feat: add network monitors (ICMP/TCP/HTTP/DNS) (#2266)

Co-authored-by: xiaomiku01 <xiaomiku01@outlook.com>
Co-authored-by: henrygd <hank@henrygd.me>

internal/hub/network_monitors.go

@@ -0,0 +1,158 @@
+package hub
+
+import (
+	"strconv"
+	"time"
+
+	"github.com/henrygd/beszel/internal/entities/monitor"
+	"github.com/henrygd/beszel/internal/hub/systems"
+	"github.com/pocketbase/pocketbase/core"
+	"github.com/pocketbase/pocketbase/tools/types"
+)
+
+// generateMonitorID creates a stable hash ID for a monitor based on its configuration and the system it belongs to.
+func generateMonitorID(systemId string, config monitor.Config) string {
+	args := []string{systemId, config.Target, config.Protocol}
+	// only use port for TCP monitors, since for other protocols it's not relevant as standalone value
+	if config.Protocol == "tcp" {
+		args = append(args, strconv.FormatUint(uint64(config.Port), 10))
+	}
+	return systems.MakeStableHashId(args...)
+}
+
+// bindNetworkMonitorsEvents keeps monitor records and agent monitor state in sync.
+func bindNetworkMonitorsEvents(hub *Hub) {
+	// on create, make sure the id is set to a stable hash
+	hub.OnRecordCreate("network_monitors").BindFunc(func(e *core.RecordEvent) error {
+		systemID := e.Record.GetString("system")
+		config := monitorConfigFromRecord(e.Record)
+		id := generateMonitorID(systemID, *config)
+		e.Record.Set("id", id)
+		return e.Next()
+	})
+
+	// sync monitor to agent on creation and persist the first result immediately when available
+	hub.OnRecordAfterCreateSuccess("network_monitors").BindFunc(func(e *core.RecordEvent) error {
+		err := e.Next()
+		if err != nil {
+			return err
+		}
+		if !e.Record.GetBool("enabled") {
+			return nil
+		}
+		// If connected, run the monitor immediately. Paused systems may be absent
+		// from the manager; their monitors will sync when they reconnect.
+		system, err := hub.sm.GetSystem(e.Record.GetString("system"))
+		if err == nil && system.Status == "up" {
+			go hub.upsertNetworkMonitor(e.Record, true)
+		}
+		return nil
+	})
+
+	// On API update requests, if the monitor config changed in a way that requires a new ID, create a new
+	// record with the new ID and delete the old one. Otherwise, just update the existing monitor on the agent.
+	hub.OnRecordUpdateRequest("network_monitors").BindFunc(func(e *core.RecordRequestEvent) error {
+		systemID := e.Record.GetString("system")
+		// only tcp uses port - set other protocols port to zero
+		if e.Record.GetString("protocol") != "tcp" {
+			e.Record.Set("port", 0)
+		}
+		ID := generateMonitorID(systemID, *monitorConfigFromRecord(e.Record))
+		if ID != e.Record.Id {
+			newRecord := copyMonitorToNewRecord(e.Record, ID)
+			if err := e.App.Save(newRecord); err != nil {
+				return err
+			}
+			if err := e.App.Delete(e.Record); err != nil {
+				return err
+			}
+			return nil
+		}
+		err := e.Next()
+		if err != nil {
+			return err
+		}
+		if e.Record.GetBool("enabled") {
+			// if the monitor is enabled, sync the updated config to the agent now
+			runNow := !e.Record.Original().GetBool("enabled")
+			err = hub.upsertNetworkMonitor(e.Record, runNow)
+		} else {
+			// if the monitor is paused, remove it from the agent
+			err = hub.deleteNetworkMonitor(e.Record)
+		}
+		if err != nil {
+			hub.Logger().Warn("failed to sync updated monitor", "system", systemID, "monitor", e.Record.Id, "err", err)
+		}
+		return nil
+	})
+
+	// sync monitor to agent on delete
+	hub.OnRecordAfterDeleteSuccess("network_monitors").BindFunc(func(e *core.RecordEvent) error {
+		if err := hub.deleteNetworkMonitor(e.Record); err != nil {
+			hub.Logger().Warn("failed to delete monitor on agent", "system", e.Record.GetString("system"), "monitor", e.Record.Id, "err", err)
+		}
+		return e.Next()
+	})
+}
+
+// monitorConfigFromRecord builds a monitor config from a network_monitors record.
+func monitorConfigFromRecord(record *core.Record) *monitor.Config {
+	return &monitor.Config{
+		ID:       record.Id,
+		Target:   record.GetString("target"),
+		Protocol: record.GetString("protocol"),
+		Port:     uint16(record.GetInt("port")),
+		Interval: uint16(record.GetInt("interval")),
+	}
+}
+
+// setMonitorResultFields stores the latest monitor result values on the record.
+func setMonitorResultFields(record *core.Record, result monitor.Result) {
+	nowString := time.Now().UTC().Format(types.DefaultDateLayout)
+	record.Set("res", result.AvgResponse)
+	record.Set("resAvg1h", result.AvgResponse1h)
+	record.Set("resMin1h", result.MinResponse1h)
+	record.Set("resMax1h", result.MaxResponse1h)
+	record.Set("loss1h", result.PacketLoss1h)
+	record.Set("updated", nowString)
+}
+
+// copyMonitorToNewRecord creates a new record with the same field values as the old one.
+// This is used when the monitor config changes in a way that requires a new ID, so we need
+// to create a new record with the new ID and delete the old one.
+func copyMonitorToNewRecord(oldRecord *core.Record, newID string) *core.Record {
+	collection := oldRecord.Collection()
+	newRecord := core.NewRecord(collection)
+	newRecord.Id = newID
+	fields := []string{"system", "target", "protocol", "port", "interval", "enabled"}
+	for _, field := range fields {
+		newRecord.Set(field, oldRecord.Get(field))
+	}
+	return newRecord
+}
+
+// upsertNetworkMonitor creates or updates the record's monitor on the target system. If runNow
+// is true, it will also trigger an immediate monitor run and update the record with the result.
+func (h *Hub) upsertNetworkMonitor(record *core.Record, runNow bool) error {
+	systemID := record.GetString("system")
+	system, err := h.sm.GetSystem(systemID)
+	if err != nil {
+		return err
+	}
+	result, err := system.UpsertNetworkMonitor(*monitorConfigFromRecord(record), runNow)
+	if err != nil || result == nil {
+		return err
+	}
+	setMonitorResultFields(record, *result)
+	return h.App.SaveNoValidate(record)
+}
+
+// deleteNetworkMonitor removes the record's monitor from the target system.
+func (h *Hub) deleteNetworkMonitor(record *core.Record) error {
+	systemID := record.GetString("system")
+	system, err := h.sm.GetSystem(systemID)
+	if err != nil {
+		return err
+	}
+	return system.DeleteNetworkMonitor(record.Id)
+}