Add node_filesystem_mount_info metric (#2970)

* Add node_filesystem_mount_info metric

Fixes: #1384

---------

Signed-off-by: Miguel Oliveira <miguel.oliveira4224@gmail.com>

collector/filesystem_common.go

@@ -69,11 +69,12 @@ type filesystemCollector struct {
 	sizeDesc, freeDesc, availDesc *prometheus.Desc
 	filesDesc, filesFreeDesc      *prometheus.Desc
 	roDesc, deviceErrorDesc       *prometheus.Desc
+	mountInfoDesc                 *prometheus.Desc
 	logger                        log.Logger
 }
 
 type filesystemLabels struct {
-	device, mountPoint, fsType, options, deviceError string
+	device, mountPoint, fsType, options, deviceError, major, minor string
 }
 
 type filesystemStats struct {
@@ -155,6 +156,13 @@ func NewFilesystemCollector(logger log.Logger) (Collector, error) {
 		filesystemLabelNames, nil,
 	)
 
+	mountInfoDesc := prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, subsystem, "mount_info"),
+		"Filesystem mount information.",
+		[]string{"device", "major", "minor", "mountpoint"},
+		nil,
+	)
+
 	return &filesystemCollector{
 		excludedMountPointsPattern: mountPointPattern,
 		excludedFSTypesPattern:     filesystemsTypesPattern,
@@ -165,6 +173,7 @@ func NewFilesystemCollector(logger log.Logger) (Collector, error) {
 		filesFreeDesc:              filesFreeDesc,
 		roDesc:                     roDesc,
 		deviceErrorDesc:            deviceErrorDesc,
+		mountInfoDesc:              mountInfoDesc,
 		logger:                     logger,
 	}, nil
 }
@@ -215,6 +224,10 @@ func (c *filesystemCollector) Update(ch chan<- prometheus.Metric) error {
 			c.filesFreeDesc, prometheus.GaugeValue,
 			s.filesFree, s.labels.device, s.labels.mountPoint, s.labels.fsType, s.labels.deviceError,
 		)
+		ch <- prometheus.MustNewConstMetric(
+			c.mountInfoDesc, prometheus.GaugeValue,
+			1.0, s.labels.device, s.labels.major, s.labels.minor, s.labels.mountPoint,
+		)
 	}
 	return nil
 }

collector/filesystem_linux.go

@@ -178,11 +178,11 @@ func stuckMountWatcher(mountPoint string, success chan struct{}, logger log.Logg
 }
 
 func mountPointDetails(logger log.Logger) ([]filesystemLabels, error) {
-	file, err := os.Open(procFilePath("1/mounts"))
+	file, err := os.Open(procFilePath("1/mountinfo"))
 	if errors.Is(err, os.ErrNotExist) {
-		// Fallback to `/proc/mounts` if `/proc/1/mounts` is missing due hidepid.
-		level.Debug(logger).Log("msg", "Reading root mounts failed, falling back to system mounts", "err", err)
-		file, err = os.Open(procFilePath("mounts"))
+		// Fallback to `/proc/self/mountinfo` if `/proc/1/mountinfo` is missing due hidepid.
+		level.Debug(logger).Log("msg", "Reading root mounts failed, falling back to self mounts", "err", err)
+		file, err = os.Open(procFilePath("self/mountinfo"))
 	}
 	if err != nil {
 		return nil, err
@@ -199,20 +199,33 @@ func parseFilesystemLabels(r io.Reader) ([]filesystemLabels, error) {
 	for scanner.Scan() {
 		parts := strings.Fields(scanner.Text())
 
-		if len(parts) < 4 {
+		if len(parts) < 10 {
 			return nil, fmt.Errorf("malformed mount point information: %q", scanner.Text())
 		}
 
