Move sysinfo out of daemon struct

sysinfo struct was initialized at daemon startup to make sure
kernel configs such as device cgroup are present and error out if not.
The struct was embedded in daemon struct making impossible to detect
if some system config is changed at daemon runtime (i.e. someone
umount the memory cgroup). This leads to container's starts failure if
some config is changed at daemon runtime.
This patch moves sysinfo out of daemon and initilize and check it when
needed (daemon startup, containers creation, contaienrs startup for
now).

Signed-off-by: Antonio Murdaca <runcom@linux.com>
(cherry picked from commit 472b6f66e03f9a85fe8d23098dac6f55a87456d8)

daemon/daemon.go

@@ -92,7 +92,6 @@ type Daemon struct {
 	graph            *graph.Graph
 	repositories     *graph.TagStore
 	idIndex          *truncindex.TruncIndex
-	sysInfo          *sysinfo.SysInfo
 	config           *Config
 	containerGraph   *graphdb.Database
 	driver           graphdriver.Driver
@@ -725,7 +724,6 @@ func NewDaemon(config *Config, registryService *registry.Service) (daemon *Daemo
 	d.graph = g
 	d.repositories = repositories
 	d.idIndex = truncindex.NewTruncIndex([]string{})
-	d.sysInfo = sysInfo
 	d.config = config
 	d.sysInitPath = sysInitPath
 	d.execDriver = ed
@@ -858,10 +856,6 @@ func (daemon *Daemon) Config() *Config {
 	return daemon.config
 }
 
-func (daemon *Daemon) SystemConfig() *sysinfo.SysInfo {
-	return daemon.sysInfo
-}
-
 func (daemon *Daemon) SystemInitPath() string {
 	return daemon.sysInitPath
 }

daemon/daemon_unix.go

@@ -18,6 +18,7 @@ import (
 	"github.com/docker/docker/pkg/fileutils"
 	"github.com/docker/docker/pkg/parsers"
 	"github.com/docker/docker/pkg/parsers/kernel"
+	"github.com/docker/docker/pkg/sysinfo"
 	"github.com/docker/docker/pkg/system"
 	"github.com/docker/docker/runconfig"
 	"github.com/docker/docker/utils"
@@ -148,7 +149,8 @@ func (daemon *Daemon) adaptContainerSettings(hostConfig *runconfig.HostConfig, a
 // verifyPlatformContainerSettings performs platform-specific validation of the
 // hostconfig and config structures.
 func verifyPlatformContainerSettings(daemon *Daemon, hostConfig *runconfig.HostConfig, config *runconfig.Config) ([]string, error) {
-	var warnings []string
+	warnings := []string{}
+	sysInfo := sysinfo.New(false)
 
