SebastianCzoch/lxc-exporter

package lxc

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

// MemStat is a struct which contains usage of memory read from cgroups
type MemStat struct {
    Usage float64
}

var (
    lxcMemStatPathPattern = map[int]string{
        4: "%s/memory/lxc/%s/memory.usage_in_bytes",
    }
)

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

    memStat, err := l.fetchMemStat(containerName)
    if err != nil {
        return MemStat{}, err
    }

    return parseMemStat(memStat), nil
}

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

    return ioutil.ReadFile(path)
}

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

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

func parseMemStat(content []byte) MemStat {
    s := strings.Replace(string(content), "\n", "", -1)
    return MemStat{Usage: forceToFloat64(s)}
}