docker 动态映射运行的container端口实例详解

2024-09-01 13:48:46

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docker动态映射运行的container端口，最近做项目，对于docker动态映射运行的container端口的资料有必要记录下，以便以后在用到，

Docker自带了EXPOSE命令，可以通过编写dockerfile加-p参数方便的映射Container内部端口，但是对于已经运行的container，如果你想对外开放一个新的端口，只能编辑dockerfile然后重新build，有点不太方便。

其实docker本身使用了iptables来做端口映射的，所以我们可以通过一些简单的操作来实现动态映射运行中的container端口。

通过运行iptables命令可以看到具体的端口映射(下面的实例中IP为192.168.42.41的container开放了22和20280等端口)

[yaxin@ubox ~]$sudo iptables -nvxL Chain INPUT (policy ACCEPT 262 packets, 529689 bytes)   pkts   bytes target   prot opt in   out   source        destination   14355  789552 DROP    tcp -- *   *    0.0.0.0/0      0.0.0.0/0      tcp dpt:25  Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)   pkts   bytes target   prot opt in   out   source        destination  5479459 653248187 DOCKER   all -- *   docker0 0.0.0.0/0      0.0.0.0/0   93990 314970368 ACCEPT   all -- *   docker0 0.0.0.0/0      0.0.0.0/0      ctstate RELATED,ESTABLISHED  4705395 2183219154 ACCEPT   all -- docker0 !docker0 0.0.0.0/0      0.0.0.0/0     0    0 ACCEPT   all -- docker0 docker0 0.0.0.0/0      0.0.0.0/0  Chain OUTPUT (policy ACCEPT 282 packets, 622495 bytes)   pkts   bytes target   prot opt in   out   source        destination  Chain DOCKER (1 references)   pkts   bytes target   prot opt in   out   source        destination    218  13193 ACCEPT   tcp -- !docker0 docker0 0.0.0.0/0      192.168.42.41    tcp dpt:22280  4868186 297463902 ACCEPT   tcp -- !docker0 docker0 0.0.0.0/0      192.168.42.41    tcp dpt:20280   78663 13128102 ACCEPT   tcp -- !docker0 docker0 0.0.0.0/0      192.168.42.41    tcp dpt:22    47   4321 ACCEPT   tcp -- !docker0 docker0 0.0.0.0/0      192.168.42.41    tcp dpt:28159 [yaxin@ubox ~]$sudo iptables -t nat -nvxL Chain PREROUTING (policy ACCEPT 210199 packets, 14035875 bytes)   pkts   bytes target   prot opt in   out   source        destination  1219483 82563968 DOCKER   all -- *   *    0.0.0.0/0      0.0.0.0/0      ADDRTYPE match dst-type LOCAL  Chain INPUT (policy ACCEPT 197679 packets, 13316595 bytes)   pkts   bytes target   prot opt in   out   source        destination  Chain OUTPUT (policy ACCEPT 271553 packets, 16671466 bytes)   pkts   bytes target   prot opt in   out   source        destination   1643  99251 DOCKER   all -- *   *    0.0.0.0/0      !127.0.0.0/8     ADDRTYPE match dst-type LOCAL  Chain POSTROUTING (policy ACCEPT 271743 packets, 16682594 bytes)   pkts   bytes target   prot opt in   out   source        destination   13468  811013 MASQUERADE all -- *   !docker0 192.168.42.0/24   0.0.0.0/0     0    0 MASQUERADE tcp -- *   *    192.168.42.41    192.168.42.41    tcp dpt:22280     0    0 MASQUERADE tcp -- *   *    192.168.42.41    192.168.42.41    tcp dpt:20280     0    0 MASQUERADE tcp -- *   *    192.168.42.41    192.168.42.41    tcp dpt:22     0    0 MASQUERADE tcp -- *   *    192.168.42.41    192.168.42.41    tcp dpt:28159  Chain DOCKER (2 references)   pkts   bytes target   prot opt in   out   source        destination    22   1404 DNAT    tcp -- !docker0 *    0.0.0.0/0      0.0.0.0/0      tcp dpt:22280 to:192.168.42.41:22280    288  17156 DNAT    tcp -- !docker0 *    0.0.0.0/0      0.0.0.0/0      tcp dpt:20280 to:192.168.42.41:20280    93   5952 DNAT    tcp -- !docker0 *    0.0.0.0/0      0.0.0.0/0      tcp dpt:22222 to:192.168.42.41:22     8   512 DNAT    tcp -- !docker0 *    0.0.0.0/0      0.0.0.0/0      tcp dpt:28159 to:192.168.42.41:28159

