containerpaths.go

package containertools

import (
	"io/ioutil"
	"strings"
)

const croot = "/proc/1/cgroup" // No idea what we do for Windows.

// Containerpaths returns a pointer to a list of cgroups, one per entry in
//  /proc/1/cgroup.  If their GroupIDs are all "/", you're not running
//  in a container.  If you get an error, you are not running a Linux that
//  supports containerization, or the format of /proc/1/cgroup isn't what
//  we were expecting.  If the file is empty, you will get no error, but
//  a nil pointer.  That is the case, for instance, on Debian Wheezy.
func Containerpaths() (*[]Cgroup, error) {
	b, err := ioutil.ReadFile(croot)
	if err != nil {
		return nil, err
	}
	inp := strings.Split(string(b), "\n")
	var r []Cgroup
	for _, v := range inp {
		s := strings.TrimSpace(v)
		if s == "" {
			continue
		}
		pcg, err := Parse(s)
		if err != nil {
			return nil, err
		}
		r = append(r, *pcg)
	}
	if len(r) == 0 {
		return nil, nil
	}
	return &r, nil
}