Use warnings provided by daemon

Warnings are now generated by the daemon, and returned as
part of the /info API response.

If warnings are returned by the daemon; use those instead
of generating them locally.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

cli/command/system/info.go

@@ -206,45 +206,7 @@ func prettyPrintInfo(dockerCli command.Cli, info types.Info) error {
 	fmt.Fprintln(dockerCli.Out(), "Live Restore Enabled:", info.LiveRestoreEnabled)
 	fmt.Fprint(dockerCli.Out(), "\n")
 
-	// Only output these warnings if the server does not support these features
-	if info.OSType != "windows" {
-		printStorageDriverWarnings(dockerCli, info)
-
-		if !info.MemoryLimit {
-			fmt.Fprintln(dockerCli.Err(), "WARNING: No memory limit support")
-		}
-		if !info.SwapLimit {
-			fmt.Fprintln(dockerCli.Err(), "WARNING: No swap limit support")
-		}
-		if !info.KernelMemory {
-			fmt.Fprintln(dockerCli.Err(), "WARNING: No kernel memory limit support")
-		}
-		if !info.OomKillDisable {
-			fmt.Fprintln(dockerCli.Err(), "WARNING: No oom kill disable support")
-		}
-		if !info.CPUCfsQuota {
-			fmt.Fprintln(dockerCli.Err(), "WARNING: No cpu cfs quota support")
-		}
-		if !info.CPUCfsPeriod {
-			fmt.Fprintln(dockerCli.Err(), "WARNING: No cpu cfs period support")
-		}
-		if !info.CPUShares {
-			fmt.Fprintln(dockerCli.Err(), "WARNING: No cpu shares support")
-		}
-		if !info.CPUSet {
-			fmt.Fprintln(dockerCli.Err(), "WARNING: No cpuset support")
-		}
-		if !info.IPv4Forwarding {
-			fmt.Fprintln(dockerCli.Err(), "WARNING: IPv4 forwarding is disabled")
-		}
-		if !info.BridgeNfIptables {
-			fmt.Fprintln(dockerCli.Err(), "WARNING: bridge-nf-call-iptables is disabled")
-		}
-		if !info.BridgeNfIP6tables {
-			fmt.Fprintln(dockerCli.Err(), "WARNING: bridge-nf-call-ip6tables is disabled")
-		}
-	}
-
+	printWarnings(dockerCli, info)
 	return nil
 }
 
@@ -305,11 +267,73 @@ func printSwarmInfo(dockerCli command.Cli, info types.Info) {
 	}
 }
 
+func printWarnings(dockerCli command.Cli, info types.Info) {
+	if len(info.Warnings) > 0 {
+		fmt.Fprintln(dockerCli.Err(), strings.Join(info.Warnings, "\n"))
+		return
+	}
+	// daemon didn't return warnings. Fallback to old behavior
+	printStorageDriverWarnings(dockerCli, info)
+	printWarningsLegacy(dockerCli, info)
+}
+
+// printWarningsLegacy generates warnings based on information returned by the daemon.
+// DEPRECATED: warnings are now generated by the daemon, and returned in
+// info.Warnings. This function is used to provide backward compatibility with
+// daemons that do not provide these warnings. No new warnings should be added
+// here.
+func printWarningsLegacy(dockerCli command.Cli, info types.Info) {
+	if info.OSType == "windows" {
+		return
+	}
+	if !info.MemoryLimit {
+		fmt.Fprintln(dockerCli.Err(), "WARNING: No memory limit support")
+	}
+	if !info.SwapLimit {
+		fmt.Fprintln(dockerCli.Err(), "WARNING: No swap limit support")
+	}
+	if !info.KernelMemory {
+		fmt.Fprintln(dockerCli.Err(), "WARNING: No kernel memory limit support")
+	}
+	if !info.OomKillDisable {
+		fmt.Fprintln(dockerCli.Err(), "WARNING: No oom kill disable support")
+	}
+	if !info.CPUCfsQuota {
+		fmt.Fprintln(dockerCli.Err(), "WARNING: No cpu cfs quota support")
+	}
+	if !info.CPUCfsPeriod {
+		fmt.Fprintln(dockerCli.Err(), "WARNING: No cpu cfs period support")
+	}
+	if !info.CPUShares {
+		fmt.Fprintln(dockerCli.Err(), "WARNING: No cpu shares support")
+	}
+	if !info.CPUSet {
+		fmt.Fprintln(dockerCli.Err(), "WARNING: No cpuset support")
+	}
+	if !info.IPv4Forwarding {
+		fmt.Fprintln(dockerCli.Err(), "WARNING: IPv4 forwarding is disabled")
+	}
+	if !info.BridgeNfIptables {
+		fmt.Fprintln(dockerCli.Err(), "WARNING: bridge-nf-call-iptables is disabled")
+	}
+	if !info.BridgeNfIP6tables {
+		fmt.Fprintln(dockerCli.Err(), "WARNING: bridge-nf-call-ip6tables is disabled")
+	}
+}
+
+// printStorageDriverWarnings generates warnings based on storage-driver information
+// returned by the daemon.
+// DEPRECATED: warnings are now generated by the daemon, and returned in
+// info.Warnings. This function is used to provide backward compatibility with
+// daemons that do not provide these warnings. No new warnings should be added
+// here.
 func printStorageDriverWarnings(dockerCli command.Cli, info types.Info) {
+	if info.OSType == "windows" {
+		return
+	}
 	if info.DriverStatus == nil {
 		return
 	}
-
 	for _, pair := range info.DriverStatus {
 		if pair[0] == "Data loop file" {
 			fmt.Fprintf(dockerCli.Err(), "WARNING: %s: usage of loopback devices is "+