Kubernetes 中 Nginx 配置热加载
转自：运维研习社
Nginx本身是支持热更新的，通过nginx -s reload指令，实际通过向进程发送HUB信号实现不停服重新加载配置，然而在Docker或者Kubernetes中，每次都需要进容器执行nginx -s reload指令，单docker容器还好说，可以在外面通过exec指定容器执行该指令进行热加载，Kubernetes的话，就比较难受了
今天介绍一下Kubernetes中Nginx热加载配置的处理方法——reloader
reloader地址：https://github.com/stakater/Reloader
reloader主要就是用来监测ConfigMap或Secret的变化，然后对相关DeploymentConfig的Deployment、DaemonSet执行滚动升级
reloader需要kubernetes1.9以上的版本才支持
使用方法
首先是安装部署reloader
# 直接通过官方yaml文件部署
kubectl apply -f https://raw.githubusercontent.com/stakater/Reloader/master/deployments/kubernetes/reloader.yaml
默认情况下reloader是部署在default命名空间，但是它是监控所有命名空间的configmaps和secrets
当然，如果不想监控某个configmap或secret，可以通过--resources-to-ignore=configMaps/secrets来忽略某个资源
部署成功后，就可以直接使用了，我提前部署了nginx和configmap
这是目前的配置，看一下Nginx目前的配置
接着，我修改Nginx的Deployment，添加reloader，监听nginx-config这个ConfigMap，执行reload
{
"kind": "Deployment",
"apiVersion": "extensions/v1beta1",
"metadata": {
"name": "nginx",
"namespace": "default",
"selfLink": "/apis/extensions/v1beta1/namespaces/default/deployments/nginx",
"uid": "7eee5fa8-7514-11ec-a916-0210d5e9ca3b",
"resourceVersion": "286141",
"generation": 10,
"creationTimestamp": "2022-01-14T08:32:23Z",
"labels": {
"k8s-app": "nginx"
},
"annotations": {
"deployment.kubernetes.io/revision": "9",
"description": "nginx应用"
# 主要是这行
"reloader.stakater.com/reload": "nginx-config"
}
},
"spec": {
"replicas": 1,
"selector": {
"matchLabels": {
"k8s-app": "nginx"
}
}
……
然后apply该Deployment，之后我们去更新ConfigMap，更新nginx配置文件
更新完成，去掉proxy_redirect，然后去看nginx容器是否执行滚动更新
可以看到，nginx执行了滚动更新，接着看下nginx配置文件是否更新
这样很简单的通过reloader就可以实现Nginx的配置热加载
除了这种方法，常见的方法还有使用sidecar，通过sidecar去做的话，需要自己写监听脚本，比较麻烦，但是有时候也相对灵活，这里也附一个sidecar的python脚本
#!/usr/bin/env python
# -*- encoding: utf8 -*-
"""
需求：nginx配置文件变化，自动更新配置文件，类似nginx -s reload
实现：
1、用pyinotify实时监控nginx配置文件变化
2、如果配置文件变化，给系统发送HUP来reload nginx
"""
import os
import re
import pyinotify
import logging
from threading import Timer
# Param
LOG_PATH = "/root/python/log"
CONF_PATHS = [
"/etc/nginx",
]
DELAY = 5
SUDO = False
RELOAD_COMMAND = "nginx -s reload"
if SUDO:
RELOAD_COMMAND = "sudo " + RELOAD_COMMAND
# Log
logger = logging.getLogger(__name__)
logger.setLevel(level = logging.INFO)
log_handler = logging.FileHandler(LOG_PATH)
log_handler.setLevel(logging.INFO)
log_formatter = logging.Formatter('%(asctime)s - %(levelname)s - %(message)s')
log_handler.setFormatter(log_formatter)
logger.addHandler(log_handler)
# Reloader
def reload_nginx():
os.system(RELOAD_COMMAND)
logger.info("nginx is reloaded")
t = Timer(DELAY, reload_nginx)
def trigger_reload_nginx(pathname, action):
logger.info("nginx monitor is triggered because %s is %s" % (pathname, action))
global t
if t.is_alive():
t.cancel()
t = Timer(DELAY, reload_nginx)
t.start()
else:
t = Timer(DELAY, reload_nginx)
t.start()
events = pyinotify.IN_MODIFY | pyinotify.IN_CREATE | pyinotify.IN_DELETE
watcher = pyinotify.WatchManager()
watcher.add_watch(CONF_PATHS, events, rec=True, auto_add=True)
