Add --device flag to allow additional host devices in container

We add a --device flag which can be used like:

 docker run --device /dev/sda:/dev/xvda:rwm ubuntu /bin/bash

To allow the container to have read write permissions to access the host's /dev/sda via a node named /dev/xvda in the container.

Note: Much of this code was written by Dinesh Subhraveti dineshs@altiscale.com (github: dineshs-altiscale) and so he deserves a ton of credit.

Docker-DCO-1.1-Signed-off-by: Timothy <timothyhobbs@seznam.cz> (github: timthelion)
Upstream-commit: e855c4b92170534864b920ec1e267b3a815764f9
Component: engine

components/engine/integration-cli/docker_cli_run_test.go

@@ -919,6 +919,22 @@ func TestRunUnprivilegedWithChroot(t *testing.T) {
 	logDone("run - unprivileged with chroot")
 }
 
+func TestAddingOptionalDevices(t *testing.T) {
+	cmd := exec.Command(dockerBinary, "run", "--device", "/dev/zero:/dev/nulo", "busybox", "sh", "-c", "ls /dev/nulo")
+
+	out, _, err := runCommandWithOutput(cmd)
+	if err != nil {
+		t.Fatal(err, out)
+	}
+
+	if actual := strings.Trim(out, "\r\n"); actual != "/dev/nulo" {
+		t.Fatalf("expected output /dev/nulo, received %s", actual)
+	}
+	deleteAllContainers()
+
+	logDone("run - test --device argument")
+}
+
 func TestModeHostname(t *testing.T) {
 	cmd := exec.Command(dockerBinary, "run", "-h=testhostname", "busybox", "cat", "/etc/hostname")