prose-contracts/scripts/disk-gc-scan.py

#!/usr/bin/env python3
"""disk-gc-scan — deterministic disk usage probe for fleet guests.

This is the executable scanner side of `disk-gc-threat-response.prose.md`. It exists
so reachability verdicts are deterministic and every rendered field traces to a
named probe command.

DESIGN PRINCIPLES (per task disk-gc-probe-false-unreachable-20260913):
1. REACHABILITY VERDICTS ARE DETERMINISTIC:
   - Retry once on failure before declaring unreachable
   - Always name the probe target (guest, host, access method) on the line it prints
   - Never render a failed probe as a bare service/guest verdict — print the failure kind

2. PER-GUEST ACCESS METHOD CANNOT BE MIS-SELECTED:
   - CT 105 (kagentz) = ssh root@kagentz (NOT pct exec 105)
   - VM 109 (docker-vm) = ssh root@192.168.68.7 (NOT pct)
   - All other CTs = pct-run <ct_id> (which uses pct exec)
   - The access method is selected from a per-guest map so the wrong path cannot be
     picked by an executor improvising

3. EVERY RENDERED FIELD AUDITED:
   - For each guest, print the probe command that produced the figure
   - If a figure comes from a different kind of measurement than the column claims,
     name it explicitly

4. FIX A (CWD independence): Resolve repo-relative files from the script's own
   location, not the caller's CWD.
   FIX B (df columns): Parse df output correctly and print labelled, human-readable
   output.

Usage:
    disk-gc-scan.py              # scan all guests
    disk-gc-scan.py --json       # machine-readable output

Exit codes: 0 ok (all guests probed), 1 probe error
"""
from __future__ import annotations

import json
import pathlib
import subprocess
import sys
import time
import os
from dataclasses import dataclass
from typing import Optional

# Resolve repo-relative files from the script's own location, not the caller's CWD
SCRIPT_DIR = pathlib.Path(__file__).resolve().parent
HELPER_PCT_RUN = SCRIPT_DIR / "pct-run.sh"

# Per-guest access method map. This is the authoritative source for how to reach
# each guest — the contract's prose documentation must match this map.
#
# Access methods:
#   - "pct-run": use pct-run.sh <ct_id> (pct exec via SSH to node)
#   - "ssh-host": use ssh root@<hostname>
#   - "ssh-ip": use ssh root@<ip>

@dataclass
class Guest:
    """A guest to probe."""
    ct_id: str
    hostname: str
    ip: Optional[str]
    node: str
    access_method: str  # "pct-run", "ssh-host", "ssh-ip"
    probe_target: str   # human-readable target name for the probe line

    @property
    def is_reachable(self) -> bool:
        return self.probe_result is not None and self.probe_result.exit_code == 0

    @property
    def usage_pct(self) -> Optional[float]:
        return self.probe_result.usage_pct if self.probe_result else None

    @property
    def usage_str(self) -> Optional[str]:
        return self.probe_result.usage_str if self.probe_result else None

    probe_result: Optional["ProbeResult"] = None


@dataclass
class ProbeResult:
    """Result of probing a guest."""
    exit_code: int
    usage_pct: Optional[float]
    usage_str: Optional[str]
    probe_cmd: str
    failure_kind: Optional[str]  # "timeout", "ssh-auth", "no-route", "command-not-found", None

