eventsmap: encapsulate in cell

The cilium events map is used by the monitor.Agent. In preparation of
modularization of the agent, move the initialization of the eventsmap
into the hive.

Signed-off-by: David Bimmler <david.bimmler@isovalent.com>

daemon/cmd/datapath.go

@@ -14,7 +14,6 @@ import (
 	"github.com/vishvananda/netlink"
 
 	"github.com/cilium/cilium/pkg/cidr"
-	"github.com/cilium/cilium/pkg/common"
 	"github.com/cilium/cilium/pkg/controller"
 	datapathIpcache "github.com/cilium/cilium/pkg/datapath/ipcache"
 	"github.com/cilium/cilium/pkg/datapath/linux/ipsec"
@@ -29,7 +28,6 @@ import (
 	"github.com/cilium/cilium/pkg/labels"
 	"github.com/cilium/cilium/pkg/logging/logfields"
 	"github.com/cilium/cilium/pkg/maps/ctmap"
-	"github.com/cilium/cilium/pkg/maps/eventsmap"
 	"github.com/cilium/cilium/pkg/maps/fragmap"
 	ipcachemap "github.com/cilium/cilium/pkg/maps/ipcache"
 	"github.com/cilium/cilium/pkg/maps/ipmasq"
@@ -362,12 +360,6 @@ func (d *Daemon) initMaps() error {
 		log.WithError(err).Fatal("Unable to initialize service maps")
 	}
 
-	possibleCPUs := common.GetNumPossibleCPUs(log)
-
-	if err := eventsmap.InitMap(possibleCPUs); err != nil {
-		return fmt.Errorf("initializing events map: %w", err)
-	}
-
 	if err := policymap.InitCallMaps(option.Config.EnableEnvoyConfig); err != nil {
 		return fmt.Errorf("initializing policy map: %w", err)
 	}

pkg/datapath/cells.go

@@ -18,6 +18,7 @@ import (
 	"github.com/cilium/cilium/pkg/hive/cell"
 	ipcache "github.com/cilium/cilium/pkg/ipcache/types"
 	"github.com/cilium/cilium/pkg/maps"
+	"github.com/cilium/cilium/pkg/maps/eventsmap"
 	"github.com/cilium/cilium/pkg/option"
 	wg "github.com/cilium/cilium/pkg/wireguard/agent"
 	wgTypes "github.com/cilium/cilium/pkg/wireguard/types"
@@ -35,6 +36,9 @@ var Cell = cell.Module(
 	// Utime synchronizes utime from userspace to datapath via configmap.Map.
 	utime.Cell,
 
+	// The cilium events map, used by the monitor agent.
+	eventsmap.Cell,
+
 	cell.Provide(
 		newWireguardAgent,
 		newDatapath,

pkg/maps/eventsmap/cell.go

@@ -0,0 +1,51 @@
+// SPDX-License-Identifier: Apache-2.0
+// Copyright Authors of Cilium
+
+package eventsmap
+
+import (
+	"fmt"
+
+	"github.com/sirupsen/logrus"
+
+	"github.com/cilium/cilium/pkg/bpf"
+	"github.com/cilium/cilium/pkg/common"
+	"github.com/cilium/cilium/pkg/hive"
+	"github.com/cilium/cilium/pkg/hive/cell"
+)
+
+// Cell provides eventsmap.Map, which is the hive representation of the cilium
+// events perf event ring buffer.
+var Cell = cell.Module(
+	"events-map",
+	"eBPF ring buffer of cilium events",
+
+	cell.Provide(newEventsMap),
+)
+
+var (
+	MaxEntries int
+)
+
+type Map interface{}
+
+func newEventsMap(log logrus.FieldLogger, lifecycle hive.Lifecycle) bpf.MapOut[Map] {
+	eventsMap := &eventsMap{}
+
+	lifecycle.Append(hive.Hook{
+		OnStart: func(context hive.HookContext) error {
+			cpus := common.GetNumPossibleCPUs(log)
+			err := eventsMap.init(cpus)
+			if err != nil {
+				return fmt.Errorf("initializing events map: %w", err)
+			}
+			return nil
+		},
+		OnStop: func(context hive.HookContext) error {
+			// We don't currently care for cleaning up.
+			return nil
+		},
+	})
+
+	return bpf.NewMapOut(Map(eventsMap))
+}

pkg/maps/eventsmap/eventsmap.go

@@ -11,10 +11,6 @@ import (
 	"github.com/cilium/cilium/pkg/option"
 )
 
-var (
-	MaxEntries int
-)
-
 const (
 	// MapName is the BPF map name.
 	MapName = "cilium_events"
@@ -50,18 +46,21 @@ func (v *Value) String() string { return fmt.Sprintf("%d", v.progID) }
 // map value.
 func (k Key) NewValue() bpf.MapValue { return &Value{} }
 
-// InitMap creates the events map in the kernel.
-func InitMap(maxEntries int) error {
-	MaxEntries = maxEntries
-	eventsMap := bpf.NewMap(MapName,
+type eventsMap struct {
+	m *bpf.Map
+}
+
+// init creates the events map in the kernel.
+func (e *eventsMap) init(maxEntries int) error {
+	e.m = bpf.NewMap(MapName,
 		bpf.MapTypePerfEventArray,
 		&Key{},
 		int(unsafe.Sizeof(Key{})),
 		&Value{},
 		int(unsafe.Sizeof(Value{})),
-		MaxEntries,
+		maxEntries,
 		0,
 		bpf.ConvertKeyValue).
 		WithEvents(option.Config.GetEventBufferConfig(MapName))
-	return eventsMap.Create()
+	return e.m.Create()
 }

pkg/monitor/agent/agent.go

@@ -21,14 +21,13 @@ import (
 	oldBPF "github.com/cilium/cilium/pkg/bpf"
 	"github.com/cilium/cilium/pkg/lock"
 	"github.com/cilium/cilium/pkg/logging/logfields"
+	"github.com/cilium/cilium/pkg/maps/eventsmap"
 	"github.com/cilium/cilium/pkg/monitor/agent/consumer"
 	"github.com/cilium/cilium/pkg/monitor/agent/listener"
 	"github.com/cilium/cilium/pkg/monitor/api"
 	"github.com/cilium/cilium/pkg/monitor/payload"
 )
 
-const eventsMapName = "cilium_events"
-
 // isCtxDone is a utility function that returns true when the context's Done()
 // channel is closed. It is intended to simplify goroutines that need to check
 // this multiple times in their loop.
@@ -99,7 +98,7 @@ func (a *Agent) AttachToEventsMap(nPages int) error {
 	}
 
 	// assert that we can actually connect the monitor
-	path := oldBPF.MapPath(eventsMapName)
+	path := oldBPF.MapPath(eventsmap.MapName)
 	eventsMap, err := ebpf.LoadPinnedMap(path, nil)
 	if err != nil {
 		return err