ctr: fix potential panic in metric

Ace-Tang · Ace-Tang · commit c3cac72b92a5 · 2018-10-23T14:01:50.000+08:00
Signed-off-by: Ace-Tang &lt;aceapril@126.com&gt;
diff --git a/cmd/ctr/commands/tasks/metrics.go b/cmd/ctr/commands/tasks/metrics.go
@@ -89,13 +89,19 @@ var metricsCommand = cli.Command{
 			fmt.Fprintf(w, "%s\t%s\t\n\n", metric.ID, metric.Timestamp)
 
 			fmt.Fprintf(w, "METRIC\tVALUE\t\n")
-			fmt.Fprintf(w, "memory.usage_in_bytes\t%d\t\n", data.Memory.Usage.Usage)
-			fmt.Fprintf(w, "memory.limit_in_bytes\t%d\t\n", data.Memory.Usage.Limit)
-			fmt.Fprintf(w, "memory.stat.cache\t%d\t\n", data.Memory.TotalCache)
-			fmt.Fprintf(w, "cpuacct.usage\t%d\t\n", data.CPU.Usage.Total)
-			fmt.Fprintf(w, "cpuacct.usage_percpu\t%v\t\n", data.CPU.Usage.PerCPU)
-			fmt.Fprintf(w, "pids.current\t%v\t\n", data.Pids.Current)
-			fmt.Fprintf(w, "pids.limit\t%v\t\n", data.Pids.Limit)
+			if data.Memory != nil {
+				fmt.Fprintf(w, "memory.usage_in_bytes\t%d\t\n", data.Memory.Usage.Usage)
+				fmt.Fprintf(w, "memory.limit_in_bytes\t%d\t\n", data.Memory.Usage.Limit)
+				fmt.Fprintf(w, "memory.stat.cache\t%d\t\n", data.Memory.TotalCache)
+			}
+			if data.CPU != nil {
+				fmt.Fprintf(w, "cpuacct.usage\t%d\t\n", data.CPU.Usage.Total)
+				fmt.Fprintf(w, "cpuacct.usage_percpu\t%v\t\n", data.CPU.Usage.PerCPU)
+			}
+			if data.Pids != nil {
+				fmt.Fprintf(w, "pids.current\t%v\t\n", data.Pids.Current)
+				fmt.Fprintf(w, "pids.limit\t%v\t\n", data.Pids.Limit)
+			}
 			return w.Flush()
 		case formatJSON:
 			marshaledJSON, err := json.MarshalIndent(data, "", "  ")
