1. 问题描述

云容器中安装了jenkins, 但是在页面上进入"Manage Plugins"的"update"选项卡最下面检查时, 显示:

Update information obtained: N/A ago

但是我实际上填写的Update Site 是能很快访问的

http://updates.jenkins.io/current/update-center.json

2. 问题猜测

所以怀疑是docker内部的jenkins,访问不了上面的网址。为了确认, 我在系统里登录docker查看是否能访问外网:

[root@root ~]$ docker exec -it jenkins /bin/bash
bash-5.1# curl www.baidu.com
curl: (6) Could not resolve host: www.baidu.com

果然访问不了。

3.解决docker内部jenkins不能访问外网地址问题:

3.1 查看宿主机防火墙NAT转发

  • 1.退出docker
    exit
  • 2.检查宿主机防火墙转发

    [root@root ~]$ firewall-cmd --query-masquerade
    FirewallD is not running
    [nie@nie ~]$ systemctl start firewalld.service
    # 切换root身份
    [nie@nie ~]$ su root
    [root@nie nie]# firewall-cmd --query-masquerade
    no

    no 确实没;

    masquerade /ˌmæskəˈreɪd/
    n.掩藏,掩饰;伪装,化装;欺骗;化妆舞会 v.伪装,化装;冒充
    1. 检查配置转发,没有则加入net.ipv4.ip_forward = 1

      sysctl -p
      vi /etc/sysctl.conf
      net.ipv4.ip_forward = 1
    1. 开启转发

      [root@nie nie]# firewall-cmd --add-masquerade --permanent
      success
      [root@nie nie]# firewall-cmd --query-masquerade
      no
      # 需要重新加载
      [root@nie nie]# firewall-cmd --reload
      success
      [root@nie nie]# firewall-cmd --query-masquerade
      yes 
    1. 重启docker
      systemctl restart docker

4. 再试docker内访问外网

[root@nie nie]# docker exec -it jenkins /bin/bash
bash-5.1# curl www.baidu.com
<!DOCTYPE html>
<!--STATUS OK--><html> <head><meta http-equiv=content-type content=text/html;charset=utf-8><meta http-equiv=X-UA-Compatible content=IE=Edge><meta content=always name=referrer><link rel=stylesheet type=text/css href=http://s1.bdstatic.com/r/www/cache/bdorz/baidu.min.css><title>百度一下,你就知道</title></head> <body link=#0000cc> <div id=wrapper> <div id=head> <div class=head_wrapper> <div class=s_form> <div class=s_form_wrapper> <div id=lg> <img hidefocus=true src=//www.baidu.com/img/bd_logo1.png width=270 height=129> </div> <form id=form name=f action=//www.baidu.com/s class=fm> <input type=hidden name=bdorz_come value=1> <input type=hidden name=ie value=utf-8> <input type=hidden name=f value=8> <input type=hidden name=rsv_bp value=1> <input type=hidden name=rsv_idx value=1> <input type=hidden name=tn value=baidu><span class="bg s_ipt_wr"><input id=kw name=wd class=s_ipt value maxlength=255 autocomplete=off autofocus></span><span class="bg s_btn_wr"><input type=submit id=su value=百度一下 class="bg s_btn"></span> </form> </div> </div> <div id=u1> <a href=http://news.baidu.com name=tj_trnews class=mnav>新闻</a> <a href=http://www.hao123.com name=tj_trhao123 class=mnav>hao123</a> <a href=http://map.baidu.com name=tj_trmap class=mnav>地图</a> <a href=http://v.baidu.com name=tj_trvideo class=mnav>视频</a> <a href=http://tieba.baidu.com name=tj_trtieba class=mnav>贴吧</a> <noscript> <a href=http://www.baidu.com/bdorz/login.gif?login&amp;tpl=mn&amp;u=http%3A%2F%2Fwww.baidu.com%2f%3fbdorz_come%3d1 name=tj_login class=lb>登录</a> </noscript> <script>document.write('<a href="http://www.baidu.com/bdorz/login.gif?login&tpl=mn&u='+ encodeURIComponent(window.location.href+ (window.location.search === "" ? "?" : "&")+ "bdorz_come=1")+ '" name="tj_login" class="lb">登录</a>');</script> <a href=//www.baidu.com/more/ name=tj_briicon class=bri style="display: block;">更多产品</a> </div> </div> </div> <div id=ftCon> <div id=ftConw> <p id=lh> <a href=http://home.baidu.com>关于百度</a> <a href=http://ir.baidu.com>About Baidu</a> </p> <p id=cp>&copy;2017&nbsp;Baidu&nbsp;<a href=http://www.baidu.com/duty/>使用百度前必读</a>&nbsp; <a href=http://jianyi.baidu.com/ class=cp-feedback>意见反馈</a>&nbsp;京ICP证030173号&nbsp; <img src=//www.baidu.com/img/gs.gif> </p> </div> </div> </div> </body> </html>

OK finished~


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