 	if hostConfig.LxcConf.Len() > 0 && !strings.Contains(daemon.ExecutionDriver().Name(), "lxc") {
 		return warnings, fmt.Errorf("Cannot use --lxc-conf with execdriver: %s", daemon.ExecutionDriver().Name())
@@ -156,12 +158,12 @@ func verifyPlatformContainerSettings(daemon *Daemon, hostConfig *runconfig.HostC
 	if hostConfig.Memory != 0 && hostConfig.Memory < 4194304 {
 		return warnings, fmt.Errorf("Minimum memory limit allowed is 4MB")
 	}
-	if hostConfig.Memory > 0 && !daemon.SystemConfig().MemoryLimit {
+	if hostConfig.Memory > 0 && !sysInfo.MemoryLimit {
 		warnings = append(warnings, "Your kernel does not support memory limit capabilities. Limitation discarded.")
 		logrus.Warnf("Your kernel does not support memory limit capabilities. Limitation discarded.")
 		hostConfig.Memory = 0
 	}
-	if hostConfig.Memory > 0 && hostConfig.MemorySwap != -1 && !daemon.SystemConfig().SwapLimit {
+	if hostConfig.Memory > 0 && hostConfig.MemorySwap != -1 && !sysInfo.SwapLimit {
 		warnings = append(warnings, "Your kernel does not support swap limit capabilities, memory limited without swap.")
 		logrus.Warnf("Your kernel does not support swap limit capabilities, memory limited without swap.")
 		hostConfig.MemorySwap = -1
@@ -172,7 +174,7 @@ func verifyPlatformContainerSettings(daemon *Daemon, hostConfig *runconfig.HostC
 	if hostConfig.Memory == 0 && hostConfig.MemorySwap > 0 {
 		return warnings, fmt.Errorf("You should always set the Memory limit when using Memoryswap limit, see usage.")
 	}
-	if hostConfig.MemorySwappiness != nil && !daemon.SystemConfig().MemorySwappiness {
+	if hostConfig.MemorySwappiness != nil && !sysInfo.MemorySwappiness {
 		warnings = append(warnings, "Your kernel does not support memory swappiness capabilities, memory swappiness discarded.")
 		logrus.Warnf("Your kernel does not support memory swappiness capabilities, memory swappiness discarded.")
 		hostConfig.MemorySwappiness = nil
@@ -183,28 +185,28 @@ func verifyPlatformContainerSettings(daemon *Daemon, hostConfig *runconfig.HostC
 			return warnings, fmt.Errorf("Invalid value: %v, valid memory swappiness range is 0-100.", swappiness)
 		}
 	}
-	if hostConfig.CPUShares > 0 && !daemon.SystemConfig().CPUShares {
+	if hostConfig.CPUShares > 0 && !sysInfo.CPUShares {
 		warnings = append(warnings, "Your kernel does not support CPU shares. Shares discarded.")
 		logrus.Warnf("Your kernel does not support CPU shares. Shares discarded.")
 		hostConfig.CPUShares = 0
 	}
-	if hostConfig.CPUPeriod > 0 && !daemon.SystemConfig().CPUCfsPeriod {
+	if hostConfig.CPUPeriod > 0 && !sysInfo.CPUCfsPeriod {
 		warnings = append(warnings, "Your kernel does not support CPU cfs period. Period discarded.")
 		logrus.Warnf("Your kernel does not support CPU cfs period. Period discarded.")
 		hostConfig.CPUPeriod = 0
 	}
-	if hostConfig.CPUQuota > 0 && !daemon.SystemConfig().CPUCfsQuota {
+	if hostConfig.CPUQuota > 0 && !sysInfo.CPUCfsQuota {
 		warnings = append(warnings, "Your kernel does not support CPU cfs quota. Quota discarded.")
 		logrus.Warnf("Your kernel does not support CPU cfs quota. Quota discarded.")
 		hostConfig.CPUQuota = 0
 	}
-	if (hostConfig.CpusetCpus != "" || hostConfig.CpusetMems != "") && !daemon.SystemConfig().Cpuset {
+	if (hostConfig.CpusetCpus != "" || hostConfig.CpusetMems != "") && !sysInfo.Cpuset {
 		warnings = append(warnings, "Your kernel does not support cpuset. Cpuset discarded.")
 		logrus.Warnf("Your kernel does not support cpuset. Cpuset discarded.")
 		hostConfig.CpusetCpus = ""
 		hostConfig.CpusetMems = ""
 	}
-	if hostConfig.BlkioWeight > 0 && !daemon.SystemConfig().BlkioWeight {
+	if hostConfig.BlkioWeight > 0 && !sysInfo.BlkioWeight {
 		warnings = append(warnings, "Your kernel does not support Block I/O weight. Weight discarded.")
 		logrus.Warnf("Your kernel does not support Block I/O weight. Weight discarded.")
 		hostConfig.BlkioWeight = 0
@@ -212,11 +214,11 @@ func verifyPlatformContainerSettings(daemon *Daemon, hostConfig *runconfig.HostC
 	if hostConfig.BlkioWeight > 0 && (hostConfig.BlkioWeight < 10 || hostConfig.BlkioWeight > 1000) {
 		return warnings, fmt.Errorf("Range of blkio weight is from 10 to 1000.")
 	}
-	if hostConfig.OomKillDisable && !daemon.SystemConfig().OomKillDisable {
+	if hostConfig.OomKillDisable && !sysInfo.OomKillDisable {
 		hostConfig.OomKillDisable = false
 		return warnings, fmt.Errorf("Your kernel does not support oom kill disable.")
 	}
-	if daemon.SystemConfig().IPv4ForwardingDisabled {
+	if sysInfo.IPv4ForwardingDisabled {
 		warnings = append(warnings, "IPv4 forwarding is disabled. Networking will not work.")
 		logrus.Warnf("IPv4 forwarding is disabled. Networking will not work")
 	}

