需求：利用go语言获取linux主机的cpu利用率及内存使用量和剩余量，并将其制作成exporter
编写go代码及注解如下：
package main
import (
"bufio"
"io/ioutil"
"net/http"
"os"
"fmt"
"strconv"
"strings"
"time"
)
func getCPUSample() (idle, total uint64) {
//读取/proc/stat内容
contents, err := ioutil.ReadFile("/proc/stat")
if err != nil {
return
}
//读取内容转化为字符串
lines := strings.Split(string(contents), "\n")
for _, line := range(lines) {
//将字符串以空白字符（\t, \n, \v, \f, \r, ’ ‘, U+0085 (NEL), U+00A0 (NBSP) 。）进行分割多个子串
fields := strings.Fields(line)
//如果第一列字符为“cpu”
if fields[0] == "cpu" {
//统计子串数量
numFields := len(fields)
for i := 1; i < numFields; i++ {
val, err := strconv.ParseUint(fields[i], 10, 64)
if err != nil {
fmt.Println("Error: ", i, fields[i], err)
}
//将是CPU字符的所有子串相加
total += val // tally up all the numbers to get total ticks
if i == 4 { // idle is the 5th field in the cpu line
//第五列的数据赋值给idle
idle = val
}
}
return
}
}
return
}
func ReadLine(lineNumber int) string{
//读取/proc/meminfo内容
file, _ := os.Open("/proc/meminfo")
//按行读取所有内容
fileScanner := bufio.NewScanner(file)
lineCount := 1
for fileScanner.Scan(){
if lineCount == lineNumber{
return fileScanner.Text()
}
lineCount++
}
defer file.Close()
return ""
}
func handler(w http.ResponseWriter, r *http.Request) {
//定义一个整数型切片
var s []int
//读取/proc/meminfo的第二行内容
MemFree := ReadLine(2)
//将读取的内容转化为字符串
MemFree_lines := strings.Split(string(MemFree), "\n")
//将字符串以空白字符（\t, \n, \v, \f, \r, ’ ‘, U+0085 (NEL), U+00A0 (NBSP) 。）进行分割多个子串
for _, MemFree_line := range (MemFree_lines) {
fields := strings.Fields(MemFree_line)
//将第二列的内容转化为整数，并将这个整数追加到s切片中
if MemFree_line, err := strconv.Atoi(fields[1]); err == nil {
//fmt.Printf("%T, %v", MemFree_line, MemFree_line)
s = append(s, MemFree_line)
}
}
Buffers := ReadLine(4)
Buffers_lines := strings.Split(string(Buffers), "\n")
for _, Buffers_line := range (Buffers_lines) {
fields := strings.Fields(Buffers_line)
if Buffers_line, err := strconv.Atoi(fields[1]); err == nil {
//fmt.Printf("%T, %v", Buffers_line, Buffers_line)
s = append(s, Buffers_line)
}
}
Cached := ReadLine(4)
Cached_lines := strings.Split(string(Cached), "\n")
for _, Cached_line := range (Cached_lines) {
fields := strings.Fields(Cached_line)
if Cached_line, err := strconv.Atoi(fields[1]); err == nil {
//fmt.Printf("%T, %v", Cached_line, Cached_line)
s = append(s, Cached_line)
}
}
MemTotal := ReadLine(1)
MemTotal_lines := strings.Split(string(MemTotal), "\n")
for _, MemTotal_line := range (MemTotal_lines) {
fields := strings.Fields(MemTotal_line)
if MemTotal_line, err := strconv.Atoi(fields[1]); err == nil {
//fmt.Printf("%T, %v", MemTotal_line, MemTotal_line)
s = append(s, MemTotal_line)
}
}
idle0, total0 := getCPUSample()
time.Sleep(3 * time.Second)
idle1, total1 := getCPUSample()
idleTicks := float64(idle1 - idle0)
totalTicks := float64(total1 - total0)
//计算cpu利用率
cpuUsage := 100 * (totalTicks - idleTicks) / totalTicks
//计算内存的使用率及剩余量
memoryused := (s[0] + s[1] + s[2])
memoryfreeused:=(s[3]-memoryused)
//页面显示内容
fmt.Fprintf(w,"#HELP node_memory_guest_seconds\n node_memory{key=\"used\"}\t%v\n node_memory{key=\"free\"}\t%v\n#node_CPU_guest_seconds\n node_cpu{key=\"usage\"}\t%v\n",memoryused,memoryfreeused,cpuUsage)
}
func main(){
//调用handler函数
http.HandleFunc("/", handler)
//端口为8006
http.ListenAndServe(":8006", nil)
}
执行并打开页面（每次加载页面会自动刷新数据值）：
[root@localhost ~]# go run exporter_cpu_memory.go
[root@localhost ~]# curl 127.0.0.1:8006
#HELP node_memory_guest_seconds
node_memory{key="used"} 117864
node_memory{key="free"} 878060
#node_CPU_guest_seconds
node_cpu{key="usage"} 0
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