    @property
    def is_reachable(self) -> bool:
        return self.exit_code == 0


# Fleet inventory (verified against pvesh /cluster/resources 2026-09-12)
GUESTS: list[Guest] = [
    # amdpve (192.168.68.15)
    Guest(ct_id="105", hostname="kagentz", ip="192.168.68.105", node="amdpve",
          access_method="ssh-host", probe_target="kagentz (CT 105, amdpve)"),
    Guest(ct_id="113", hostname="baggy", ip="192.168.68.113", node="amdpve",
          access_method="pct-run", probe_target="baggy (CT 113, amdpve)"),
    Guest(ct_id="115", hostname="scottdenya", ip="192.168.68.115", node="amdpve",
          access_method="pct-run", probe_target="scottdenya (CT 115, amdpve)"),
    Guest(ct_id="120", hostname="adguard2", ip="192.168.68.120", node="amdpve",
          access_method="pct-run", probe_target="adguard2 (CT 120, amdpve)"),
    # minipve (192.168.68.12)
    Guest(ct_id="112", hostname="tanko", ip="192.168.68.112", node="minipve",
          access_method="pct-run", probe_target="tanko (CT 112, minipve)"),
    Guest(ct_id="100", hostname="abiba", ip="192.168.68.100", node="minipve",
          access_method="pct-run", probe_target="abiba (CT 100, minipve)"),
    Guest(ct_id="102", hostname="adguard", ip="192.168.68.102", node="minipve",
          access_method="pct-run", probe_target="adguard (CT 102, minipve)"),
    Guest(ct_id="104", hostname="authentik", ip="192.168.68.104", node="minipve",
          access_method="pct-run", probe_target="authentik (CT 104, minipve)"),
    Guest(ct_id="110", hostname="gitea", ip="192.168.68.110", node="minipve",
          access_method="pct-run", probe_target="gitea (CT 110, minipve)"),
    Guest(ct_id="116", hostname="syslog-api", ip="192.168.68.116", node="minipve",
          access_method="pct-run", probe_target="syslog-api (CT 116, minipve)"),
    Guest(ct_id="119", hostname="infisical-vault", ip="192.168.68.119", node="minipve",
          access_method="pct-run", probe_target="infisical-vault (CT 119, minipve)"),
    # storepve (192.168.68.6)
    Guest(ct_id="106", hostname="ra-h-os", ip="192.168.68.106", node="storepve",
          access_method="pct-run", probe_target="ra-h-os (CT 106, storepve)"),
    Guest(ct_id="107", hostname="proxmox-backup", ip="192.168.68.107", node="storepve",
          access_method="pct-run", probe_target="proxmox-backup (CT 107, storepve)"),
    Guest(ct_id="108", hostname="media", ip="192.168.68.108", node="storepve",
          access_method="pct-run", probe_target="media (CT 108, storepve)"),
    Guest(ct_id="111", hostname="tdunna", ip="192.168.68.129", node="storepve",
          access_method="pct-run", probe_target="tdunna (CT 111, storepve)"),
    Guest(ct_id="117", hostname="zulip", ip="192.168.68.117", node="storepve",
          access_method="pct-run", probe_target="zulip (CT 117, storepve)"),
    Guest(ct_id="118", hostname="jdownloader", ip="192.168.68.118", node="storepve",
          access_method="pct-run", probe_target="jdownloader (CT 118, storepve)"),
    # KVM VMs (direct SSH)
    Guest(ct_id="109", hostname="docker-vm", ip="192.168.68.7", node="storepve",
          access_method="ssh-ip", probe_target="docker-vm (CT 109, KVM VM)"),
]

# GPU bare-metal hosts
GPU_HOSTS = [
    {"hostname": "acerpve", "ip": "192.168.68.9", "gpu": "RTX 3090",
     "probe_target": "RTX 3090 (bare metal .9)"},
    {"hostname": "ocupve", "ip": "192.168.68.110", "gpu": "RTX 5070",
     "probe_target": "RTX 5070 (bare metal .110)"},
    {"hostname": "amdpve", "ip": "192.168.68.15", "gpu": "Strix Halo",
     "probe_target": "Strix Halo (bare metal .15)"},
]

CONNECT_TIMEOUT = 5
SSH_OPTS = "-o BatchMode=yes -o ConnectTimeout=" + str(CONNECT_TIMEOUT)

# Host filesystem thresholds (from contract)
HOST_THRESHOLDS = {
    "WARN": 85,
    "AMBER": 90,
    "RED": 95,
}

# State file path (absolute, so execution context doesn't matter)
STATE_FILE = pathlib.Path(__file__).resolve().parent.parent / "state" / "host-disk-bands.json"

# PVE nodes to probe for host filesystems
HOST_NODES = [
    {"hostname": "acerpve", "ip": "192.168.68.9"},
    {"hostname": "amdpve", "ip": "192.168.68.15"},
    {"hostname": "storepve", "ip": "192.168.68.6"},
    {"hostname": "minipve", "ip": "192.168.68.12"},
    {"hostname": "ocupve", "ip": "192.168.68.5"},
]


def run_cmd(cmd: str, timeout: int = 30) -> tuple[int, str, str]:
    """Run a command and return (exit_code, stdout, stderr)."""
    try:
        result = subprocess.run(
            cmd, shell=True, capture_output=True, text=True, timeout=timeout
        )
        return result.returncode, result.stdout.strip(), result.stderr.strip()
    except subprocess.TimeoutExpired:
        return 124, "", "timeout"
    except Exception as e:
        return 1, "", str(e)


def probe_guest(guest: Guest) -> ProbeResult:
    """Probe a single guest and return the result.

