feat: capture filesystems

cmd/root.go

@@ -86,7 +86,8 @@ func init() {
 
 	// Options for optional ephemeral system properties.
 	f.BoolVarP(&scanner.Swap, "swap", "s", false, "capture swap entries")
-	f.BoolVarP(&scanner.Ephemeral, "ephemeral", "e", false, "capture all ephemeral properties e.g. swap, filesystems and so on")
+	f.BoolVarP(&scanner.Mounts, "mounts", "m", false, "capture filesystem mounts")
+	f.BoolVarP(&scanner.Ephemeral, "ephemeral", "e", false, "capture all ephemeral properties e.g. swap, mounts and so on")
 
 	// We currently support all probe features at a high level as they share some generic information,
 	// but we do not have mappings for all of their detail sections.

go.mod

@@ -23,6 +23,7 @@ require (
 	github.com/mattn/go-isatty v0.0.18 // indirect
 	github.com/mattn/go-runewidth v0.0.15 // indirect
 	github.com/mitchellh/mapstructure v1.5.0 // indirect
+	github.com/moby/sys/mountinfo v0.7.2 // indirect
 	github.com/muesli/reflow v0.3.0 // indirect
 	github.com/muesli/termenv v0.15.2 // indirect
 	github.com/pelletier/go-toml/v2 v2.2.2 // indirect

go.sum

@@ -38,6 +38,8 @@ github.com/mattn/go-runewidth v0.0.15 h1:UNAjwbU9l54TA3KzvqLGxwWjHmMgBUVhBiTjelZ
 github.com/mattn/go-runewidth v0.0.15/go.mod h1:Jdepj2loyihRzMpdS35Xk/zdY8IAYHsh153qUoGf23w=
 github.com/mitchellh/mapstructure v1.5.0 h1:jeMsZIYE/09sWLaz43PL7Gy6RuMjD2eJVyuac5Z2hdY=
 github.com/mitchellh/mapstructure v1.5.0/go.mod h1:bFUtVrKA4DC2yAKiSyO/QUcy7e+RRV2QTWOzhPopBRo=
+github.com/moby/sys/mountinfo v0.7.2 h1:1shs6aH5s4o5H2zQLn796ADW1wMrIwHsyJ2v9KouLrg=
+github.com/moby/sys/mountinfo v0.7.2/go.mod h1:1YOa8w8Ih7uW0wALDUgT1dTTSBrZ+HiBLGws92L2RU4=
 github.com/muesli/reflow v0.3.0 h1:IFsN6K9NfGtjeggFP+68I4chLZV2yIKsXJFNZ+eWh6s=
 github.com/muesli/reflow v0.3.0/go.mod h1:pbwTDkVPibjO2kyvBQRBxTWEEGDGq0FlB1BIKtnHY/8=
 github.com/muesli/termenv v0.15.2 h1:GohcuySI0QmI3wN8Ok9PtKGkgkFIk7y6Vpb5PvrY+Wo=

nix/packages/nixos-facter/gomod2nix.toml

@@ -43,6 +43,9 @@ schema = 3
   [mod."github.com/mitchellh/mapstructure"]
     version = "v1.5.0"
     hash = "sha256-ztVhGQXs67MF8UadVvG72G3ly0ypQW0IRDdOOkjYwoE="
+  [mod."github.com/moby/sys/mountinfo"]
+    version = "v0.7.2"
+    hash = "sha256-G0K/wHnhvJ+00gjjtvScvnttQYxPaDru5HniwBM0+vA="
   [mod."github.com/muesli/reflow"]
     version = "v0.3.0"
     hash = "sha256-Pou2ybE9SFSZG6YfZLVV1Eyfm+X4FuVpDPLxhpn47Cc="

pkg/ephem/fs.go

@@ -0,0 +1,60 @@
+package ephem
+
+import (
+	"encoding/json"
+	"regexp"
+	"strconv"
+	"strings"
+
+	"github.com/moby/sys/mountinfo"
+)
+
+var specialFsRegex = regexp.MustCompile(`^(/proc|/dev|/sys|/run|/var/lib/docker|/var/lib/nfs/rpc_pipefs).*`)
+
+// MountInfo represents the information about a mount point.
+// It is just a type alias for mountinfo.Info to allow us to add JSON marshalling.
+type MountInfo struct {
+	mountinfo.Info
+}
+
+func (i MountInfo) MarshalJSON() ([]byte, error) {
+	return json.Marshal(map[string]string{
+		"id":              strconv.Itoa(i.ID),
+		"parent_id":       strconv.Itoa(i.Parent),
+		"major":           strconv.Itoa(i.Major),
+		"minor":           strconv.Itoa(i.Minor),
+		"root":            i.Root,
+		"mount_point":     i.Mountpoint,
+		"mount_options":   i.Options,
+		"optional":        i.Optional,
+		"filesystem_type": i.FSType,
+		"mount_source":    i.Source,
+		"super_options":   i.VFSOptions,
+	})
+}
+
+func Mounts() ([]*MountInfo, error) {
+	info, err := mountinfo.GetMounts(mountFilter)
+	if err != nil {
+		return nil, err
+	}
+	var result []*MountInfo
+	for idx := range info {
+		result = append(result, &MountInfo{Info: *info[idx]})
+	}
+	return result, nil
+}
+
+func mountFilter(info *mountinfo.Info) (skip, stop bool) {
+	if skip = specialFsRegex.MatchString(info.Mountpoint); skip {
+		return true, false
+	}
+
+	// skip the read-only bind-mount on /nix/store
+	// https://github.com/NixOS/nixpkgs/blob/dac9cdf8c930c0af98a63cbfe8005546ba0125fb/nixos/modules/installer/tools/nixos-generate-config.pl#L395
+	if info.Mountpoint == "/nix/store" && strings.Contains(info.VFSOptions, "rw") && strings.Contains(info.Options, "ro") {
+		return true, false
+	}
+
+	return false, false
+}

pkg/facter/report.go

@@ -12,6 +12,7 @@ import (
 
 type Report struct {
 	Hardware       []*hwinfo.HardwareItem `json:"hardware"`
+	Mounts         []*ephem.MountInfo     `json:"mounts,omitempty"`
 	Smbios         []hwinfo.Smbios        `json:"smbios,omitempty"`
 	Swap           []*ephem.SwapEntry     `json:"swap,omitempty"`
 	System         string                 `json:"system"`
@@ -20,6 +21,7 @@ type Report struct {
 
 type Scanner struct {
 	Swap      bool
+	Mounts    bool
 	Ephemeral bool
 	Features  []hwinfo.ProbeFeature
 }
@@ -48,5 +50,11 @@ func (s *Scanner) Scan() (*Report, error) {
 		}
 	}
 
+	if s.Ephemeral || s.Mounts {
+		if report.Mounts, err = ephem.Mounts(); err != nil {
+			return nil, fmt.Errorf("failed to detect mounts: %w", err)
+		}
+	}
+
 	return &report, nil
 }