+		major, minor := 0, 0
+		_, err := fmt.Sscanf(parts[2], "%d:%d", &major, &minor)
+		if err != nil {
+			return nil, fmt.Errorf("malformed mount point information: %q", scanner.Text())
+		}
+
+		m := 5
+		for parts[m+1] != "-" {
+			m++
+		}
+
 		// Ensure we handle the translation of \040 and \011
 		// as per fstab(5).
-		parts[1] = strings.Replace(parts[1], "\\040", " ", -1)
-		parts[1] = strings.Replace(parts[1], "\\011", "\t", -1)
+		parts[4] = strings.Replace(parts[4], "\\040", " ", -1)
+		parts[4] = strings.Replace(parts[4], "\\011", "\t", -1)
 
 		filesystems = append(filesystems, filesystemLabels{
-			device:      parts[0],
-			mountPoint:  rootfsStripPrefix(parts[1]),
-			fsType:      parts[2],
-			options:     parts[3],
+			device:      parts[m+3],
+			mountPoint:  rootfsStripPrefix(parts[4]),
+			fsType:      parts[m+2],
+			options:     parts[5],
+			major:       fmt.Sprint(major),
+			minor:       fmt.Sprint(minor),
 			deviceError: "",
 		})
 	}

collector/filesystem_linux_test.go

@@ -87,10 +87,18 @@ func TestMountPointDetails(t *testing.T) {
 		t.Log(err)
 	}
 
+	foundSet := map[string]bool{}
 	for _, fs := range filesystems {
 		if _, ok := expected[fs.mountPoint]; !ok {
 			t.Errorf("Got unexpected %s", fs.mountPoint)
 		}
+		foundSet[fs.mountPoint] = true
+	}
+
+	for mountPoint := range expected {
+		if _, ok := foundSet[mountPoint]; !ok {
+			t.Errorf("Expected %s, got nothing", mountPoint)
+		}
 	}
 }
 