daemon/info.go

@@ -11,6 +11,7 @@ import (
 	"github.com/docker/docker/pkg/fileutils"
 	"github.com/docker/docker/pkg/parsers/kernel"
 	"github.com/docker/docker/pkg/parsers/operatingsystem"
+	"github.com/docker/docker/pkg/sysinfo"
 	"github.com/docker/docker/pkg/system"
 	"github.com/docker/docker/registry"
 	"github.com/docker/docker/utils"
@@ -56,15 +57,17 @@ func (daemon *Daemon) SystemInfo() (*types.Info, error) {
 		initPath = daemon.SystemInitPath()
 	}
 
+	sysInfo := sysinfo.New(false)
+
 	v := &types.Info{
 		ID:                 daemon.ID,
 		Containers:         len(daemon.List()),
 		Images:             imgcount,
 		Driver:             daemon.GraphDriver().String(),
 		DriverStatus:       daemon.GraphDriver().Status(),
-		IPv4Forwarding:     !daemon.SystemConfig().IPv4ForwardingDisabled,
-		BridgeNfIptables:   !daemon.SystemConfig().BridgeNfCallIptablesDisabled,
-		BridgeNfIp6tables:  !daemon.SystemConfig().BridgeNfCallIP6tablesDisabled,
+		IPv4Forwarding:     !sysInfo.IPv4ForwardingDisabled,
+		BridgeNfIptables:   !sysInfo.BridgeNfCallIptablesDisabled,
+		BridgeNfIp6tables:  !sysInfo.BridgeNfCallIP6tablesDisabled,
 		Debug:              os.Getenv("DEBUG") != "",
 		NFd:                fileutils.GetTotalUsedFds(),
 		NGoroutines:        runtime.NumGoroutine(),
@@ -90,11 +93,11 @@ func (daemon *Daemon) SystemInfo() (*types.Info, error) {
 	// sysinfo.cgroupCpuInfo will be nil otherwise and cause a SIGSEGV if
 	// an attempt is made to access through them.
 	if runtime.GOOS != "windows" {
-		v.MemoryLimit = daemon.SystemConfig().MemoryLimit
-		v.SwapLimit = daemon.SystemConfig().SwapLimit
-		v.OomKillDisable = daemon.SystemConfig().OomKillDisable
-		v.CpuCfsPeriod = daemon.SystemConfig().CPUCfsPeriod
-		v.CpuCfsQuota = daemon.SystemConfig().CPUCfsQuota
+		v.MemoryLimit = sysInfo.MemoryLimit
+		v.SwapLimit = sysInfo.SwapLimit
+		v.OomKillDisable = sysInfo.OomKillDisable
+		v.CpuCfsPeriod = sysInfo.CPUCfsPeriod
+		v.CpuCfsQuota = sysInfo.CPUCfsQuota
 	}
 
 	if httpProxy := os.Getenv("http_proxy"); httpProxy != "" {

pkg/sysinfo/sysinfo_linux.go

@@ -10,7 +10,9 @@ import (
 	"github.com/opencontainers/runc/libcontainer/cgroups"
 )
 
-// New returns a new SysInfo, using the filesystem to detect which features the kernel supports.
+// New returns a new SysInfo, using the filesystem to detect which features
+// the kernel supports. If `quiet` is `false` warnings are printed in logs
+// whenever an error occurs or misconfigurations are present.
 func New(quiet bool) *SysInfo {
 	sysInfo := &SysInfo{}
 	sysInfo.cgroupMemInfo = checkCgroupMem(quiet)