Fix no_host_uuid parsing

Need to pointerify it to default to true since we can't tell false from
unset if it's not a pointer.

command/agent/agent.go

@@ -322,7 +322,12 @@ func (a *Agent) clientConfig() (*clientconfig.Config, error) {
 	conf.GCDiskUsageThreshold = a.config.Client.GCDiskUsageThreshold
 	conf.GCInodeUsageThreshold = a.config.Client.GCInodeUsageThreshold
 	conf.GCMaxAllocs = a.config.Client.GCMaxAllocs
-	conf.NoHostUUID = a.config.Client.NoHostUUID
+	if a.config.Client.NoHostUUID != nil {
+		conf.NoHostUUID = *a.config.Client.NoHostUUID
+	} else {
+		// Default no_host_uuid to true
+		conf.NoHostUUID = true
+	}
 
 	return conf, nil
 }

command/agent/config.go

@@ -226,7 +226,7 @@ type ClientConfig struct {
 
 	// NoHostUUID disables using the host's UUID and will force generation of a
 	// random UUID.
-	NoHostUUID bool `mapstructure:"no_host_uuid"`
+	NoHostUUID *bool `mapstructure:"no_host_uuid"`
 }
 
 // ServerConfig is configuration specific to the server mode
@@ -543,7 +543,7 @@ func DefaultConfig() *Config {
 			GCDiskUsageThreshold:  80,
 			GCInodeUsageThreshold: 70,
 			GCMaxAllocs:           50,
-			NoHostUUID:            true,
+			NoHostUUID:            helper.BoolToPtr(true),
 		},
 		Server: &ServerConfig{
 			Enabled:          false,
@@ -1005,7 +1005,7 @@ func (a *ClientConfig) Merge(b *ClientConfig) *ClientConfig {
 		result.GCMaxAllocs = b.GCMaxAllocs
 	}
 	// NoHostUUID defaults to true, merge if false
-	if !b.NoHostUUID {
+	if b.NoHostUUID != nil {
 		result.NoHostUUID = b.NoHostUUID
 	}
 

command/agent/config_parse_test.go

@@ -7,6 +7,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/hashicorp/nomad/helper"
 	"github.com/hashicorp/nomad/nomad/structs/config"
 	"github.com/kr/pretty"
 )
@@ -78,7 +79,7 @@ func TestConfig_Parse(t *testing.T) {
 					GCDiskUsageThreshold:  82,
 					GCInodeUsageThreshold: 91,
 					GCMaxAllocs:           50,
-					NoHostUUID:            false,
+					NoHostUUID:            helper.BoolToPtr(false),
 				},
 				Server: &ServerConfig{
 					Enabled:           true,