    Access method is selected from guest.access_method:
      - "pct-run": pct-run.sh <ct_id> "df -P / | tail -1"
      - "ssh-host": ssh root@<hostname> "df -P / | tail -1"
      - "ssh-ip": ssh root@<ip> "df -P / | tail -1"
    """
    df_cmd = "df -P / | tail -1"

    if guest.access_method == "pct-run":
        # Use absolute path to helper so CWD doesn't matter
        probe_cmd = f'bash {HELPER_PCT_RUN} {guest.ct_id} "{df_cmd}"'
    elif guest.access_method == "ssh-host":
        probe_cmd = f'ssh {SSH_OPTS} root@{guest.hostname} "{df_cmd}"'
    elif guest.access_method == "ssh-ip":
        probe_cmd = f'ssh {SSH_OPTS} root@{guest.ip} "{df_cmd}"'
    else:
        raise ValueError(f"unknown access_method: {guest.access_method}")

    # Check helper exists and is readable BEFORE probing (for pct-run guests)
    # This prevents scanner errors from being rendered as guest verdicts
    if guest.access_method == "pct-run":
        if not HELPER_PCT_RUN.exists():
            print(f"SCANNER ERROR: helper not found: {HELPER_PCT_RUN}", file=sys.stderr)
            sys.exit(1)
        if not os.access(str(HELPER_PCT_RUN), os.R_OK):
            print(f"SCANNER ERROR: helper not readable: {HELPER_PCT_RUN}", file=sys.stderr)
            sys.exit(1)

    # Retry once on failure before declaring unreachable
    for attempt in range(2):
        exit_code, stdout, stderr = run_cmd(probe_cmd, timeout=15)

        if exit_code == 0:
            # Parse df output: Filesystem 1024-blocks Used Available Capacity Mounted on
            # parts[0]=Filesystem, parts[1]=Total (1K blocks), parts[2]=Used, parts[3]=Available, parts[4]=Capacity
            parts = stdout.split()
            if len(parts) >= 5:
                capacity_str = parts[4]  # e.g., "34%"
                usage_pct = float(capacity_str.rstrip("%"))
                total_blocks = int(parts[1])
                used_blocks = int(parts[2])
                avail_blocks = int(parts[3])
                # Convert to human-readable units
                def to_gb(blocks: int) -> float:
                    return blocks / (1024 * 1024)
                total_gb = to_gb(total_blocks)
                used_gb = to_gb(used_blocks)
                avail_gb = to_gb(avail_blocks)
                # FIX B: print labelled, unambiguous output
                usage_str = f"{capacity_str} ({used_gb:.1f}G used of {total_gb:.1f}G total, {avail_gb:.1f}G free)"
                return ProbeResult(
                    exit_code=0,
                    usage_pct=usage_pct,
                    usage_str=usage_str,
                    probe_cmd=probe_cmd,
                    failure_kind=None,
                )
            else:
                # Unexpected output format
                return ProbeResult(
                    exit_code=1,
                    usage_pct=None,
                    usage_str=None,
                    probe_cmd=probe_cmd,
                    failure_kind="parse-error",
                )
        else:
            # Classify failure kind
            if exit_code == 124:
                failure_kind = "timeout"
            elif "Connection timed out" in stderr or "timed out" in stderr:
                failure_kind = "timeout"
            elif "Permission denied" in stderr or "password" in stderr.lower():
                failure_kind = "ssh-auth"
            elif "No route to host" in stderr or "unreachable" in stderr:
                failure_kind = "no-route"
            elif "Connection refused" in stderr:
                failure_kind = "conn-refused"
            elif "command not found" in stderr.lower() or "No such file" in stderr:
                failure_kind = "command-not-found"
            else:
                failure_kind = f"ssh-exit-{exit_code}"

            # Retry once
            if attempt == 0:
                time.sleep(1)
                continue
            return ProbeResult(
                exit_code=exit_code,
                usage_pct=None,
                usage_str=None,
                probe_cmd=probe_cmd,
                failure_kind=failure_kind,
            )

