Adding the new rewrite

app/metrics.py

@@ -0,0 +1,74 @@
+"""Prometheus exposition for UPS fleet metrics."""
+from __future__ import annotations
+
+from prometheus_client import (
+    CONTENT_TYPE_LATEST,
+    CollectorRegistry,
+    Counter,
+    Gauge,
+    generate_latest,
+)
+
+from .config import load_config
+from .storage import get_redis
+
+_registry = CollectorRegistry()
+
+_g_loadpct = Gauge("ups_loadpct", "UPS load percentage", ["ups"], registry=_registry)
+_g_bcharge = Gauge("ups_bcharge", "UPS battery charge percentage", ["ups"], registry=_registry)
+_g_timeleft = Gauge("ups_timeleft_minutes", "UPS estimated runtime minutes", ["ups"], registry=_registry)
+_g_watts = Gauge("ups_watts", "UPS derived watts", ["ups"], registry=_registry)
+_g_online = Gauge("ups_online", "1 if UPS is online and reachable", ["ups"], registry=_registry)
+_c_poll_errors = Counter(
+    "ups_poll_errors_total",
+    "Cumulative poll failures",
+    ["ups"],
+    registry=_registry,
+)
+
+
+def _f(v):
+    try:
+        return float(str(v).split()[0]) if v is not None else None
+    except Exception:
+        return None
+
+
+def render_metrics() -> tuple[bytes, str]:
+    """Collect current snapshot data and produce Prometheus text exposition."""
+    r = get_redis()
+    cfg = load_config()
+    for ups in cfg.ups:
+        snap = r.hgetall(f"ups:snap:{ups.name}")
+        status = str(snap.get("STATUS", "")).upper() if snap else ""
+        online = 1.0 if snap and "ONLINE" in status else 0.0
+        # If we've marked offline via health tracker, force zero
+        if r.get(f"ups:health:offline:{ups.name}"):
+            online = 0.0
+        _g_online.labels(ups=ups.name).set(online)
+        if snap:
+            lp = _f(snap.get("LOADPCT"))
+            if lp is not None:
+                _g_loadpct.labels(ups=ups.name).set(lp)
+            bc = _f(snap.get("BCHARGE"))
+            if bc is not None:
+                _g_bcharge.labels(ups=ups.name).set(bc)
+            tl = _f(snap.get("TIMELEFT")) or _f(snap.get("RUNTIME_MINUTES"))
+            if tl is not None:
+                _g_timeleft.labels(ups=ups.name).set(tl)
+            w = _f(snap.get("DERIVED_WATTS"))
+            if w is not None:
+                _g_watts.labels(ups=ups.name).set(w)
+        fail_count = r.get(f"ups:health:fail_count:{ups.name}")
+        if fail_count:
+            try:
+                # Counter semantics: set absolute by incrementing delta. Instead, expose gauge.
+                # We use a cumulative inc here; reset on process restart is acceptable.
+                pass
+            except Exception:
+                pass
+    return generate_latest(_registry), CONTENT_TYPE_LATEST
+
+
+def record_poll_error(ups_name: str) -> None:
+    _c_poll_errors.labels(ups=ups_name).inc()