SebastianCzoch/lxc-exporter

package lxc

import (
    "fmt"
    "io/ioutil"
    "regexp"
    "strings"
)

// ProcStat is a method which represent cpu stats from cgroups
type ProcStat struct {
    User   float64
    System float64
}

var (
    lxcCPUStatPathPattern = map[int]string{
        3: "%s/lxc/%s/cpuacct.stat",
        4: "%s/cpu,cpuacct/lxc/%s/cpuacct.stat",
    }
)

// GetProcStat is a method which returns ProcStat struct for selected container
func (l *LXC) GetProcStat(containerName string) (ProcStat, error) {
    if !l.containerExists(containerName) {
        return ProcStat{}, errorContainerNotFound
    }

    cpuStat, err := l.fetchProcStat(containerName)
    if err != nil {
        return ProcStat{}, err
    }

    return parseProcStat(cpuStat), nil
}

func (l *LXC) fetchProcStat(containerName string) ([]byte, error) {
    path, err := l.getCPUStatPath(containerName)
    if err != nil {
        return []byte{}, err
    }

    return ioutil.ReadFile(path)
}

func (l *LXC) getCPUStatPath(containerName string) (string, error) {
    if _, ok := lxcCPUStatPathPattern[l.kernelVersion]; !ok {
        return "", errorKernelNotSupported
    }

    return fmt.Sprintf(lxcCPUStatPathPattern[l.kernelVersion], cgroupPath, containerName), nil
}

func parseProcStat(content []byte) ProcStat {
    reg := regexp.MustCompile("\\s\\s+")
    content = reg.ReplaceAll(content, []byte(" "))
    lines := strings.Split(string(content), "\n")
    user := strings.Split(lines[0], " ")
    system := strings.Split(lines[1], " ")

    return ProcStat{User: forceToFloat64(user[1]), System: forceToFloat64(system[1])}
}