    # Should not reach here, but just in case
    return ProbeResult(
        exit_code=1,
        usage_pct=None,
        usage_str=None,
        probe_cmd=probe_cmd,
        failure_kind="unknown",
    )


def scan_fleet() -> list[dict]:
    """Scan all guests and return the results."""
    results = []
    for guest in GUESTS:
        probe_result = probe_guest(guest)
        guest.probe_result = probe_result

        row = {
            "target": guest.probe_target,
            "ct_id": guest.ct_id,
            "hostname": guest.hostname,
            "node": guest.node,
            "access_method": guest.access_method,
            "reachable": probe_result.is_reachable,
            "usage_pct": probe_result.usage_pct,
            "usage_str": probe_result.usage_str,
            "probe_cmd": probe_result.probe_cmd,
            "failure_kind": probe_result.failure_kind,
        }
        results.append(row)

    return results


def classify_band(usage_pct: float) -> str:
    """Classify a percentage into a band."""
    if usage_pct >= HOST_THRESHOLDS["RED"]:
        return "HOST-RED"
    elif usage_pct >= HOST_THRESHOLDS["AMBER"]:
        return "HOST-AMBER"
    elif usage_pct >= HOST_THRESHOLDS["WARN"]:
        return "HOST-WARN"
    else:
        return "GREEN"


def probe_host_filesystems() -> tuple[list[dict], dict[str, str]]:
    """Probe host filesystems on all PVE nodes.
    
    Returns:
        - List of host filesystem results
        - Dict of volume_key -> current_band (for state file)
    """
    results = []
    current_bands = {}
    
    for node in HOST_NODES:
        ip = node["ip"]
        hostname = node["hostname"]
        
        # Probe df for host filesystems
        probe_cmd = f'ssh {SSH_OPTS} root@{ip} "df -hP / /media/* tank 2>/dev/null | tail -n +2"'
        exit_code, stdout, stderr = run_cmd(probe_cmd, timeout=15)
        
        if exit_code != 0:
            results.append({
                "target": f"{hostname} ({ip})",
                "hostname": hostname,
                "ip": ip,
                "reachable": False,
                "volumes": [],
                "probe_cmd": probe_cmd,
                "failure_kind": "ssh-error",
            })
            continue
        
        # Parse df output and classify each volume
        volumes = []
        for line in stdout.splitlines():
            parts = line.split()
            if len(parts) < 6:
                continue
            
            dev, size, used, avail, pct_str, mount = parts[:6]
            pct = float(pct_str.rstrip("%"))
            band = classify_band(pct)
            
            # Volume type classification
            if mount.startswith("/media/"):
                vol_type = "media"
            elif mount == "/" or "pve" in dev:
                vol_type = "host-root"
            elif mount == "tank" or "tank" in mount:
                vol_type = "pbs-datastore"
            else:
                vol_type = "other"
            
            # Volume key for state file (host/volume)
            volume_key = f"{hostname}/{mount}"
            current_bands[volume_key] = band
            
            volumes.append({
                "mount": mount,
                "device": dev,
                "size": size,
                "used": used,
                "avail": avail,
                "pct": pct,
                "band": band,
                "type": vol_type,
            })
        
        results.append({
            "target": f"{hostname} ({ip})",
            "hostname": hostname,
            "ip": ip,
            "reachable": True,
            "volumes": volumes,
            "probe_cmd": probe_cmd,
            "failure_kind": None,
        })
    
    return results, current_bands


def read_state_file() -> Optional[dict[str, str]]:
    """Read the state file if it exists."""
    if not STATE_FILE.exists():
        return None
    try:
        with open(STATE_FILE) as f:
            return json.load(f)
    except (json.JSONDecodeError, IOError) as e:
        print(f"⚠️  State file exists but unreadable: {e}", file=sys.stderr)
        return {}


def write_state_file(bands: dict[str, str]) -> None:
    """Write the state file."""
    STATE_FILE.parent.mkdir(parents=True, exist_ok=True)
    try:
        with open(STATE_FILE, "w") as f:
            json.dump(bands, f, indent=2)
    except IOError as e:
        print(f"⚠️  State file write failed: {e}", file=sys.stderr)


def detect_transitions(current_bands: dict[str, str], prior_bands: Optional[dict[str, str]]) -> list[dict]:
    """Detect band transitions (current vs. prior)."""
    if prior_bands is None:
        # First run — no transitions, just establish baseline
        return []
    
    transitions = []
    # Check for volumes that moved to a higher band (escalation)
    for volume, current_band in current_bands.items():
        prior_band = prior_bands.get(volume, "GREEN")
        
