Kubernetes中Nginx配置热加载的过程是怎样的，很多新手对此不是很清楚，为了帮助大家解决这个难题，下面小编将为大家详细讲解，有这方面需求的人可以来学习下，希望你能有所收获。
前言
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 osimport reimport pyinotifyimport loggingfrom threading import Timer# ParamLOG_PATH = "/root/python/log"CONF_PATHS = [ "/etc/nginx",]DELAY = 5SUDO = FalseRELOAD_COMMAND = "nginx -s reload"if SUDO: RELOAD_COMMAND = "sudo " + RELOAD_COMMAND# Loglogger = 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)# Reloaderdef 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_DELETEwatcher = 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)# Startlogger.info("Start Monitoring")notifier.loop()如果喜欢用go的，这里也提供go脚本
package mainimport ( "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
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