feat: Serve resource usage metrics (#58)

* feat(resource-usage): Add lightweight resource metrics server

* fix(resource-usage): Handle None values for CPU count and usage percent

* fix(resource-usage): Subtract inactive fie from current memory

* refactor(resource-usage): Replace print statements with logging

* refactor(resource-usage): Simplify parsing logic and improve early returns

Author: mfranczel

deepnote_core/resources/scripts/resource_usage.py

@@ -0,0 +1,282 @@
+#!/usr/bin/env python3
+"""Lightweight resource metrics server."""
+
+import json
+import logging
+import os
+import threading
+import time
+from functools import partial
+from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
+from pathlib import Path
+from typing import Any, Optional
+
+try:
+    import psutil
+
+    HAS_PSUTIL = True
+except ImportError:
+    HAS_PSUTIL = False
+
+
+class ResourceMonitor:
+    """Monitors system resources via cgroups or psutil."""
+
+    def __init__(self, root_path: str = "/sys/fs/cgroup") -> None:
+        self.root = Path(root_path)
+        self.backend = self._detect_backend()
+        self._last_cpu_sec: Optional[float] = None
+        self._last_time: Optional[float] = None
+        self._lock = threading.Lock()
+
+    def _detect_backend(self) -> str:
+        if (self.root / "cgroup.controllers").exists():
+            return "cgroupv2"
+        if (self.root / "memory/memory.limit_in_bytes").exists():
+            return "cgroupv1"
+        if HAS_PSUTIL:
+            return "psutil"
+        return "none"
+
+    def _read_file(self, path: Path) -> Optional[str]:
+        try:
+            return path.read_text().strip()
+        except (FileNotFoundError, PermissionError, OSError):
+            return None
+
+    def get_memory(self) -> tuple[int, Optional[int]]:
+        """Returns (used_bytes, limit_bytes). Limit is None if unlimited."""
+        if self.backend == "cgroupv2":
+            current = self._parse_int(self.root / "memory.current", 0)
+            inactive_file = self._parse_memory_stat("inactive_file")
+            used = current - inactive_file
+            limit_str = self._read_file(self.root / "memory.max")
+            limit = self._parse_limit(limit_str, "max")
+            return used, limit
+
+        if self.backend == "cgroupv1":
+            used = self._parse_int(self.root / "memory/memory.usage_in_bytes", 0)
+            limit_str = self._read_file(self.root / "memory/memory.limit_in_bytes")
+            limit = self._parse_limit(limit_str, threshold=1_000_000_000_000_000)
+            return used, limit
+
+        if self.backend == "psutil":
+            proc = psutil.Process()
+            return proc.memory_info().rss, psutil.virtual_memory().total
+
+        return 0, None
+
+    def get_cpu(self) -> tuple[Optional[float], Optional[float]]:
+        """Returns (usage_percent, limit_cores)."""
+        usage_sec = self._get_cpu_seconds()
+        percent = self._calc_percent(usage_sec)
+        limit = self._get_cpu_limit()
+        return percent, limit
+
+    def _parse_int(self, path: Path, default: int = 0) -> int:
+        content = self._read_file(path)
+        if not content:
+            return default
+        try:
+            return int(content)
+        except ValueError:
+            return default
+
+    def _parse_limit(
+        self,
+        value: Optional[str],
+        unlimited_marker: Optional[str] = None,
+        threshold: Optional[int] = None,
+    ) -> Optional[int]:
+        if not value:
+            return None
+        if unlimited_marker and value == unlimited_marker:
+            return None
+        try:
+            parsed = int(value)
+            if threshold and parsed >= threshold:
+                return None
+            return parsed
+        except ValueError:
+            return None
+
+    def _parse_memory_stat(self, key: str) -> int:
+        """Parse a value from memory.stat file."""
+        content = self._read_file(self.root / "memory.stat")
+        if not content:
+            return 0
+        for line in content.splitlines():
+            if not line.startswith(key):
+                continue
+            parts = line.split()
+            if len(parts) < 2:
+                continue
+            try:
+                return int(parts[1])
+            except ValueError:
+                continue
+        return 0
+
+    def _get_cpu_seconds(self) -> float:
+        if self.backend == "cgroupv2":
+            content = self._read_file(self.root / "cpu.stat")
+            if not content:
+                return 0.0
+            for line in content.splitlines():
+                if not line.startswith("usage_usec"):
+                    continue
+                parts = line.split()
+                if len(parts) >= 2:
+                    return int(parts[1]) / 1_000_000.0
+            return 0.0
+
+        if self.backend == "cgroupv1":
+            content = self._read_file(self.root / "cpuacct/cpuacct.usage")
+            if not content:
+                return 0.0
+            return int(content) / 1_000_000_000.0
+
+        if self.backend == "psutil":
+            times = psutil.Process().cpu_times()
+            return times.user + times.system
+
+        return 0.0
+