        # Band ordering: GREEN < HOST-WARN < HOST-AMBER < HOST-RED
        band_order = {"GREEN": 0, "HOST-WARN": 1, "HOST-AMBER": 2, "HOST-RED": 3}
        
        if band_order[current_band] > band_order[prior_band]:
            transitions.append({
                "type": "escalation",
                "volume": volume,
                "from": prior_band,
                "to": current_band,
            })
        elif band_order[current_band] < band_order[prior_band]:
            transitions.append({
                "type": "recovery",
                "volume": volume,
                "from": prior_band,
                "to": current_band,
            })
    
    return transitions


def render_results(results: list[dict]) -> str:
    """Render scan results in human-readable format."""
    lines = []
    lines.append("=== Disk GC Scan ===")
    lines.append("")

    for row in results:
        if row["reachable"]:
            lines.append(f"  ✅ {row['target']}: {row['usage_str']}")
            lines.append(f"     probe: {row['probe_cmd']}")
        else:
            failure = row["failure_kind"] or "unknown"
            lines.append(f"  ❌ {row['target']}: UNREACHABLE ({failure})")
            lines.append(f"     probe: {row['probe_cmd']}")

    return "\n".join(lines)


def render_host_results(results: list[dict], transitions: list[dict], prior_bands: Optional[dict[str, str]]) -> str:
    """Render host filesystem results in human-readable format."""
    lines = []
    lines.append("")
    lines.append("=== Host Filesystem Bands ===")
    lines.append("")
    
    # Render transitions first (they're the actionable alerts)
    if prior_bands is None:
        lines.append("  (first run — recording baseline, no alerts)")
    elif not transitions:
        lines.append("  (no band changes since last scan)")
    else:
        for t in transitions:
            volume, from_band, to_band = t["volume"], t["from"], t["to"]
            if t["type"] == "escalation":
                lines.append(f"  ⚠️  {volume}: {from_band} → {to_band} (ESCALATION)")
            else:
                lines.append(f"  ✅ {volume}: {from_band} → {to_band} (RECOVERY)")
    
    # Render all volumes with their bands
    lines.append("")
    for node_result in results:
        if not node_result["reachable"]:
            lines.append(f"  ❌ {node_result['target']}: UNREACHABLE ({node_result['failure_kind']})")
            continue
        
        lines.append(f"  {node_result['target']}:")
        for vol in node_result["volumes"]:
            lines.append(f"    {vol['mount']} ({vol['type']}): {vol['pct']}% ({vol['used']}/{vol['size']}, {vol['avail']} free) -> {vol['band']}")
    
    return "\n".join(lines)


def main() -> int:
    import argparse

    ap = argparse.ArgumentParser(description="Deterministic disk usage probe for fleet guests and host filesystems.")
    ap.add_argument("--json", action="store_true", help="machine-readable output")
    ap.add_argument("--hosts-only", action="store_true", help="scan host filesystems only")
    ap.add_argument("--guests-only", action="store_true", help="scan guests only (skip host filesystems)")
    args = ap.parse_args()

    # Scan guests (unless --hosts-only)
    guest_results = []
    if not args.hosts_only:
        guest_results = scan_fleet()

    # Scan host filesystems (unless --guests-only)
    host_results = []
    current_bands = {}
    if not args.guests_only:
        host_results, current_bands = probe_host_filesystems()
        
        # Read prior state and detect transitions
        prior_bands = read_state_file()
        transitions = detect_transitions(current_bands, prior_bands)
        
        # Write new state
        write_state_file(current_bands)
    else:
        prior_bands = None
        transitions = []

    if args.json:
        # JSON output
        output = {
            "guests": guest_results,
            "hosts": host_results,
            "transitions": transitions,
            "prior_bands": prior_bands,
        }
        print(json.dumps(output, indent=2))
    else:
        # Human-readable output
        if guest_results:
            print(render_results(guest_results))
        
        if host_results:
            print(render_host_results(host_results, transitions, prior_bands))

    # Exit 0 if all probed (reachable or not), 1 if any probe error
    return 0


if __name__ == "__main__":
    sys.exit(main())