Add support for setting rlimit for contianer

Adds a new item to the config struct []*Rlimit
Rlimit takes a type (ie, syscall.RLIMIT_NOFILE) and the hard/soft limit
(As max/cur)

Signed-off-by: Brian Goff <cpuguy83@gmail.com>

config.go

@@ -68,6 +68,10 @@ type Config struct {
 	// RestrictSys will remount /proc/sys, /sys, and mask over sysrq-trigger as well as /proc/irq and
 	// /proc/bus
 	RestrictSys bool `json:"restrict_sys,omitempty"`
+
+	// Rlimits specifies the resource limits, such as max open files, to set in the container
+	// If Rlimits are not set, the container will inherit rlimits from the parent process
+	Rlimits []Rlimit `json:"rlimits,omitempty"`
 }
 
 // Routes can be specified to create entries in the route table as the container is started
@@ -90,3 +94,9 @@ type Route struct {
 	// The device to set this route up for, for example: eth0
 	InterfaceName string `json:"interface_name,omitempty"`
 }
+
+type Rlimit struct {
+	Type int    `json:"type,omitempty"`
+	Hard uint64 `json:"hard,omitempty"`
+	Soft uint64 `json:"soft,omitempty"`
+}

integration/exec_test.go

@@ -156,3 +156,24 @@ func TestIPCBadPath(t *testing.T) {
 		t.Fatal("container succeded with bad ipc path")
 	}
 }
+
+func TestRlimit(t *testing.T) {
+	if testing.Short() {
+		return
+	}
+
+	rootfs, err := newRootFs()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer remove(rootfs)
+
+	config := newTemplateConfig(rootfs)
+	out, _, err := runContainer(config, "", "/bin/sh", "-c", "ulimit -n")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if limit := strings.TrimSpace(out.Stdout.String()); limit != "1024" {
+		t.Fatalf("expected rlimit to be 1024, got %s", limit)
+	}
+}

integration/template_test.go

@@ -1,6 +1,8 @@
 package integration
 
 import (
+	"syscall"
+
 	"github.com/docker/libcontainer"
 	"github.com/docker/libcontainer/cgroups"
 	"github.com/docker/libcontainer/devices"
@@ -60,5 +62,12 @@ func newTemplateConfig(rootfs string) *libcontainer.Config {
 				Gateway: "localhost",
 			},
 		},
+		Rlimits: []libcontainer.Rlimit{
+			{
+				Type: syscall.RLIMIT_NOFILE,
+				Hard: uint64(1024),
+				Soft: uint64(1024),
+			},
+		},
 	}
 }

namespaces/init.go

@@ -89,6 +89,10 @@ func Init(container *libcontainer.Config, uncleanRootfs, consolePath string, pip
 		return fmt.Errorf("setup route %s", err)
 	}
 
+	if err := setupRlimits(container); err != nil {
+		return fmt.Errorf("setup rlimits %s", err)
+	}
+
 	label.Init()
 
 	if err := mount.InitializeMountNamespace(rootfs,
@@ -238,6 +242,16 @@ func setupRoute(container *libcontainer.Config) error {
 	return nil
 }
 
+func setupRlimits(container *libcontainer.Config) error {
+	for _, rlimit := range container.Rlimits {
+		l := &syscall.Rlimit{Max: rlimit.Hard, Cur: rlimit.Soft}
+		if err := syscall.Setrlimit(rlimit.Type, l); err != nil {
+			return fmt.Errorf("error setting rlimit type %v: %v", rlimit.Type, err)
+		}
+	}
+	return nil
+}
+
 // FinalizeNamespace drops the caps, sets the correct user
 // and working dir, and closes any leaky file descriptors
 // before execing the command inside the namespace