+    def _get_cpu_limit(self) -> Optional[float]:
+        if self.backend == "cgroupv2":
+            content = self._read_file(self.root / "cpu.max")
+            if not content:
+                return None
+            parts = content.split()
+            if len(parts) < 2 or parts[0] == "max":
+                return None
+            try:
+                return int(parts[0]) / int(parts[1])
+            except (ValueError, ZeroDivisionError):
+                return None
+
+        if self.backend == "cgroupv1":
+            quota = self._parse_int(self.root / "cpu/cpu.cfs_quota_us", -1)
+            period = self._parse_int(self.root / "cpu/cpu.cfs_period_us", 0)
+            if quota <= 0 or period <= 0:
+                return None
+            return quota / period
+
+        if self.backend == "psutil":
+            cpu_count = psutil.cpu_count(logical=True)
+            return float(cpu_count) if cpu_count is not None else None
+
+        return None
+
+    def _calc_percent(self, current_sec: float) -> Optional[float]:
+        now = time.monotonic()
+        with self._lock:
+            if self._last_cpu_sec is None or self._last_time is None:
+                self._last_cpu_sec = current_sec
+                self._last_time = now
+                return None
+
+            time_delta = now - self._last_time
+            cpu_delta = current_sec - self._last_cpu_sec
+            self._last_cpu_sec = current_sec
+            self._last_time = now
+
+        if time_delta <= 0:
+            return 0.0
+        return (cpu_delta / time_delta) * 100.0
+
+
+class MetricsHandler(BaseHTTPRequestHandler):
+    """HTTP handler for resource metrics."""
+
+    def __init__(self, monitor: ResourceMonitor, *args: Any, **kwargs: Any) -> None:
+        self.monitor = monitor
+        super().__init__(*args, **kwargs)
+
+    def do_GET(self) -> None:
+        if self.path in ("/", "/resource-usage"):
+            self._send_metrics()
+        elif self.path == "/health":
+            self._send_text(200, "ok")
+        else:
+            self.send_error(404)
+
+    def _send_metrics(self) -> None:
+        mem_used, mem_limit = self.monitor.get_memory()
+        cpu_percent, cpu_limit = self.monitor.get_cpu()
+
+        env_limit = os.environ.get("MEM_LIMIT")
+        if env_limit:
+            try:
+                mem_limit = int(env_limit)
+            except ValueError:
+                pass
+
+        mem_util = None
+        if mem_limit and mem_limit > 0:
+            mem_util = round((mem_used / mem_limit) * 100, 2)
+
+        cpu_sat = None
+        if cpu_percent is not None and cpu_limit:
+            cpu_sat = round(cpu_percent / cpu_limit, 2)
+
+        data = {
+            "meta": {"backend": self.monitor.backend, "timestamp": time.time()},
+            "memory": {
+                "used_bytes": mem_used,
+                "limit_bytes": mem_limit,
+                "usage_percent": mem_util,
+            },
+            "cpu": {
+                "usage_percent": (
+                    round(cpu_percent, 2) if cpu_percent is not None else None
+                ),
+                "limit_cores": cpu_limit,
+                "saturation_percent": cpu_sat,
+            },
+        }
+        self._send_json(200, data)
+
+    def _send_json(self, code: int, data: dict[str, Any]) -> None:
+        body = json.dumps(data, indent=2).encode()
+        self._send_response(code, body, "application/json")
+
+    def _send_text(self, code: int, text: str) -> None:
+        self._send_response(code, text.encode(), "text/plain")
+
+    def _send_response(self, code: int, body: bytes, content_type: str) -> None:
+        self.send_response(code)
+        self.send_header("Content-Type", content_type)
+        self.send_header("Content-Length", str(len(body)))
+        self.send_header("X-Content-Type-Options", "nosniff")
+        self.end_headers()
+        self.wfile.write(body)
+
+    def log_message(self, msg_format: str, *args: Any) -> None:
+        logging.info(f"{self.address_string()} - {msg_format % args}")
+
+
+def main() -> None:
+    logging.basicConfig(
+        level=logging.INFO,
+        format="%(asctime)s - %(name)s - %(levelname)s - %(message)s",
+    )
+
+    port = int(os.environ.get("RESOURCE_USAGE_METRICS_PORT", 9104))
+    monitor = ResourceMonitor()
+    monitor.get_cpu()  # Initialize CPU baseline
+
+    handler = partial(MetricsHandler, monitor)
+    server = ThreadingHTTPServer(("0.0.0.0", port), handler)
+
+    logging.info(f"Starting server on port {port} (backend: {monitor.backend})")
+
+    try:
+        server.serve_forever()
+    except KeyboardInterrupt:
+        logging.info("Shutting down...")
+        server.server_close()
+
+
+if __name__ == "__main__":
+    main()

installer/__main__.py

@@ -382,6 +382,12 @@ def bootstrap():
     )
     all_actions.append(ExtraServerSpec(command=["python", prometheus_script]))
 
+    # Add resource usage server
+    resource_usage_script = os.path.join(
+        config_directory_path, "scripts", "resource_usage.py"
+    )
+    all_actions.append(ExtraServerSpec(command=["python", resource_usage_script]))
+
     # Execute all actions via the unified registry
     from .module.executor import run_actions_in_installer_env