runc/libcontainer/cgroups/systemd/common.go

102 lines
2.8 KiB
Go

package systemd
import (
"fmt"
"os"
"strings"
"sync"
systemdDbus "github.com/coreos/go-systemd/v22/dbus"
dbus "github.com/godbus/dbus/v5"
"github.com/opencontainers/runc/libcontainer/configs"
)
var (
connOnce sync.Once
connDbus *systemdDbus.Conn
connErr error
)
// NOTE: This function comes from package github.com/coreos/go-systemd/util
// It was borrowed here to avoid a dependency on cgo.
//
// IsRunningSystemd checks whether the host was booted with systemd as its init
// system. This functions similarly to systemd's `sd_booted(3)`: internally, it
// checks whether /run/systemd/system/ exists and is a directory.
// http://www.freedesktop.org/software/systemd/man/sd_booted.html
func IsRunningSystemd() bool {
fi, err := os.Lstat("/run/systemd/system")
if err != nil {
return false
}
return fi.IsDir()
}
// systemd represents slice hierarchy using `-`, so we need to follow suit when
// generating the path of slice. Essentially, test-a-b.slice becomes
// /test.slice/test-a.slice/test-a-b.slice.
func ExpandSlice(slice string) (string, error) {
suffix := ".slice"
// Name has to end with ".slice", but can't be just ".slice".
if len(slice) < len(suffix) || !strings.HasSuffix(slice, suffix) {
return "", fmt.Errorf("invalid slice name: %s", slice)
}
// Path-separators are not allowed.
if strings.Contains(slice, "/") {
return "", fmt.Errorf("invalid slice name: %s", slice)
}
var path, prefix string
sliceName := strings.TrimSuffix(slice, suffix)
// if input was -.slice, we should just return root now
if sliceName == "-" {
return "/", nil
}
for _, component := range strings.Split(sliceName, "-") {
// test--a.slice isn't permitted, nor is -test.slice.
if component == "" {
return "", fmt.Errorf("invalid slice name: %s", slice)
}
// Append the component to the path and to the prefix.
path += "/" + prefix + component + suffix
prefix += component + "-"
}
return path, nil
}
// getDbusConnection lazy initializes systemd dbus connection
// and returns it
func getDbusConnection() (*systemdDbus.Conn, error) {
connOnce.Do(func() {
connDbus, connErr = systemdDbus.New()
})
return connDbus, connErr
}
func newProp(name string, units interface{}) systemdDbus.Property {
return systemdDbus.Property{
Name: name,
Value: dbus.MakeVariant(units),
}
}
func getUnitName(c *configs.Cgroup) string {
// by default, we create a scope unless the user explicitly asks for a slice.
if !strings.HasSuffix(c.Name, ".slice") {
return fmt.Sprintf("%s-%s.scope", c.ScopePrefix, c.Name)
}
return c.Name
}
// isUnitExists returns true if the error is that a systemd unit already exists.
func isUnitExists(err error) bool {
if err != nil {
if dbusError, ok := err.(dbus.Error); ok {
return strings.Contains(dbusError.Name, "org.freedesktop.systemd1.UnitExists")
}
}
return false
}