new file mode 100644

@@ -0,0 +1,111 @@

+package container

+

+import (

+	"context"

+	"io"

+	"strings"

+	"testing"

+

+	"github.com/docker/docker/api/types"

+	"github.com/docker/docker/integration/internal/container"

+	"github.com/docker/docker/pkg/archive"

+	"github.com/docker/docker/pkg/dmesg"

+	"gotest.tools/v3/assert"

+	"gotest.tools/v3/skip"

+)

+

+func TestNoOverlayfsWarningsAboutUndefinedBehaviors(t *testing.T) {

+	skip.If(t, testEnv.DaemonInfo.OSType != "linux", "overlayfs is only available on linux")

+	skip.If(t, testEnv.IsRemoteDaemon(), "local daemon is needed for kernel log access")

+	skip.If(t, testEnv.IsRootless(), "root is needed for reading kernel log")

+

+	defer setupTest(t)()

+	client := testEnv.APIClient()

+	ctx := context.Background()

+

+	cID := container.Run(ctx, t, client, container.WithCmd("sh", "-c", `while true; do echo $RANDOM >>/file; sleep 0.1; done`))

+

+	testCases := []struct {

+		name      string

+		operation func(t *testing.T) error

+	}{

+		{name: "diff", operation: func(*testing.T) error {

+			_, err := client.ContainerDiff(ctx, cID)

+			return err

+		}},

+		{name: "export", operation: func(*testing.T) error {

+			rc, err := client.ContainerExport(ctx, cID)

+			if err == nil {

+				defer rc.Close()

+				_, err = io.Copy(io.Discard, rc)

+			}

+			return err

+		}},

+		{name: "cp to container", operation: func(t *testing.T) error {

+			archive, err := archive.Generate("new-file", "hello-world")

+			assert.NilError(t, err, "failed to create a temporary archive")

+			return client.CopyToContainer(ctx, cID, "/", archive, types.CopyToContainerOptions{})

+		}},

+		{name: "cp from container", operation: func(*testing.T) error {

+			rc, _, err := client.CopyFromContainer(ctx, cID, "/file")

+			if err == nil {

+				defer rc.Close()

+				_, err = io.Copy(io.Discard, rc)

+			}

+

+			return err

+		}},

+	}

+

+	for _, tc := range testCases {

+		tc := tc

+		t.Run(tc.name, func(t *testing.T) {

+			prev := dmesgLines(256)

+

+			err := tc.operation(t)

+			assert.NilError(t, err)

+

+			after := dmesgLines(2048)

+

+			diff := diffDmesg(prev, after)

+			for _, line := range diff {

+				overlayfs := strings.Contains(line, "overlayfs: ")

+				lowerDirInUse := strings.Contains(line, "lowerdir is in-use as ")

+				upperDirInUse := strings.Contains(line, "upperdir is in-use as ")

+				workDirInuse := strings.Contains(line, "workdir is in-use as ")

+				undefinedBehavior := strings.Contains(line, "will result in undefined behavior")

+

+				if overlayfs && (lowerDirInUse || upperDirInUse || workDirInuse) && undefinedBehavior {

+					t.Errorf("%s caused overlayfs kernel warning: %s", tc.name, line)

+				}

+			}

+		})

+	}

+}

+

+func dmesgLines(bytes int) []string {

+	data := dmesg.Dmesg(bytes)

+	return strings.Split(strings.TrimSpace(string(data)), "\n")

+}

+

+func diffDmesg(prev, next []string) []string {

+	// All lines have a timestamp, so just take the last one from the previous

+	// log and find it in the new log.

+	lastPrev := prev[len(prev)-1]

+

+	for idx := len(next) - 1; idx >= 0; idx-- {

+		line := next[idx]

+

+		if line == lastPrev {

+			nextIdx := idx + 1

+			if nextIdx < len(next) {

+				return next[nextIdx:]

+			} else {

+				// Found at the last position, log is the same.

+				return nil

+			}

+		}

+	}

+

+	return next

+}