dockerutil: Add IsGVisorRuntime helper function.

This is useful for CUDA tests, some of which work in gVisor and some not.
By checking whether the runtime in use is gVisor, the test can adjust its
expectations of success/failure.

PiperOrigin-RevId: 626443132

pkg/test/dockerutil/container.go

@@ -207,11 +207,13 @@ func (c *Container) Run(ctx context.Context, r RunOpts, args ...string) (string,
 	}
 
 	if err := c.Start(ctx); err != nil {
-		return "", err
+		logs, _ := c.Logs(ctx)
+		return logs, err
 	}
 
 	if err := c.Wait(ctx); err != nil {
-		return "", err
+		logs, _ := c.Logs(ctx)
+		return logs, err
 	}
 
 	return c.Logs(ctx)

pkg/test/dockerutil/dockerutil.go

@@ -16,6 +16,7 @@
 package dockerutil
 
 import (
+	"context"
 	"encoding/json"
 	"flag"
 	"fmt"
@@ -27,6 +28,7 @@ import (
 	"regexp"
 	"strconv"
 	"strings"
+	"testing"
 	"time"
 
 	"gvisor.dev/gvisor/pkg/test/testutil"
@@ -122,6 +124,19 @@ func RuntimePath() (string, error) {
 	return p, nil
 }
 
+// IsGVisorRuntime returns whether the default container runtime used by
+// `dockerutil` is gVisor-based or not.
+func IsGVisorRuntime(ctx context.Context, t *testing.T) (bool, error) {
+	output, err := MakeContainer(ctx, t).Run(ctx, RunOpts{Image: "basic/alpine"}, "dmesg")
+	if err != nil {
+		if strings.Contains(output, "dmesg: klogctl: Operation not permitted") {
+			return false, nil
+		}
+		return false, fmt.Errorf("failed to run dmesg: %v (output: %q)", err, output)
+	}
+	return strings.Contains(output, "gVisor"), nil
+}
+
 // UsingSystemdCgroup returns true if the docker configuration has the
 // native.cgroupdriver=systemd option set in "exec-opts", or if the
 // system is using cgroupv2, in which case systemd is the default driver.