From 81e961cc149fbccd60b968c2089f856e41105954 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Pawe=C5=82=20Gronowski?= <pawel.gronowski@docker.com>
Date: Mon, 5 Jun 2023 17:45:22 +0200
Subject: [PATCH] mount: Add `volume-subpath` option
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Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com>
---
 e2e/container/run_test.go | 37 +++++++++++++++++++++++++++++++++++++
 opts/mount.go             |  2 ++
 2 files changed, 39 insertions(+)

diff --git a/e2e/container/run_test.go b/e2e/container/run_test.go
index 3b0414ffab1c..11fd1bef67d3 100644
--- a/e2e/container/run_test.go
+++ b/e2e/container/run_test.go
@@ -2,6 +2,7 @@ package container
 
 import (
 	"fmt"
+	"strings"
 	"testing"
 
 	"github.com/docker/cli/e2e/internal/fixtures"
@@ -148,3 +149,39 @@ func TestRunWithCgroupNamespace(t *testing.T) {
 		"/bin/grep", "-q", "':memory:/$'", "/proc/1/cgroup")
 	result.Assert(t, icmd.Success)
 }
+
+func TestMountSubvolume(t *testing.T) {
+	volName := "test-volume-" + t.Name()
+	icmd.RunCommand("docker", "volume", "create", volName).Assert(t, icmd.Success)
+
+	t.Cleanup(func() {
+		icmd.RunCommand("docker", "volume", "remove", "-f", volName).Assert(t, icmd.Success)
+	})
+
+	defaultMountOpts := []string{
+		"type=volume",
+		"src=" + volName,
+		"dst=/volume",
+	}
+
+	// Populate the volume with test data.
+	icmd.RunCommand("docker", "run", "--mount", strings.Join(defaultMountOpts, ","), fixtures.AlpineImage, "sh", "-c",
+		"echo foo > /volume/bar.txt && "+
+			"mkdir /volume/subdir && echo world > /volume/subdir/hello.txt;",
+	).Assert(t, icmd.Success)
+
+	runMount := func(cmd string, mountOpts ...string) *icmd.Result {
+		mountArg := strings.Join(append(defaultMountOpts, mountOpts...), ",")
+		return icmd.RunCommand("docker", "run", "--mount", mountArg, fixtures.AlpineImage, cmd, "/volume")
+	}
+
+	t.Run("subpath not exists", func(t *testing.T) {
+		runMount("ls", "volume-subpath=some-path/that/doesnt-exist").Assert(t, icmd.Expected{Err: "volume's path is not accessible", ExitCode: 125})
+	})
+	t.Run("subdirectory mount", func(t *testing.T) {
+		runMount("ls", "volume-subpath=subdir").Assert(t, icmd.Expected{Out: "hello.txt"})
+	})
+	t.Run("file mount", func(t *testing.T) {
+		runMount("cat", "volume-subpath=bar.txt").Assert(t, icmd.Expected{Out: "foo"})
+	})
+}
diff --git a/opts/mount.go b/opts/mount.go
index 2b531127ebdb..241eb8791277 100644
--- a/opts/mount.go
+++ b/opts/mount.go
@@ -112,6 +112,8 @@ func (m *MountOpt) Set(value string) error {
 			if err != nil {
 				return fmt.Errorf("invalid value for %s: %s", key, val)
 			}
+		case "volume-subpath":
+			volumeOptions().SubPath = val
 		case "volume-nocopy":
 			volumeOptions().NoCopy, err = strconv.ParseBool(val)
 			if err != nil {