collect disk usage on rootfs for maintenance report

misc/sys.go

@@ -78,6 +78,19 @@ func GetSystemUptimeSec() int {
 	return FindNumInRegexGroup(RegexTotalUptimeSec, string(content), 1)
 }
 
+// GetRootDiskUsageKB returns used and total space of the file system mounted on /. Returns 0 if they cannot be determined.
+func GetRootDiskUsageKB() (usedKB, freeKB, totalKB int) {
+	fs := syscall.Statfs_t{}
+	err := syscall.Statfs("/", &fs)
+	if err != nil {
+		return
+	}
+	totalKB = int(int64(fs.Blocks) * fs.Bsize / 1024)
+	freeKB = int(int64(fs.Bfree) * fs.Bsize / 1024)
+	usedKB = totalKB - freeKB
+	return
+}
+
 /*
 UtilityDir is an element of PATH that points to a directory where laitos bundled utility programs are stored. The
 utility programs are not essential to most of laitos operations, however they come in handy in certain scenarios:

misc/sys_test.go

@@ -56,6 +56,14 @@ func TestGetSystemUptimeSec(t *testing.T) {
 	}
 }
 
+func TestGetRootDiskUsageKB(t *testing.T) {
+	SkipTestIfCI(t)
+	used, free, total := GetRootDiskUsageKB()
+	if used == 0 || free == 0 || total == 0 || used+free != total {
+		t.Fatal(used/1024, free/1024, total/1024)
+	}
+}
+
 func TestGetSysctl(t *testing.T) {
 	key := "kernel.pid_max"
 	if runtime.GOOS != "linux" {

toolbox/env_control.go

@@ -67,10 +67,12 @@ func (info *EnvControl) Execute(cmd Command) *Result {
 // Return runtime information (uptime, CPUs, goroutines, memory usage) in a multi-line text.
 func GetRuntimeInfo() string {
 	usedMem, totalMem := misc.GetSystemMemoryUsageKB()
+	usedRoot, freeRoot, totalRoot := misc.GetRootDiskUsageKB()
 	return fmt.Sprintf(`IP: %s
 Clock: %s
 Sys/prog uptime: %s / %s
 Total/used/prog mem: %d / %d / %d MB
+Total/used/free rootfs: %d / %d / %d MB
 Sys load: %s
 Num CPU/GOMAXPROCS/goroutines: %d / %d / %d
 Program flags: %v
@@ -79,6 +81,7 @@ Program flags: %v
 		time.Now().String(),
 		time.Duration(misc.GetSystemUptimeSec()*int(time.Second)).String(), time.Now().Sub(misc.StartupTime).String(),
 		totalMem/1024, usedMem/1024, misc.GetProgramMemoryUsageKB()/1024,
+		totalRoot/1024, usedRoot/1024, freeRoot/1024,
 		misc.GetSystemLoad(),
 		runtime.NumCPU(), runtime.GOMAXPROCS(0), runtime.NumGoroutine(),
 		os.Args[1:])