现象

• 某个同学执行docker启动容器的时候提示

docker: Error response from daemon: driver failed programming external connectivity on endpoint frosty_montalcini (5f23d1b819d9b55a229a9fb789c7f0897123b7e218694eefbc31487e8e4883a6):  (iptables failed: iptables --wait -t nat -A DOCKER -p tcp -d 0/0 --dport 8082 -j DNAT --to-destination 172.17.0.5:80 ! -i docker0: iptables: No chain/target/match by that name.
 (exit status 1)).

• 这个报错Error response from daemon提示是daemon给了一个错误的响应

• daemon是这个

  [root@qianhanyi ~]# ps -ef|grep dockerd
  root      16921      1  2 04:12 ?        00:00:00 /usr/bin/dockerd -H fd:// --containerd=/run/containerd/containerd.sock
  
  

• 为何能给response，因为dockerd是个RESTful的API server

  [root@qianhanyi ~]# docker version
  Client: Docker Engine - Community
   Version:           23.0.1
   API version:       1.42  # 这里
  
  # 有空考虑写一个api操作docker的文章
  

• 报错提到了iptables，这是关键线索

现场还原

以centos7为例

• 确保你的firewalld正常

  [root@qianhanyi ~]# systemctl status firewalld
  ● firewalld.service - firewalld - dynamic firewall daemon
     Loaded: loaded (/usr/lib/systemd/system/firewalld.service; enabled; vendor preset: enabled)
     Active: active (running) since Fri 2022-11-18 04:12:19 CST; 7min ago
       Docs: man:firewalld(1)
   Main PID: 16655 (firewalld)
      Tasks: 2
     Memory: 23.6M
     CGroup: /system.slice/firewalld.service
             └─16655 /usr/bin/python2 -Es /usr/sbin/firewalld --nofork --nopid
  
  ...
  Hint: Some lines were ellipsized, use -l to show in full.
  
  

• 运行一个容器，比如nginx的

  [root@qianhanyi ~]# docker run -itd -p 8082:80 nginx
  253fe5d60b8446612ae76bee9476eeb96b3c294b46a7c87c3c21ffe26dcaa1ec
  [root@qianhanyi ~]# docker ps -a
  CONTAINER ID   IMAGE      COMMAND                  CREATED          STATUS         PORTS                                       NAMES
  253fe5d60b84   nginx      "/docker-entrypoint.…"   4 seconds ago    Up 3 seconds   0.0.0.0:8082->80/tcp, :::8082->80/tcp       infallible_pasteur
  
  

• 浏览器访问ip:8082，可能会无法访问

• 此时你想到了防火墙的原因

• 停了吧

  [root@qianhanyi ~]# systemctl stop firewalld
  [root@qianhanyi ~]# systemctl status firewalld
  ● firewalld.service - firewalld - dynamic firewall daemon
     Loaded: loaded (/usr/lib/systemd/system/firewalld.service; enabled; vendor preset: enabled)
     Active: inactive (dead) since Fri 2022-11-18 04:26:36 CST; 8s ago
       Docs: man:firewalld(1)
    Process: 16655 ExecStart=/usr/sbin/firewalld --nofork --nopid $FIREWALLD_ARGS (code=exited, status=0/SUCCESS)
   Main PID: 16655 (code=exited, status=0/SUCCESS)
  
  ...
  Nov 18 04:26:35 qianhanyi systemd[1]: Stopping firewalld - dynamic firewall daemon...
  Nov 18 04:26:36 qianhanyi systemd[1]: Stopped firewalld - dynamic firewall daemon.
  Hint: Some lines were ellipsized, use -l to show in full.
  
  

• 此时应该能访问了

• 过了一会，你又启动了一个容器

  [root@qianhanyi ~]#  docker run -itd -p 8083:80 nginx
  4a7658f1669a76fd990e5757afe8c32d09fee6bf6b6fa55426e2abf0d88f29e0
  docker: Error response from daemon: driver failed programming external connectivity on endpoint gracious_sutherland (0f46051611e83ef3e69c84bc17b2ef4f60ca03fe729020ba8348c2f845f0d26f):  (iptables failed: iptables --wait -t nat -A DOCKER -p tcp -d 0/0 --dport 8083 -j DNAT --to-destination 172.17.0.5:80 ! -i docker0: iptables: No chain/target/match by that name.
   (exit status 1)).
  
  

• 至此复现了问题

解决

• 此时你只需重启下docker应用程序

  [root@qianhanyi ~]# systemctl restart docker
  
  # 当然你要关注下，你之前启动的其他容器有没有配置--restart=always， 如果没有那些容器记得需要的话启动下
  

• 再次启动容器

  [root@qianhanyi ~]#  docker run -itd -p 8083:80 nginx
  803cfa1c24b7c1a0934551fa19915c9abee1b22a2ed8a7a86268a9b244c88e7e
  
  

思考

• docker 是有网络的，容器网络实质上是由 Dokcer 为应用程序所创造的虚拟环境的一部分，它能让应用从宿主机操作系统的网络环境中独立出来，形成容器自有的网络设备、IP 协议栈、端口套接字、IP 路由表、防火墙等等与网络相关的模块。
• 本质的原因本文还是没找到
• docker网络这部分也可以单独拉出来讲一个篇幅