class EventHandler(pyinotify.ProcessEvent):
def process_default(self, event):
if event.name.endswith(".conf"):
if event.mask == pyinotify.IN_CREATE:
action = "created"
if event.mask == pyinotify.IN_MODIFY:
action = "modified"
if event.mask == pyinotify.IN_DELETE:
action = "deleted"
trigger_reload_nginx(event.pathname, action)
handler = EventHandler()
notifier = pyinotify.Notifier(watcher, handler)
# Start
logger.info("Start Monitoring")
notifier.loop()
如果喜欢用go的，这里也提供go脚本
package main
import (
"log"
"os"
"path/filepath"
"syscall"
"github.com/fsnotify/fsnotify"
proc "github.com/shirou/gopsutil/process"
)
const (
nginxProcessName = "nginx"
defaultNginxConfPath = "/etc/nginx"
watchPathEnvVarName = "WATCH_NGINX_CONF_PATH"
)
var stderrLogger = log.New(os.Stderr, "error: ", log.Lshortfile)
var stdoutLogger = log.New(os.Stdout, "", log.Lshortfile)
func getMasterNginxPid() (int, error) {
processes, processesErr := proc.Processes()
if processesErr != nil {
return 0, processesErr
}
nginxProcesses := map[int32]int32{}
for _, process := range processes {
processName, processNameErr := process.Name()
if processNameErr != nil {
return 0, processNameErr
}
if processName == nginxProcessName {
ppid, ppidErr := process.Ppid()
if ppidErr != nil {
return 0, ppidErr
}
nginxProcesses[process.Pid] = ppid
}
}
var masterNginxPid int32
for pid, ppid := range nginxProcesses {
if ppid == 0 {
masterNginxPid = pid
break
}
}
stdoutLogger.Println("found master nginx pid:", masterNginxPid)
return int(masterNginxPid), nil
}
func signalNginxReload(pid int) error {
stdoutLogger.Printf("signaling master nginx process (pid: %d) -> SIGHUP\n", pid)
nginxProcess, nginxProcessErr := os.FindProcess(pid)
if nginxProcessErr != nil {
return nginxProcessErr
}
return nginxProcess.Signal(syscall.SIGHUP)
}
func main() {
watcher, watcherErr := fsnotify.NewWatcher()
if watcherErr != nil {
stderrLogger.Fatal(watcherErr)
}
defer watcher.Close()
done := make(chan bool)
go func() {
for {
select {
case event, ok := <-watcher.Events:
if !ok {
return
}
if event.Op&fsnotify.Create == fsnotify.Create {
if filepath.Base(event.Name) == "..data" {
stdoutLogger.Println("config map updated")
nginxPid, nginxPidErr := getMasterNginxPid()
if nginxPidErr != nil {
stderrLogger.Printf("getting master nginx pid failed: %s", nginxPidErr.Error())
continue
}
if err := signalNginxReload(nginxPid); err != nil {
stderrLogger.Printf("signaling master nginx process failed: %s", err)
}
}
}
case err, ok := <-watcher.Errors:
if !ok {
return
}
stderrLogger.Printf("received watcher.Error: %s", err)
}
}
}()
pathToWatch, ok := os.LookupEnv(watchPathEnvVarName)
if !ok {
pathToWatch = defaultNginxConfPath
}
stdoutLogger.Printf("adding path: `%s` to watch\n", pathToWatch)
if err := watcher.Add(pathToWatch); err != nil {
stderrLogger.Fatal(err)
}
<-done
}
ok,今天的内容就到这里
END
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