containerd/pkg/systemd/util.go
Sebastiaan van Stijn 5d31e93787
pkg/systemd: use sync.Once for systemd detection
This brings over the enhancement from a506630e57.

We don't expect the systemd state to change while containerd is running,
so we can use a `sync.Once` for this, to prevent stat'ing each time.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
2023-09-01 12:14:56 +02:00

59 lines
1.8 KiB
Go

//go:build linux
/*
Copyright The containerd Authors.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
// Copyright 2015 CoreOS, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package systemd
import (
"os"
"sync"
)
var (
runningSystemd bool
detectSystemd sync.Once
)
// 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.
// https://github.com/coreos/go-systemd/blob/d843340ab4bd3815fda02e648f9b09ae2dc722a7/util/util.go#L68-L78
func IsRunningSystemd() bool {
detectSystemd.Do(func() {
fi, err := os.Lstat("/run/systemd/system")
if err != nil {
return
}
runningSystemd = fi.IsDir()
})
return runningSystemd
}