Fix missing "--version" argument

Commit 858b4b44c8 added
support for obtaining the runtime version
if a custom path was set, but accidentally
removed the "--version" flag.

This patch restores the flag, and adds an integration
test to verify the behavior..

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

daemon/info_unix.go

@@ -38,7 +38,7 @@ func (daemon *Daemon) FillPlatformInfo(v *types.Info, sysInfo *sysinfo.SysInfo)
 
 	v.RuncCommit.Expected = dockerversion.RuncCommitID
 	defaultRuntimeBinary := daemon.configStore.GetRuntime(daemon.configStore.GetDefaultRuntimeName()).Path
-	if rv, err := exec.Command(defaultRuntimeBinary).Output(); err == nil {
+	if rv, err := exec.Command(defaultRuntimeBinary, "--version").Output(); err == nil {
 		parts := strings.Split(strings.TrimSpace(string(rv)), "\n")
 		if len(parts) == 3 {
 			parts = strings.Split(parts[1], ": ")

integration-cli/docker_api_info_test.go

@@ -3,8 +3,11 @@ package main
 import (
 	"net/http"
 
+	"encoding/json"
+	"github.com/docker/docker/api/types"
 	"github.com/docker/docker/integration-cli/checker"
 	"github.com/docker/docker/integration-cli/request"
+	"github.com/docker/docker/pkg/testutil"
 	"github.com/go-check/check"
 )
 
@@ -40,6 +43,25 @@ func (s *DockerSuite) TestInfoAPI(c *check.C) {
 	}
 }
 
+// TestInfoAPIRuncCommit tests that dockerd is able to obtain RunC version
+// information, and that the version matches the expected version
+func (s *DockerSuite) TestInfoAPIRuncCommit(c *check.C) {
+	testRequires(c, DaemonIsLinux) // Windows does not have RunC version information
+
+	res, body, err := request.Get("/v1.30/info")
+	c.Assert(res.StatusCode, checker.Equals, http.StatusOK)
+	c.Assert(err, checker.IsNil)
+
+	b, err := testutil.ReadBody(body)
+	c.Assert(err, checker.IsNil)
+
+	var i types.Info
+
+	c.Assert(json.Unmarshal(b, &i), checker.IsNil)
+	c.Assert(i.RuncCommit.ID, checker.Not(checker.Equals), "N/A")
+	c.Assert(i.RuncCommit.ID, checker.Equals, i.RuncCommit.Expected)
+}
+
 func (s *DockerSuite) TestInfoAPIVersioned(c *check.C) {
 	testRequires(c, DaemonIsLinux) // Windows only supports 1.25 or later
 	endpoint := "/v1.20/info"