EE license fixes. (#5383) (#5384)

( git cherry-pick 4e35cba)
Fixes DGRAPH-1341

This patch make several fixes and improvements
 -  Apply the option enterprise_license only after the node's Raft is initialized and it is the leader.
  - Don't apply the trial license if a license already exists.
  - Disallow the enterprise_license option for OSS build and bail out.
  - Apply the option even if there is a license from a previous life of the Zero (i.e. Zero is restarted with same the zw/

dgraph/cmd/zero/license.go

@@ -22,6 +22,7 @@ import (
 	"net/http"
 
 	"github.com/dgraph-io/badger/v2/y"
+	"github.com/dgraph-io/dgraph/protos/pb"
 )
 
 // dummy function as enterprise features are not available in oss binary.
@@ -38,6 +39,10 @@ func (st *state) applyEnterpriseLicense(w http.ResponseWriter, r *http.Request)
 	w.WriteHeader(http.StatusNotFound)
 }
 
-func (st *state) applyLicenseFile(path string) error {
+func (s *Server) applyLicenseFile(path string) {
+	return
+}
+
+func (s *Server) license() *pb.License {
 	return nil
 }

dgraph/cmd/zero/license_ee.go

@@ -42,7 +42,7 @@ func (n *node) proposeTrialLicense() error {
 		return err
 
 	}
-	glog.Infof("Enterprise state proposed to the cluster: %v", proposal)
+	glog.Infof("Enterprise trial license proposed to the cluster: %v", proposal)
 	return nil
 }
 
@@ -135,14 +135,15 @@ func (st *state) applyEnterpriseLicense(w http.ResponseWriter, r *http.Request)
 	}
 }
 
-// applyLicenseFile applies the license file stored at the given path.
-func (st *state) applyLicenseFile(path string) error {
+func (s *Server) applyLicenseFile(path string) {
 	content, err := ioutil.ReadFile(path)
 	if err != nil {
-		return err
+		glog.Infof("Unable to apply license at %v due to error %v", path, err)
+		return
 	}
-
 	ctx, cancel := context.WithTimeout(context.Background(), time.Minute)
 	defer cancel()
-	return st.zero.applyLicense(ctx, bytes.NewReader(content))
+	if err = s.applyLicense(ctx, bytes.NewReader(content)); err != nil {
+		glog.Infof("Unable to apply license at %v due to error %v", path, err)
+	}
 }

dgraph/cmd/zero/raft.go

@@ -517,8 +517,11 @@ func (n *node) initAndStartNode() error {
 				time.Sleep(3 * time.Second)
 			}
 
-			if err := n.proposeTrialLicense(); err != nil {
-				glog.Errorf("while proposing trial license to cluster: %v", err)
+			// Apply trial license only if not already licensed.
+			if n.server.license() == nil {
+				if err := n.proposeTrialLicense(); err != nil {
+					glog.Errorf("while proposing trial license to cluster: %v", err)
+				}
 			}
 		}()
 	}
@@ -618,6 +621,7 @@ func (n *node) trySnapshot(skip uint64) {
 
 func (n *node) Run() {
 	var leader bool
+	licenseApplied := false
 	ticker := time.NewTicker(100 * time.Millisecond)
 	defer ticker.Stop()
 
@@ -735,6 +739,17 @@ func (n *node) Run() {
 						" Num entries: %d. MustSync: %v",
 					timer.String(), len(rd.Entries), rd.MustSync)
 			}
+
+			// Apply license when I am the leader.
+			if !licenseApplied && n.AmLeader() {
+				licenseApplied = true
+				// Apply the EE License given on CLI which may over-ride previous
+				// license, if present. That is an intended behavior to allow customers
+				// to apply new/renewed licenses.
+				if license := Zero.Conf.GetString("enterprise_license"); len(license) > 0 {
+					go n.server.applyLicenseFile(license)
+				}
+			}
 		}
 	}
 }

dgraph/cmd/zero/run.go

@@ -188,6 +188,10 @@ func run() {
 		LudicrousMode: Zero.Conf.GetBool("ludicrous_mode"),
 	}
 
+	if !enc.EeBuild && Zero.Conf.GetString("enterprise_license") != "" {
+		log.Fatalf("ERROR: enterprise_license option cannot be applied to OSS builds. ")
+	}
+
 	if opts.numReplicas < 0 || opts.numReplicas%2 == 0 {
 		log.Fatalf("ERROR: Number of replicas must be odd for consensus. Found: %d",
 			opts.numReplicas)
@@ -241,14 +245,6 @@ func run() {
 	st.serveGRPC(grpcListener, store)
 	st.serveHTTP(httpListener)
 
-	// Apply enterprise license if one was given.
-	if license := Zero.Conf.GetString("enterprise_license"); len(license) > 0 {
-		if err := st.applyLicenseFile(license); err != nil {
-			glog.Warningf("Applying enterprise license file %s failed with error: %s", license,
-				err.Error())
-		}
-	}
-
 	http.HandleFunc("/health", st.pingResponse)
 	http.HandleFunc("/state", st.getState)
 	http.HandleFunc("/removeNode", st.removeNode)

dgraph/cmd/zero/zero.go

@@ -780,6 +780,6 @@ func (s *Server) applyLicense(ctx context.Context, signedData io.Reader) error {
 	if err != nil {
 		return errors.Wrapf(err, "while proposing enterprise license state to cluster")
 	}
-	glog.Infof("Enterprise license state proposed to the cluster")
+	glog.Infof("Enterprise license proposed to the cluster %+v", proposal)
 	return nil
 }