test: Initial support for virtiofs mounts (#21272)

* test: Add findmnt package

When testing mounts we can use findmnt --json output to parse the output
cleanly. The package provides only ParseOutput() now, but it can be
extended later to run the findmnt command.

* test: Support virtiofs mounts

Use findmnt command to get the mounted filesystem details cleanly.

We use the actual mount fstype instead of driver name check so we can
switch drivers to virtiofs without changing the test.

For virtiofs mount we skip options validation since we don't support
setting virtiofs options yet, and the options are not the same as 9p
options.

For 9p mounts the uid= and gid= flags were fixed to match the real flags
(dfltuid=,dfltgid=). The issue was hidden by imprecise string matching.

Author: nirs

pkg/minikube/constants/constants.go

@@ -161,6 +161,11 @@ const (
 	// MountUIDFlag is the flag used to set the mount UID
 	MountUIDFlag = "uid"
 
+	// FSType9p is 9p filesystem type
+	FSType9p = "9p"
+	// FSTypeVirtiofs is virtiofs filesystem type
+	FSTypeVirtiofs = "virtiofs"
+
 	// Mirror CN
 	AliyunMirror = "registry.cn-hangzhou.aliyuncs.com/google_containers"
 )

test/integration/findmnt/findmnt.go

@@ -0,0 +1,88 @@
+//go:build integration
+
+/*
+Copyright 2025 The Kubernetes Authors All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+// package parse findmnt command results.
+package findmnt
+
+import (
+	"encoding/json"
+	"slices"
+)
+
+// Filesystem is a findmnt --json filesystem node. It may include children
+// filesystems.
+type Filesystem struct {
+	Target   string       `json:"target"`
+	Source   string       `json:"source"`
+	FSType   string       `json:"fstype"`
+	Options  string       `json:"options"`
+	Children []Filesystem `json:"children,omitempty"`
+}
+
+// Result if findmnt --json result.
+type Result struct {
+	Filesystems []Filesystem `json:"filesystems"`
+}
+
+// ParseOutput parse findmnt --json output.
+func ParseOutput(output []byte) (*Result, error) {
+	r := &Result{}
+	if err := json.Unmarshal(output, r); err != nil {
+		return nil, err
+	}
+	return r, nil
+}
+
+func (r *Result) Equal(other *Result) bool {
+	if r == other {
+		return true
+	}
+	if other == nil {
+		return false
+	}
+	if !slices.EqualFunc(r.Filesystems, other.Filesystems, func(a, b Filesystem) bool {
+		return a.Equal(&b)
+	}) {
+		return false
+	}
+	return true
+}
+
+func (f *Filesystem) Equal(other *Filesystem) bool {
+	if f == other {
+		return true
+	}
+	if other == nil {
+		return false
+	}
+	if f.Target != other.Target {
+		return false
+	}
+	if f.Source != other.Source {
+		return false
+	}
+	if f.FSType != other.FSType {
+		return false
+	}
+	if !slices.EqualFunc(f.Children, other.Children, func(a, b Filesystem) bool {
+		return a.Equal(&b)
+	}) {
+		return false
+	}
+	return true
+}

test/integration/findmnt/findmnt_test.go

@@ -0,0 +1,91 @@
+//go:build integration
+
+/*
+Copyright 2025 The Kubernetes Authors All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package findmnt_test
+
+import (
+	"os"
+	"testing"
+
+	"k8s.io/minikube/test/integration/findmnt"
+)
+
+func TestParseAllMounts(t *testing.T) {
+	// Output from `findmnt --json` command.
+	output, err := os.ReadFile("testdata/findmnt.json")
+	if err != nil {
+		t.Fatal(err)
+	}
+	result, err := findmnt.ParseOutput(output)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	assert(t, len(result.Filesystems), 1)
+
+	root := result.Filesystems[0]
+	assert(t, root.Target, "/")
+	assert(t, root.Source, "tmpfs")
+	assert(t, root.FSType, "tmpfs")
+	assert(t, root.Options, "rw,relatime,size=5469192k")
+	assert(t, len(root.Children), 20)
+
+	dev := root.Children[0]
+	assert(t, dev.Target, "/dev")
+	assert(t, dev.Source, "devtmpfs")
+	assert(t, dev.FSType, "devtmpfs")
+	assert(t, dev.Options, "rw,relatime,size=2838500k,nr_inodes=709625,mode=755")
+	assert(t, len(dev.Children), 4)
+
+	devShm := dev.Children[0]
+	assert(t, devShm.Target, "/dev/shm")
+	assert(t, devShm.Source, "tmpfs")
+	assert(t, devShm.FSType, "tmpfs")
+	assert(t, devShm.Options, "rw,nosuid,nodev")
+}
+
+func TestParseSingle(t *testing.T) {
+	// Output from `findmnt --json /proc` command.
+	output, err := os.ReadFile("testdata/findmnt-proc.json")
+	if err != nil {
+		t.Fatal(err)
+	}
+	result, err := findmnt.ParseOutput(output)
+	if err != nil {
+		t.Fatal(err)
+	}
+	expected := &findmnt.Result{
+		Filesystems: []findmnt.Filesystem{
+			{
+				Target:  "/proc",
+				Source:  "proc",
+				FSType:  "proc",
+				Options: "rw,relatime",
+			},
+		},
+	}
+	if !result.Equal(expected) {
+		t.Fatalf("expected %+v, got %+v", expected, result)
+	}
+}
+
+func assert[T comparable](t *testing.T, a, b T) {
+	if a != b {
+		t.Fatalf("expected \"%v\", got \"%v\"", b, a)
+	}
+}

test/integration/findmnt/testdata/findmnt-proc.json

@@ -0,0 +1,10 @@
+{
+   "filesystems": [
+      {
+         "target": "/proc",
+         "source": "proc",
+         "fstype": "proc",
+         "options": "rw,relatime"
+      }
+   ]
+}