daemon: execdriver: lxc: fix set memory swap

On LXC memory swap was only set to memory_limit*2 even if a value for
memory swap was provided. This patch fix this behavior to be the same
as the native driver and set correct memory swap in the template.
Also add a test specifically for LXC but w/o adding a new test
requirement.

Signed-off-by: Antonio Murdaca <runcom@linux.com>

daemon/execdriver/lxc/lxc_template.go

@@ -91,9 +91,9 @@ lxc.mount.entry = {{$value.Source}} {{escapeFstabSpaces $ROOTFS}}/{{escapeFstabS
 {{if .Resources}}
 {{if .Resources.Memory}}
 lxc.cgroup.memory.limit_in_bytes = {{.Resources.Memory}}
-{{with $memSwap := getMemorySwap .Resources}}
-lxc.cgroup.memory.memsw.limit_in_bytes = {{$memSwap}}
 {{end}}
+{{if gt .Resources.MemorySwap 0}}
+lxc.cgroup.memory.memsw.limit_in_bytes = {{.Resources.MemorySwap}}
 {{end}}
 {{if gt .Resources.MemoryReservation 0}}
 lxc.cgroup.memory.soft_limit_in_bytes = {{.Resources.MemoryReservation}}
@@ -209,15 +209,6 @@ func isDirectory(source string) string {
 	return "file"
 }
 
-func getMemorySwap(v *execdriver.Resources) int64 {
-	// By default, MemorySwap is set to twice the size of RAM.
-	// If you want to omit MemorySwap, set it to `-1'.
-	if v.MemorySwap < 0 {
-		return 0
-	}
-	return v.Memory * 2
-}
-
 func getLabel(c map[string][]string, name string) string {
 	label := c["label"]
 	for _, l := range label {
@@ -242,7 +233,6 @@ func getHostname(env []string) string {
 func init() {
 	var err error
 	funcMap := template.FuncMap{
-		"getMemorySwap":     getMemorySwap,
 		"escapeFstabSpaces": escapeFstabSpaces,
 		"formatMountLabel":  label.FormatMountLabel,
 		"isDirectory":       isDirectory,

daemon/execdriver/lxc/lxc_template_unit_test.go

@@ -34,6 +34,7 @@ func TestLXCConfig(t *testing.T) {
 		memMin = 33554432
 		memMax = 536870912
 		mem    = memMin + r.Intn(memMax-memMin)
+		swap   = memMax
 		cpuMin = 100
 		cpuMax = 10000
 		cpu    = cpuMin + r.Intn(cpuMax-cpuMin)
@@ -46,8 +47,9 @@ func TestLXCConfig(t *testing.T) {
 	command := &execdriver.Command{
 		ID: "1",
 		Resources: &execdriver.Resources{
-			Memory:    int64(mem),
-			CPUShares: int64(cpu),
+			Memory:     int64(mem),
+			MemorySwap: int64(swap),
+			CPUShares:  int64(cpu),
 		},
 		Network: &execdriver.Network{
 			Mtu: 1500,
@@ -63,7 +65,7 @@ func TestLXCConfig(t *testing.T) {
 		fmt.Sprintf("lxc.cgroup.memory.limit_in_bytes = %d", mem))
 
 	grepFile(t, p,
-		fmt.Sprintf("lxc.cgroup.memory.memsw.limit_in_bytes = %d", mem*2))
+		fmt.Sprintf("lxc.cgroup.memory.memsw.limit_in_bytes = %d", swap))
 }
 
 func TestCustomLxcConfig(t *testing.T) {

integration-cli/docker_cli_run_unix_test.go

@@ -17,6 +17,7 @@ import (
 	"github.com/docker/docker/pkg/mount"
 	"github.com/docker/docker/pkg/parsers"
 	"github.com/docker/docker/pkg/sysinfo"
+	"github.com/docker/docker/pkg/units"
 	"github.com/go-check/check"
 	"github.com/kr/pty"
 )
@@ -435,3 +436,22 @@ func (s *DockerSuite) TestRunInvalidCPUShares(c *check.C) {
 	expected = "The maximum allowed cpu-shares is"
 	c.Assert(out, checker.Contains, expected)
 }
+
+func (s *DockerSuite) TestRunWithCorrectMemorySwapOnLXC(c *check.C) {
+	testRequires(c, memoryLimitSupport)
+	testRequires(c, swapMemorySupport)
+	testRequires(c, SameHostDaemon)
+
+	out, _ := dockerCmd(c, "run", "-d", "-m", "16m", "--memory-swap", "64m", "busybox", "top")
+	if _, err := os.Stat("/sys/fs/cgroup/memory/lxc"); err != nil {
+		c.Skip("Excecution driver must be LXC for this test")
+	}
+	id := strings.TrimSpace(out)
+	memorySwap, err := ioutil.ReadFile(fmt.Sprintf("/sys/fs/cgroup/memory/lxc/%s/memory.memsw.limit_in_bytes", id))
+	c.Assert(err, check.IsNil)
+	cgSwap, err := strconv.ParseInt(strings.TrimSpace(string(memorySwap)), 10, 64)
+	c.Assert(err, check.IsNil)
+	swap, err := units.RAMInBytes("64m")
+	c.Assert(err, check.IsNil)
+	c.Assert(cgSwap, check.Equals, swap)
+}