fix: set memory swap double of non-zero memory value

daemon/mgr/container_utils.go

@@ -228,6 +228,8 @@ func parsePSOutput(output []byte, pids []int) (*types.ContainerProcessList, erro
 
 // validateConfig validates container config
 func validateConfig(config *types.ContainerCreateConfig) ([]string, error) {
+	amendResource(&config.HostConfig.Resources)
+
 	// validates container hostconfig
 	warnings := make([]string, 0)
 	warns, err := validateResource(&config.HostConfig.Resources)
@@ -262,6 +264,9 @@ func validateResource(r *types.Resources) ([]string, error) {
 			warnings = append(warnings, warn)
 			r.MemorySwap = 0
 		}
+		if r.Memory > 0 && r.MemorySwap > 0 && r.MemorySwap < 2*r.Memory {
+			warnings = append(warnings, "You should typically size your swap space to approximately 2x main memory for systems with less than 2GB of RAM")
+		}
 		if r.MemorySwappiness != nil && !cgroupInfo.Memory.MemorySwappiness {
 			warn := "Current Kernel does not support memory swappiness , discard --memory-swappiness"
 			logrus.Warn(warn)
@@ -362,3 +367,10 @@ func validateResource(r *types.Resources) ([]string, error) {
 
 	return warnings, nil
 }
+
+// amendResource modify resource to correct setting.
+func amendResource(r *types.Resources) {
+	if r.Memory > 0 && r.MemorySwap == 0 {
+		r.MemorySwap = 2 * r.Memory
+	}
+}

daemon/mgr/spec_linux.go

@@ -251,7 +251,7 @@ func setupCPU(ctx context.Context, r types.Resources, s *specs.Spec) {
 // setupResource creates linux memory resource spec.
 func setupMemory(ctx context.Context, r types.Resources, s *specs.Spec) {
 	memory := &specs.LinuxMemory{}
-	if r.Memory != 0 {
+	if r.Memory > 0 {
 		v := r.Memory
 		memory.Limit = &v
 	}

test/cli_run_memory_test.go

@@ -58,6 +58,30 @@ func (suite *PouchRunMemorySuite) TestRunWithMemoryswap(c *check.C) {
 		"/sys/fs/cgroup/memory/default/%s/memory.memsw.limit_in_bytes",
 		containerID)
 	checkFileContains(c, path, "209715200")
+
+	// test memory swap should be 2x memory if not specify it.
+	cname = "TestRunWithMemoryswap2x"
+	res = command.PouchRun("run", "-d", "-m", "10m",
+		"--name", cname, busyboxImage, "sleep", "10000")
+	defer DelContainerForceMultyTime(c, cname)
+	res.Assert(c, icmd.Success)
+
+	// test if the value is in inspect result
+	res = command.PouchRun("inspect", cname)
+	res.Assert(c, icmd.Success)
+
+	result = []types.ContainerJSON{}
+	if err := json.Unmarshal([]byte(res.Stdout()), &result); err != nil {
+		c.Errorf("failed to decode inspect output: %v", err)
+	}
+	c.Assert(result[0].HostConfig.MemorySwap, check.Equals, int64(20971520))
+
+	// test if cgroup has record the real value
+	containerID = result[0].ID
+	path = fmt.Sprintf(
+		"/sys/fs/cgroup/memory/default/%s/memory.memsw.limit_in_bytes",
+		containerID)
+	checkFileContains(c, path, "20971520")
 }
 
 // TestRunWithMemoryswappiness is to verify the valid running container