我们要做的就是根据自己container的情况配置iptables规则。

首先是filter这个表，我们要配置其放通转发，docker默认已经将所有的FORWARD规则放到了DOCKER这个自建链(chain)中了，这样方便配置，也方便查看。

然后再配置nat表为其配置DNAT，这个才是端口转发的核心配置。这个表中只需要配置POSTROUTING和DOCKER链即可，这里不讲为什么这么配置，如果想要深入了解iptables请google一下。

下面举个例子：

假如我有一个container，名字为nginx(通过运行docker ps命令即可查询)，现在我在docker内部运行nginx程序，监听了8888端口，我希望外网可以通过8899端口(注意一下端口)访问

找到docker为nginx分配的IP

[yaxin@ubox ~]$sudo docker inspect -f '{{.NetworkSettings.IPAddress}}' nginx192.168.42.43

配置iptables中filter表的FORWARD(DOCKER)链

[yaxin@ubox ~]$sudo iptables -A DOCKER ! -i docker0 -o docker0 -p tcp --dport 8888 -d 192.168.42.43 -j ACCEPT

配置iptables中nat表的PREROUTING(DOCKER)和POSTROUTING链

[yaxin@ubox ~]$sudo iptables -t nat -A POSTROUTING -p tcp --dport 8888 -s 192.168.42.43 -d 192.168.42.43 -j MASQUERADE[yaxin@ubox ~]$sudo iptables -t nat -A DOCKER ! -i dokcer0 -p tcp --dport 8899 -j DNAT --to-destination 192.168.42.43:8888

通过外网访问curl http://IP:8899就会显示nginx下配置的html页面

最后iptables规则

[yaxin@ubox ~]$sudo iptables -nvxL Chain INPUT (policy ACCEPT 67893 packets, 212661547 bytes)   pkts   bytes target   prot opt in   out   source        destination   14364  790008 DROP    tcp -- *   *    0.0.0.0/0      0.0.0.0/0      tcp dpt:25  Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)   pkts   bytes target   prot opt in   out   source        destination  5479682 653269356 DOCKER   all -- *   docker0 0.0.0.0/0      0.0.0.0/0   94186 314986910 ACCEPT   all -- *   docker0 0.0.0.0/0      0.0.0.0/0      ctstate RELATED,ESTABLISHED  4705658 2183254076 ACCEPT   all -- docker0 !docker0 0.0.0.0/0      0.0.0.0/0     0    0 ACCEPT   all -- docker0 docker0 0.0.0.0/0      0.0.0.0/0  Chain OUTPUT (policy ACCEPT 71253 packets, 222512872 bytes)   pkts   bytes target   prot opt in   out   source        destination  Chain DOCKER (1 references)   pkts   bytes target   prot opt in   out   source        destination    218  13193 ACCEPT   tcp -- !docker0 docker0 0.0.0.0/0      192.168.42.41    tcp dpt:22280  4868186 297463902 ACCEPT   tcp -- !docker0 docker0 0.0.0.0/0      192.168.42.41    tcp dpt:20280   78663 13128102 ACCEPT   tcp -- !docker0 docker0 0.0.0.0/0      192.168.42.41    tcp dpt:22    47   4321 ACCEPT   tcp -- !docker0 docker0 0.0.0.0/0      192.168.42.41    tcp dpt:28159    27   4627 ACCEPT   tcp -- !docker0 docker0 0.0.0.0/0      192.168.42.43    tcp dpt:8888 [yaxin@ubox ~]$sudo iptables -t nat -nvxL Chain PREROUTING (policy ACCEPT 232 packets, 16606 bytes)   pkts   bytes target   prot opt in   out   source        destination  1220281 82620790 DOCKER   all -- *   *    0.0.0.0/0      0.0.0.0/0      ADDRTYPE match dst-type LOCAL  Chain INPUT (policy ACCEPT 216 packets, 15671 bytes)   pkts   bytes target   prot opt in   out   source        destination  Chain OUTPUT (policy ACCEPT 317 packets, 19159 bytes)   pkts   bytes target   prot opt in   out   source        destination   1644  99311 DOCKER   all -- *   *    0.0.0.0/0      !127.0.0.0/8     ADDRTYPE match dst-type LOCAL  Chain POSTROUTING (policy ACCEPT 321 packets, 19367 bytes)   pkts   bytes target   prot opt in   out   source        destination   13512  813656 MASQUERADE all -- *   !docker0 192.168.42.0/24   0.0.0.0/0     0    0 MASQUERADE tcp -- *   *    192.168.42.41    192.168.42.41    tcp dpt:22280     0    0 MASQUERADE tcp -- *   *    192.168.42.41    192.168.42.41    tcp dpt:20280     0    0 MASQUERADE tcp -- *   *    192.168.42.41    192.168.42.41    tcp dpt:22     0    0 MASQUERADE tcp -- *   *    192.168.42.41    192.168.42.41    tcp dpt:28159     0    0 MASQUERADE tcp -- *   *    192.168.42.43    192.168.42.43    tcp dpt:8888  Chain DOCKER (2 references)   pkts   bytes target   prot opt in   out   source        destination    22   1404 DNAT    tcp -- !docker0 *    0.0.0.0/0      0.0.0.0/0      tcp dpt:22280 to:192.168.42.41:22280    288  17156 DNAT    tcp -- !docker0 *    0.0.0.0/0      0.0.0.0/0      tcp dpt:20280 to:192.168.42.41:20280    93   5952 DNAT    tcp -- !docker0 *    0.0.0.0/0      0.0.0.0/0      tcp dpt:22222 to:192.168.42.41:22     8   512 DNAT    tcp -- !docker0 *    0.0.0.0/0      0.0.0.0/0      tcp dpt:28159 to:192.168.42.41:28159     4   208 DNAT    tcp -- !dokcer0 *    0.0.0.0/0      0.0.0.0/0      tcp dpt:8899 to:192.168.42.43:8888

