hubble: add peer module that implements the peer gRPC server interface

This commit adds a new peer module for hubble that implements the peer
gRPC server interface.

This new gRPC service notifies of nodes being added, deleted or
modified. This information is obtained by subscribing to the cilium node
manager via a new datapath.NodeHandler interface implementation
(peer.handler).

This new service will be consumed by hubble proxy in order to connect to
hubble peers. It is intended to only be served over a local unix domain
socket.

Signed-off-by: Robin Hahling <robin.hahling@gw-computing.net>

pkg/hubble/defaults/defaults.go

@@ -0,0 +1,24 @@
+// Copyright 2020 Authors of Cilium
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package defaults
+
+const (
+	// ServerPort is the default port for hubble server when a provided
+	// listen address does not include one.
+	ServerPort = 4244
+
+	// ProxyPort is the default port for hubble's proxy service.
+	ProxyPort = 4245
+)

pkg/hubble/peer/handler.go

@@ -0,0 +1,117 @@
+// Copyright 2020 Authors of Cilium
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package peer
+
+import (
+	"github.com/cilium/cilium/pkg/datapath"
+	"github.com/cilium/cilium/pkg/node/types"
+
+	peerpb "github.com/cilium/cilium/api/v1/peer"
+)
+
+// handler implements the datapath.NodeHandler interface so that it can be
+// subscribed to a node manager and receives update about nodes being
+// added/updated/deleted. Node update information is turned into
+// peerpb.ChangeNotification and sent to the channel C. As this channel is
+// unbuffered, clients must be ready to read from it before subscribing the
+// handler to the node manager.
+// Once not used anymore, Close must be called to free resources.
+type handler struct {
+	stop chan struct{}
+	C    chan *peerpb.ChangeNotification
+}
+
+func newHandler() *handler {
+	return &handler{
+		stop: make(chan struct{}),
+		C:    make(chan *peerpb.ChangeNotification),
+	}
+}
+
+// Ensure that Service implements the NodeHandler interface so that it can be
+// notified of nodes updates by the daemon's node manager.
+var _ datapath.NodeHandler = (*handler)(nil)
+
+// NodeAdd implements datapath.NodeHandler.NodeAdd.
+func (h *handler) NodeAdd(n types.Node) error {
+	select {
+	case h.C <- &peerpb.ChangeNotification{
+		Name:    n.Fullname(),
+		Address: nodeAddress(n),
+		Type:    peerpb.ChangeNotificationType_PEER_ADDED,
+	}:
+	case <-h.stop:
+	}
+	return nil
+}
+
+// NodeUpdate implements datapath.NodeHandler.NodeUpdate.
+func (h *handler) NodeUpdate(o, n types.Node) error {
+	select {
+	case h.C <- &peerpb.ChangeNotification{
+		Name:    n.Fullname(),
+		Address: nodeAddress(n),
+		Type:    peerpb.ChangeNotificationType_PEER_UPDATED,
+	}:
+	case <-h.stop:
+	}
+	return nil
+}
+
+// NodeDelete implements datapath.NodeHandler.NodeDelete.
+func (h *handler) NodeDelete(n types.Node) error {
+	select {
+	case h.C <- &peerpb.ChangeNotification{
+		Name:    n.Fullname(),
+		Address: nodeAddress(n),
+		Type:    peerpb.ChangeNotificationType_PEER_DELETED,
+	}:
+	case <-h.stop:
+	}
+	return nil
+}
+
+// NodeValidateImplementation implements
+// datapath.NodeHandler.NodeValidateImplementation. It is a no-op.
+func (h handler) NodeValidateImplementation(_ types.Node) error {
+	// no-op
+	return nil
+}
+
+// NodeConfigurationChanged implements
+// datapath.NodeHandler.NodeValidateImplementation. It is a no-op.
+func (h handler) NodeConfigurationChanged(_ datapath.LocalNodeConfiguration) error {
+	// no-op
+	return nil
+}
+
+// Close frees handler resources.
+func (h *handler) Close() {
+	close(h.stop)
+}
+
+// nodeAddress returns the node's address. If the node has both IPv4 and IPv6
+// addresses, IPv4 takes priority.
+func nodeAddress(n types.Node) string {
+	addr := n.GetNodeIP(false)
+	if addr.To4() != nil {
+		return addr.String()
+	}
+	addr = n.GetNodeIP(true)
+	if addr == nil {
+		return ""
+	}
+	return addr.String()
+}