From 6d0e1c9feaf8c615d173c1e9967c4f357c7a29ef Mon Sep 17 00:00:00 2001
From: Preetha Appan <preetha@hashicorp.com>
Date: Tue, 10 Apr 2018 08:47:33 -0500
Subject: [PATCH] Use preconfigured nodeID if there isn't a persisted node ID,
 and persist it if its not persisted.

---
 command/agent/agent.go | 45 ++++++++++++++++++++++++------------------
 nomad/config.go        |  4 ++--
 nomad/server_test.go   |  1 -
 nomad/testing.go       |  2 --
 4 files changed, 28 insertions(+), 24 deletions(-)

diff --git a/command/agent/agent.go b/command/agent/agent.go
index 8b3c96856..c8fccfd1c 100644
--- a/command/agent/agent.go
+++ b/command/agent/agent.go
@@ -533,26 +533,10 @@ func (a *Agent) setupServer() error {
 // setupNodeID will pull the persisted node ID, if any, or create a random one
 // and persist it.
 func (a *Agent) setupNodeID(config *nomad.Config) error {
-	// If they've configured a node ID manually then just use that, as
-	// long as it's valid.
-	if config.NodeID != "" {
-		config.NodeID = strings.ToLower(string(config.NodeID))
-		if _, err := uuidparse.ParseUUID(string(config.NodeID)); err != nil {
-			return err
-		}
-
-		return nil
-	}
-
-	// For dev mode we have no filesystem access so just make one.
-	if a.config.DevMode {
-		config.NodeID = uuid.Generate()
-		return nil
-	}
-
 	// Load saved state, if any. Since a user could edit this, we also
-	// validate it.
+	// validate it. Saved state overwrites any configured node id
 	fileID := filepath.Join(config.DataDir, "node-id")
+	savedNodeID := false
 	if _, err := os.Stat(fileID); err == nil {
 		rawID, err := ioutil.ReadFile(fileID)
 		if err != nil {
@@ -564,8 +548,31 @@ func (a *Agent) setupNodeID(config *nomad.Config) error {
 		if _, err := uuidparse.ParseUUID(nodeID); err != nil {
 			return err
 		}
-
 		config.NodeID = nodeID
+		savedNodeID = true
+	}
+
+	// If they've configured a node ID manually then just use that, as
+	// long as it's valid.
+	if !savedNodeID && config.NodeID != "" {
+		config.NodeID = strings.ToLower(string(config.NodeID))
+		if _, err := uuidparse.ParseUUID(string(config.NodeID)); err != nil {
+			return err
+		}
+		// Persist this configured nodeID to our data directory
+		if err := lib.EnsurePath(fileID, false); err != nil {
+			return err
+		}
+		if err := ioutil.WriteFile(fileID, []byte(config.NodeID), 0600); err != nil {
+			return err
+		}
+		return nil
+	}
+
+	// For dev mode we have no filesystem access so just make one.
+	if a.config.DevMode {
+		config.NodeID = uuid.Generate()
+		return nil
 	}
 
 	// If we still don't have a valid node ID, make one.
diff --git a/nomad/config.go b/nomad/config.go
index 17dcbed42..12cb9825c 100644
--- a/nomad/config.go
+++ b/nomad/config.go
@@ -10,6 +10,7 @@ import (
 
 	"github.com/hashicorp/memberlist"
 	"github.com/hashicorp/nomad/helper/tlsutil"
+	"github.com/hashicorp/nomad/helper/uuid"
 	"github.com/hashicorp/nomad/nomad/structs"
 	"github.com/hashicorp/nomad/nomad/structs/config"
 	"github.com/hashicorp/nomad/scheduler"
@@ -311,13 +312,12 @@ func DefaultConfig() *Config {
 		panic(err)
 	}
 
-	// TODO Add back random node ID and always persist in the agent startup
-	// TODO Remove places I added uuid.Generate()
 	c := &Config{
 		Region:                           DefaultRegion,
 		AuthoritativeRegion:              DefaultRegion,
 		Datacenter:                       DefaultDC,
 		NodeName:                         hostname,
+		NodeID:                           uuid.Generate(),
 		ProtocolVersion:                  ProtocolVersionMax,
 		RaftConfig:                       raft.DefaultConfig(),
 		RaftTimeout:                      10 * time.Second,
diff --git a/nomad/server_test.go b/nomad/server_test.go
index dd9f2b81b..3bdb58e7e 100644
--- a/nomad/server_test.go
+++ b/nomad/server_test.go
@@ -532,7 +532,6 @@ func TestServer_InvalidSchedulers(t *testing.T) {
 	require := require.New(t)
 
 	config := DefaultConfig()
-	config.NodeID = uuid.Generate()
 	config.DevMode = true
 	config.LogOutput = testlog.NewWriter(t)
 	config.SerfConfig.MemberlistConfig.BindAddr = "127.0.0.1"
diff --git a/nomad/testing.go b/nomad/testing.go
index 9e09e60c7..2859dfb63 100644
--- a/nomad/testing.go
+++ b/nomad/testing.go
@@ -11,7 +11,6 @@ import (
 	"github.com/hashicorp/consul/lib/freeport"
 	"github.com/hashicorp/nomad/command/agent/consul"
 	"github.com/hashicorp/nomad/helper/testlog"
-	"github.com/hashicorp/nomad/helper/uuid"
 	"github.com/hashicorp/nomad/nomad/mock"
 	"github.com/hashicorp/nomad/nomad/structs"
 	"github.com/mitchellh/go-testing-interface"
@@ -39,7 +38,6 @@ func TestACLServer(t testing.T, cb func(*Config)) (*Server, *structs.ACLToken) {
 func TestServer(t testing.T, cb func(*Config)) *Server {
 	// Setup the default settings
 	config := DefaultConfig()
-	config.NodeID = uuid.Generate()
 	config.Build = "0.8.0+unittest"
 	config.DevMode = true
 	nodeNum := atomic.AddUint32(&nodeNumber, 1)