Do not display empty lines in docker info if the key doesn't exists

Signed-off-by: Victor Vieux <vieux@docker.com>

api/client/commands.go

@@ -473,20 +473,33 @@ func (cli *DockerCli) CmdInfo(args ...string) error {
 	}
 	out.Close()
 
-	fmt.Fprintf(cli.out, "Containers: %d\n", remoteInfo.GetInt("Containers"))
-	fmt.Fprintf(cli.out, "Images: %d\n", remoteInfo.GetInt("Images"))
-	fmt.Fprintf(cli.out, "Storage Driver: %s\n", remoteInfo.Get("Driver"))
-	var driverStatus [][2]string
-	if err := remoteInfo.GetJson("DriverStatus", &driverStatus); err != nil {
-		return err
+	if remoteInfo.Exists("Containers") {
+		fmt.Fprintf(cli.out, "Containers: %d\n", remoteInfo.GetInt("Containers"))
 	}
-	for _, pair := range driverStatus {
-		fmt.Fprintf(cli.out, " %s: %s\n", pair[0], pair[1])
+	if remoteInfo.Exists("Images") {
+		fmt.Fprintf(cli.out, "Images: %d\n", remoteInfo.GetInt("Images"))
+	}
+	if remoteInfo.Exists("Driver") {
+		fmt.Fprintf(cli.out, "Storage Driver: %s\n", remoteInfo.Get("Driver"))
+	}
+	if remoteInfo.Exists("DriverStatus") {
+		var driverStatus [][2]string
+		if err := remoteInfo.GetJson("DriverStatus", &driverStatus); err != nil {
+			return err
+		}
+		for _, pair := range driverStatus {
+			fmt.Fprintf(cli.out, " %s: %s\n", pair[0], pair[1])
+		}
+	}
+	if remoteInfo.Exists("ExecutionDriver") {
+		fmt.Fprintf(cli.out, "Execution Driver: %s\n", remoteInfo.Get("ExecutionDriver"))
+	}
+	if remoteInfo.Exists("KernelVersion") {
+		fmt.Fprintf(cli.out, "Kernel Version: %s\n", remoteInfo.Get("KernelVersion"))
+	}
+	if remoteInfo.Exists("OperatingSystem") {
+		fmt.Fprintf(cli.out, "Operating System: %s\n", remoteInfo.Get("OperatingSystem"))
 	}
-	fmt.Fprintf(cli.out, "Execution Driver: %s\n", remoteInfo.Get("ExecutionDriver"))
-	fmt.Fprintf(cli.out, "Kernel Version: %s\n", remoteInfo.Get("KernelVersion"))
-	fmt.Fprintf(cli.out, "Operating System: %s\n", remoteInfo.Get("OperatingSystem"))
-
 	if remoteInfo.Exists("NCPU") {
 		fmt.Fprintf(cli.out, "CPUs: %d\n", remoteInfo.GetInt("NCPU"))
 	}
@@ -495,12 +508,19 @@ func (cli *DockerCli) CmdInfo(args ...string) error {
 	}
 
 	if remoteInfo.GetBool("Debug") || os.Getenv("DEBUG") != "" {
-		fmt.Fprintf(cli.out, "Debug mode (server): %v\n", remoteInfo.GetBool("Debug"))
+		if remoteInfo.Exists("Debug") {
+			fmt.Fprintf(cli.out, "Debug mode (server): %v\n", remoteInfo.GetBool("Debug"))
+		}
 		fmt.Fprintf(cli.out, "Debug mode (client): %v\n", os.Getenv("DEBUG") != "")
-		fmt.Fprintf(cli.out, "Fds: %d\n", remoteInfo.GetInt("NFd"))
-		fmt.Fprintf(cli.out, "Goroutines: %d\n", remoteInfo.GetInt("NGoroutines"))
-		fmt.Fprintf(cli.out, "EventsListeners: %d\n", remoteInfo.GetInt("NEventsListener"))
-
+		if remoteInfo.Exists("NFd") {
+			fmt.Fprintf(cli.out, "Fds: %d\n", remoteInfo.GetInt("NFd"))
+		}
+		if remoteInfo.Exists("NGoroutines") {
+			fmt.Fprintf(cli.out, "Goroutines: %d\n", remoteInfo.GetInt("NGoroutines"))
+		}
+		if remoteInfo.Exists("NEventsListener") {
+			fmt.Fprintf(cli.out, "EventsListeners: %d\n", remoteInfo.GetInt("NEventsListener"))
+		}
 		if initSha1 := remoteInfo.Get("InitSha1"); initSha1 != "" {
 			fmt.Fprintf(cli.out, "Init SHA1: %s\n", initSha1)
 		}
@@ -517,13 +537,13 @@ func (cli *DockerCli) CmdInfo(args ...string) error {
 			fmt.Fprintf(cli.out, "Registry: %v\n", remoteInfo.GetList("IndexServerAddress"))
 		}
 	}
-	if !remoteInfo.GetBool("MemoryLimit") {
+	if remoteInfo.Exists("MemoryLimit") && !remoteInfo.GetBool("MemoryLimit") {
 		fmt.Fprintf(cli.err, "WARNING: No memory limit support\n")
 	}
-	if !remoteInfo.GetBool("SwapLimit") {
+	if remoteInfo.Exists("SwapLimit") && !remoteInfo.GetBool("SwapLimit") {
 		fmt.Fprintf(cli.err, "WARNING: No swap limit support\n")
 	}
-	if !remoteInfo.GetBool("IPv4Forwarding") {
+	if remoteInfo.Exists("IPv4Forwarding") && !remoteInfo.GetBool("IPv4Forwarding") {
 		fmt.Fprintf(cli.err, "WARNING: IPv4 forwarding is disabled.\n")
 	}
 	return nil