Kubernetes中Nginx配置热加载的全过程
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 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
总结
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