AB#2114 Add QEMU metadata API (#237)

* Add QEMU metadata API

* API server is started automatically when using terraform to deploy a QEMU cluster

* Enable QEMU metadata usage for disk-mapper, debugd and the Coordinator

Signed-off-by: Daniel Weiße <dw@edgeless.systems>

hack/qemu-metadata-api/server/server.go

@@ -0,0 +1,138 @@
+package server
+
+import (
+	"encoding/json"
+	"fmt"
+	"net"
+	"net/http"
+	"strings"
+
+	"github.com/edgelesssys/constellation/coordinator/cloudprovider/cloudtypes"
+	"github.com/edgelesssys/constellation/coordinator/role"
+	"github.com/edgelesssys/constellation/hack/qemu-metadata-api/virtwrapper"
+	"github.com/edgelesssys/constellation/internal/logger"
+	"go.uber.org/zap"
+)
+
+type Server struct {
+	log  *logger.Logger
+	virt virConnect
+}
+
+func New(log *logger.Logger, conn virConnect) *Server {
+	return &Server{
+		log:  log,
+		virt: conn,
+	}
+}
+
+func (s *Server) ListenAndServe(port string) error {
+	mux := http.NewServeMux()
+	mux.Handle("/self", http.HandlerFunc(s.listSelf))
+	mux.Handle("/peers", http.HandlerFunc(s.listPeers))
+
+	server := http.Server{
+		Handler: mux,
+	}
+
+	lis, err := net.Listen("tcp", net.JoinHostPort("", port))
+	if err != nil {
+		return err
+	}
+
+	s.log.Infof("Starting QEMU metadata API on %s", lis.Addr())
+	return server.Serve(lis)
+}
+
+// listSelf returns peer information about the instance issuing the request.
+func (s *Server) listSelf(w http.ResponseWriter, r *http.Request) {
+	log := s.log.With(zap.String("peer", r.RemoteAddr))
+	log.Infof("Serving GET request for /self")
+
+	remoteIP, _, err := net.SplitHostPort(r.RemoteAddr)
+	if err != nil {
+		log.With(zap.Error(err)).Errorf("Failed to parse remote address")
+		http.Error(w, fmt.Sprintf("Failed to parse remote address: %s\n", err), http.StatusInternalServerError)
+		return
+	}
+
+	peers, err := s.listAll()
+	if err != nil {
+		log.With(zap.Error(err)).Errorf("Failed to list peer metadata")
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	for _, peer := range peers {
+		for _, ip := range peer.PublicIPs {
+			if ip == remoteIP {
+				w.Header().Set("Content-Type", "application/json")
+				if err := json.NewEncoder(w).Encode(peer); err != nil {
+					http.Error(w, err.Error(), http.StatusInternalServerError)
+					return
+				}
+				log.Infof("Request successful")
+				return
+			}
+		}
+	}
+
+	log.Errorf("Failed to find peer in active leases")
+	http.Error(w, "No matching peer found", http.StatusNotFound)
+}
+
+// listPeers returns a list of all active peers.
+func (s *Server) listPeers(w http.ResponseWriter, r *http.Request) {
+	log := s.log.With(zap.String("peer", r.RemoteAddr))
+	log.Infof("Serving GET request for /peers")
+
+	peers, err := s.listAll()
+	if err != nil {
+		log.With(zap.Error(err)).Errorf("Failed to list peer metadata")
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	w.Header().Set("Content-Type", "application/json")
+	if err := json.NewEncoder(w).Encode(peers); err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	log.Infof("Request successful")
+}
+
+// listAll returns a list of all active peers.
+func (s *Server) listAll() ([]cloudtypes.Instance, error) {
+	net, err := s.virt.LookupNetworkByName("constellation")
+	if err != nil {
+		return nil, err
+	}
+	defer net.Free()
+
+	leases, err := net.GetDHCPLeases()
+	if err != nil {
+		return nil, err
+	}
+	var peers []cloudtypes.Instance
+
+	for _, lease := range leases {
+		instanceRole := role.Node
+		if strings.HasPrefix(lease.Hostname, "control-plane") {
+			instanceRole = role.Coordinator
+		}
+
+		peers = append(peers, cloudtypes.Instance{
+			Name:       lease.Hostname,
+			Role:       instanceRole,
+			PrivateIPs: []string{lease.IPaddr},
+			PublicIPs:  []string{lease.IPaddr},
+			ProviderID: "qemu:///hostname/" + lease.Hostname,
+		})
+	}
+
+	return peers, nil
+}
+
+type virConnect interface {
+	LookupNetworkByName(name string) (*virtwrapper.Network, error)
+}