feat(linux/mem): ✨ send oom events to Home Assistant

.vscode/settings.json

@@ -31,7 +31,8 @@
     "linux/media",
     "agent/sensor",
     "linux/cpu",
-    "linux/system"
+    "linux/system",
+    "linux/mem"
   ],
   "go.testFlags": ["-v"],
   "[markdown]": {

internal/agent/workers_linux.go

@@ -66,6 +66,7 @@ var sensorLaptopWorkersInitFuncs = []func(ctx context.Context) (*linux.EventSens
 
 // eventWorkersInitFuncs are event workers that produce events rather than sensors.
 var eventWorkersInitFuncs = []func(ctx context.Context) (*linux.EventWorker, error){
+	mem.NewOOMEventsWorker,
 	system.NewUserSessionEventsWorker,
 }
 

internal/linux/mem/oomEvents.go

@@ -0,0 +1,136 @@
+// Copyright 2024 Joshua Rich <[email protected]>.
+// SPDX-License-Identifier: MIT
+
+package mem
+
+import (
+	"context"
+	"fmt"
+	"log/slog"
+	"net/url"
+	"strings"
+
+	"github.com/davecgh/go-spew/spew"
+
+	"github.com/joshuar/go-hass-agent/internal/hass/event"
+	"github.com/joshuar/go-hass-agent/internal/linux"
+	"github.com/joshuar/go-hass-agent/internal/logging"
+	"github.com/joshuar/go-hass-agent/pkg/linux/dbusx"
+)
+
+const (
+	oomEventsWorkerID = "oom_events_worker"
+	oomDBusPath       = "/org/freedesktop/systemd1/unit"
+	unitPathPrefix    = "/org/freedesktop/systemd1/unit"
+	oomEventName      = "oom_event"
+)
+
+type oomEventData struct {
+	Process string `json:"process"`
+	PID     int    `json:"pid"`
+}
+
+type OOMEventsWorker struct {
+	triggerCh chan dbusx.Trigger
+	linux.EventWorker
+}
+
+func (w *OOMEventsWorker) Events(ctx context.Context) (<-chan event.Event, error) {
+	eventCh := make(chan event.Event)
+
+	go func() {
+		defer close(eventCh)
+
+		for {
+			select {
+			case <-ctx.Done():
+				return
+			case trigger := <-w.triggerCh:
+				props, err := dbusx.ParsePropertiesChanged(trigger.Content)
+				if err != nil {
+					logging.FromContext(ctx).Debug("Could not parse changed properties for unit.", slog.Any("error", err))
+					continue
+				}
+				// if !strings.HasPrefix(trigger.Path, unitPathPrefix+"/app-") {
+				// 	continue
+				// }
+				// Ignore events that don't indicate a result change.
+				if _, found := props.Changed["Result"]; !found {
+					continue
+				}
+
+				result, err := dbusx.VariantToValue[string](props.Changed["Result"])
+				if err != nil {
+					logging.FromContext(ctx).Debug("Could not parse result.", slog.Any("error", err))
+					continue
+				}
+
+				slog.Info("received event",
+					slog.String("path", trigger.Path),
+					slog.String("interface", props.Interface),
+					slog.Any("result", result),
+				)
+
+				if result == "oom-kill" {
+					spew.Dump(trigger)
+					// Naming is defined in
+					// https://systemd.io/DESKTOP_ENVIRONMENTS/. The strings seem
+					// to be percent-encoded with % replaced by _.
+					processStr, err := url.PathUnescape(strings.ReplaceAll(trigger.Path, "_", "%"))
+					if err != nil {
+						logging.FromContext(ctx).Debug("Could not unescape process path string.", slog.Any("error", err))
+					}
+
+					// Trim the D-Bus unit path prefix.
+					processStr = strings.TrimPrefix(processStr, unitPathPrefix+"/")
+					// Trim any "app-" prefix.
+					processStr = strings.TrimPrefix(processStr, "app-")
+					// Trim the ".service" suffix.
+					processStr = strings.TrimSuffix(processStr, ".service")
+					// Ignore the <RANDOM> string that might be appended.
+					processStr, _, _ = strings.Cut(processStr, "@")
+					// Get the PID.
+					pid, _ := dbusx.VariantToValue[int](props.Changed["MainPID"])
+					if pid == 0 {
+						continue
+					}
+					// Send an event.
+					eventCh <- event.Event{
+						EventType: oomEventName,
+						EventData: oomEventData{
+							Process: processStr,
+							PID:     pid,
+						},
+					}
+				}
+			}
+		}
+	}()
+
+	return eventCh, nil
+}
+
+func NewOOMEventsWorker(ctx context.Context) (*linux.EventWorker, error) {
+	worker := linux.NewEventWorker(oomEventsWorkerID)
+
+	bus, ok := linux.CtxGetSessionBus(ctx)
+	if !ok {
+		return worker, linux.ErrNoSessionBus
+	}
+
+	eventWorker := &OOMEventsWorker{}
+
+	triggerCh, err := dbusx.NewWatch(
+		dbusx.MatchPathNamespace(oomDBusPath),
+		dbusx.MatchPropChanged(),
+	).Start(ctx, bus)
+	if err != nil {
+		return nil, fmt.Errorf("unable to set-up D-Bus watch for OOM events: %w", err)
+	}
+
+	eventWorker.triggerCh = triggerCh
+
+	worker.EventType = eventWorker
+
+	return worker, nil
+}