** - Fix implemented and tested successfully