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Merged
dashpole merged 3 commits into from
Nov 6, 2017
Merged

libcontainer: Use first cgroup subsystem found #1792

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79ef9d4
libcontainer: Use first cgroup subsystem found
euank Nov 6, 2017
ee7ccd6
libcontainer: add CgroupSubsystems unit tests
euank Nov 6, 2017
1141915
libcontainer: log skipped cgroup subsystems
euank Nov 6, 2017
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21 changes: 19 additions & 2 deletions container/libcontainer/helpers.go
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Original file line number Diff line number Diff line change
Expand Up @@ -55,19 +55,36 @@ func GetCgroupSubsystems() (CgroupSubsystems, error) {
if err != nil {
return CgroupSubsystems{}, err
}

return getCgroupSubsystemsHelper(allCgroups)
}

func getCgroupSubsystemsHelper(allCgroups []cgroups.Mount) (CgroupSubsystems, error) {
if len(allCgroups) == 0 {
return CgroupSubsystems{}, fmt.Errorf("failed to find cgroup mounts")
}

// Trim the mounts to only the subsystems we care about.
supportedCgroups := make([]cgroups.Mount, 0, len(allCgroups))
recordedMountpoints := make(map[string]struct{}, len(allCgroups))
mountPoints := make(map[string]string, len(allCgroups))
for _, mount := range allCgroups {
for _, subsystem := range mount.Subsystems {
if _, ok := supportedSubsystems[subsystem]; ok {
if _, ok := supportedSubsystems[subsystem]; !ok {
// Unsupported subsystem
continue
}
if _, ok := mountPoints[subsystem]; ok {
// duplicate mount for this subsystem; use the first one we saw
glog.V(5).Infof("skipping %s, already using mount at %s", mount.Mountpoint, mountPoints[subsystem])
continue
}
if _, ok := recordedMountpoints[mount.Mountpoint]; !ok {
// avoid appending the same mount twice in e.g. `cpu,cpuacct` case
supportedCgroups = append(supportedCgroups, mount)
mountPoints[subsystem] = mount.Mountpoint
recordedMountpoints[mount.Mountpoint] = struct{}{}
}
mountPoints[subsystem] = mount.Mountpoint
}
}

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107 changes: 107 additions & 0 deletions container/libcontainer/helpers_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -15,7 +15,12 @@
package libcontainer

import (
"fmt"
"os"
"path/filepath"
"reflect"
"sort"
"strings"
"testing"

info "github.com/google/cadvisor/info/v1"
Expand Down Expand Up @@ -134,3 +139,105 @@ func TestMorePossibleCPUs(t *testing.T) {
t.Fatalf("expected %+v == %+v", ret, expected)
}
}

var defaultCgroupSubsystems = []string{
"systemd", "freezer", "memory", "blkio", "hugetlb", "net_cls,net_prio", "pids", "cpu,cpuacct", "devices", "cpuset", "perf_events",
}

func cgroupMountsAt(path string, subsystems []string) []cgroups.Mount {
res := []cgroups.Mount{}
for _, subsystem := range subsystems {
res = append(res, cgroups.Mount{
Root: "/",
Subsystems: strings.Split(subsystem, ","),
Mountpoint: filepath.Join(path, subsystem),
})
}
return res
}

func TestGetCgroupSubsystems(t *testing.T) {
ourSubsystems := []string{"cpu,cpuacct", "devices", "memory", "cpuset", "blkio"}

testCases := []struct {
mounts []cgroups.Mount
expected CgroupSubsystems
err bool
}{
{
mounts: []cgroups.Mount{},
err: true,
},
{
// normal case
mounts: cgroupMountsAt("/sys/fs/cgroup", defaultCgroupSubsystems),
expected: CgroupSubsystems{
MountPoints: map[string]string{
"blkio": "/sys/fs/cgroup/blkio",
"cpu": "/sys/fs/cgroup/cpu,cpuacct",
"cpuacct": "/sys/fs/cgroup/cpu,cpuacct",
"cpuset": "/sys/fs/cgroup/cpuset",
"devices": "/sys/fs/cgroup/devices",
"memory": "/sys/fs/cgroup/memory",
},
Mounts: cgroupMountsAt("/sys/fs/cgroup", ourSubsystems),
},
},
{
// multiple croup subsystems, should ignore second one
mounts: append(cgroupMountsAt("/sys/fs/cgroup", defaultCgroupSubsystems),
cgroupMountsAt("/var/lib/rkt/pods/run/ccdd4e36-2d4c-49fd-8b94-4fb06133913d/stage1/rootfs/opt/stage2/flannel/rootfs/sys/fs/cgroup", defaultCgroupSubsystems)...),
expected: CgroupSubsystems{
MountPoints: map[string]string{
"blkio": "/sys/fs/cgroup/blkio",
"cpu": "/sys/fs/cgroup/cpu,cpuacct",
"cpuacct": "/sys/fs/cgroup/cpu,cpuacct",
"cpuset": "/sys/fs/cgroup/cpuset",
"devices": "/sys/fs/cgroup/devices",
"memory": "/sys/fs/cgroup/memory",
},
Mounts: cgroupMountsAt("/sys/fs/cgroup", ourSubsystems),
},
},
{
// most subsystems not mounted
mounts: append(cgroupMountsAt("/sys/fs/cgroup", []string{"cpu"})),
expected: CgroupSubsystems{
MountPoints: map[string]string{
"cpu": "/sys/fs/cgroup/cpu",
},
Mounts: cgroupMountsAt("/sys/fs/cgroup", []string{"cpu"}),
},
},
}

for i, testCase := range testCases {
subSystems, err := getCgroupSubsystemsHelper(testCase.mounts)
if testCase.err {
if err == nil {
t.Fatalf("[case %d] Expected error but didn't get one", i)
}
continue
}
if err != nil {
t.Fatalf("[case %d] Expected no error, but got %v", i, err)
}
assertCgroupSubsystemsEqual(t, testCase.expected, subSystems, fmt.Sprintf("[case %d]", i))
}
}

func assertCgroupSubsystemsEqual(t *testing.T, expected, actual CgroupSubsystems, message string) {
if !reflect.DeepEqual(expected.MountPoints, actual.MountPoints) {
t.Fatalf("%s Expected %v == %v", message, expected.MountPoints, actual.MountPoints)
}

sort.Slice(expected.Mounts, func(i, j int) bool {
return expected.Mounts[i].Mountpoint < expected.Mounts[j].Mountpoint
})
sort.Slice(actual.Mounts, func(i, j int) bool {
return actual.Mounts[i].Mountpoint < actual.Mounts[j].Mountpoint
})
if !reflect.DeepEqual(expected.Mounts, actual.Mounts) {
t.Fatalf("%s Expected %v == %v", message, expected.Mounts, actual.Mounts)
}
}