collector/fixtures/proc/1/mountinfo

@@ -0,0 +1,31 @@
+24 29 0:22 / /sys rw,nosuid,nodev,noexec,relatime shared:7 - sysfs sysfs rw
+25 29 0:23 / /proc rw,nosuid,nodev,noexec,relatime shared:13 - proc proc rw
+26 29 0:5 / /dev rw,nosuid,relatime shared:2 - devtmpfs udev rw,size=7978892k,nr_inodes=1994723,mode=755
+27 26 0:24 / /dev/pts rw,nosuid,noexec,relatime shared:3 - devpts devpts rw,gid=5,mode=620,ptmxmode=000
+28 29 0:25 / /run rw,nosuid,relatime shared:5 - tmpfs tmpfs rw,size=1617716k,mode=755
+29 1 259:2 / / rw,relatime shared:1 - ext4 /dev/dm-2 errors=remount-ro,data=ordered
+30 24 0:6 / /sys/kernel/security rw,nosuid,nodev,noexec,relatime shared:8 - securityfs securityfs rw
+31 26 0:26 / /dev/shm rw,nosuid,nodev shared:4 - tmpfs tmpfs rw,inode64
+32 28 0:27 / /run/lock rw,nosuid,nodev,noexec,relatime shared:6 - tmpfs tmpfs rw,size=5120k
+33 24 0:28 / /sys/fs/cgroup ro,nosuid,nodev,noexec shared:9 - tmpfs tmpfs ro,mode=755
+34 31 0:24 / /sys/fs/cgroup/systemd rw,nosuid,nodev,noexec,relatime shared:10 - cgroup cgroup rw,xattr,release_agent=/lib/systemd/systemd-cgroups-agent,name=systemd
+35 32 0:25 / /sys/fs/pstore rw,nosuid,nodev,noexec,relatime shared:11 - pstore pstore rw
+36 33 0:26 / /sys/fs/cgroup/cpuset rw,nosuid,nodev,noexec,relatime shared:12 - cgroup cgroup rw,cpuset
+37 34 0:27 / /sys/fs/cgroup/cpu,cpuacct rw,nosuid,nodev,noexec,relatime shared:14 - cgroup cgroup rw,cpu,cpuacct
+38 35 0:28 / /sys/fs/cgroup/devices rw,nosuid,nodev,noexec,relatime shared:16 - cgroup cgroup rw,devices
+39 36 0:29 / /sys/fs/cgroup/freezer rw,nosuid,nodev,noexec,relatime shared:17 - cgroup cgroup rw,freezer
+40 37 0:30 / /sys/fs/cgroup/net_cls,net_prio rw,nosuid,nodev,noexec,relatime shared:18 - cgroup cgroup rw,net_cls,net_prio
+41 38 0:31 / /sys/fs/cgroup/blkio rw,nosuid,nodev,noexec,relatime shared:19 - cgroup cgroup rw,blkio
+42 39 0:32 / /sys/fs/cgroup/perf_event rw,nosuid,nodev,noexec,relatime shared:20 - cgroup cgroup rw,perf_event
+43 40 0:33 / /proc/sys/fs/binfmt_misc rw,relatime shared:21 - systemd-1 autofs rw,fd=22,pgrp=1,timeout=300,minproto=5,maxproto=5,direct
+44 41 0:34 / /dev/mqueue rw,relatime shared:22 - mqueue mqueue rw
+45 42 0:35 / /sys/kernel/debug rw,relatime shared:23 - debugfs debugfs rw
+46 43 0:36 / /dev/hugepages rw,relatime shared:24 - hugetlbfs hugetlbfs rw
+47 44 0:37 / /sys/fs/fuse/connections rw,relatime shared:25 - fusectl fusectl rw
+48 45 260:3 / /boot rw,relatime shared:92 - ext2 /dev/sda3 rw
+49 46 0:39 / /run/rpc_pipefs rw,relatime shared:27 - rpc_pipefs rpc_pipefs rw
+265 37 0:41 / /proc/sys/fs/binfmt_misc rw,nosuid,nodev,noexec,relatime shared:94 - binfmt_misc binfmt_misc rw
+3002 28 0:79 / /run/user/1000 rw,nosuid,nodev,relatime shared:1225 - tmpfs tmpfs rw,size=1603436k,nr_inodes=400859,mode=700,uid=1000,gid=1000
+3147 3002 0:81 / /run/user/1000/gvfs rw,nosuid,nodev,relatime shared:1290 - fuse.gvfsd-fuse gvfsd-fuse rw,user_id=1000,group_id=1000
+3148 3003 260:0 / /var/lib/kubelet/plugins/kubernetes.io/vsphere-volume/mounts/[vsanDatastore]\040bafb9e5a-8856-7e6c-699c-801844e77a4a/kubernetes-dynamic-pvc-3eba5bba-48a3-11e8-89ab-005056b92113.vmdk rw,relatime shared:31 - ext4 /dev/sda rw,data=ordered
+3149 3004 260:0 / /var/lib/kubelet/plugins/kubernetes.io/vsphere-volume/mounts/[vsanDatastore]\011bafb9e5a-8856-7e6c-699c-801844e77a4a/kubernetes-dynamic-pvc-3eba5bba-48a3-11e8-89ab-005056b92113.vmdk rw,relatime shared:32 - ext4 /dev/sda rw,data=ordered

collector/fixtures_bindmount/proc/1/mountinfo

@@ -0,0 +1,6 @@
+29 1 259:0 / /host rw,seclabel,relatime,data=ordered shared:1 - ext4 /dev/nvme1n0 rw
+30 1 260:0 / /host/media/volume1 rw,seclabel,relatime,data=ordered shared:1 - ext4 /dev/nvme1n1 rw
+31 1 261:0 / /host/media/volume2 rw,seclabel,relatime,data=ordered shared:1 - ext4 /dev/nvme1n2 rw
+31 26 0:26 / /dev/shm rw,nosuid,nodev shared:4 - tmpfs tmpfs rw,inode64
+32 28 0:27 / /run/lock rw,nosuid,nodev,noexec,relatime shared:6 - tmpfs tmpfs rw,size=5120k,inode64
+33 24 0:28 / /sys/fs/cgroup rw,nosuid,nodev,noexec,relatime shared:9 - cgroup2 cgroup2 rw

collector/fixtures_hidepid/proc/self/mountinfo

@@ -0,0 +1 @@
+29 1 259:2 / / rw,relatime shared:1 - ext4 /dev/nvme0n1p2 rw,errors=remount-ro