当然，使用手动配置也是比较麻烦的，所以我写了一个脚本来自动配置端口映射，使用方法脚本中有说明

#!/bin/bash # filename: docker_expose.sh  if [ `id -u` -ne 0 ];then   echo "[EROOR] Please use root to run this script"   exit 23 fi  if [ $# -ne 3 ];then   echo "Usage: $0 <container_name> <add|del> [[<machine_ip>:]<machine_port>:]<container_port>[/<protocol_type>]"   exit 1 fi  IPV4_RE='(([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])/.){3}([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])'  container_name=$1 action=$2 arguments=$3  # check action if [ "$action"x != "add"x -a "$action"x != "del"x ];then   echo "[ERROR] Please use add or del parameter to add port map or delete port map"   exit 654 fi if [ "$action"x == "add"x ];then   action="A" else   action="D" fi  # get container ip by container name container_ip=`docker inspect -f '{{.NetworkSettings.IPAddress}}' $container_name 2> /dev/null` if [ -z $container_ip ];then   echo "[ERROR] Get container's (${container_name}) IP error, please ensure you have this container"   exit 2 fi  # parse arguments protocol_type=`echo $arguments | awk -F '/' '{print $2}'` if [ -z $protocol_type ];then   protocol_type="tcp" fi  # check protocol if [ "$protocol_type"x != "tcp"x -a "$protocol_type"x != "udp"x ];then   echo "[ERROR] Only tcp or udp protocol is allowed"   exit 99 fi  machine_ip='' machine_port='' container_port='' # split the left arguments arguments=${arguments%/*} machine_ip=`echo $arguments | awk -F ':' '{print $1}'` machine_port=`echo $arguments | awk -F ':' '{print $2}'` container_port=`echo $arguments | awk -F ':' '{print $3}'` if [ -z $machine_port ];then   # arguments is: 234   container_port=$machine_ip   machine_port=$machine_ip   unset machine_ip elif [ -z $container_port ];then   # arguments is: 234:456   container_port=$machine_ip   machine_port=$machine_port   unset machine_ip fi  # check port number function _check_port_number() {   local port_num=$1   if ! echo $port_num | egrep "^[0-9]+$" &> /dev/null;then     echo "[ERROR] Invalid port number $port_num"     exit 3   fi   if [ $port_num -gt 65535 -o $port_num -lt 1 ];then     echo "[ERROR] Port number $port_num is out of range(1-56635)"     exit 4   fi }  # check port and ip address _check_port_number $container_port _check_port_number $machine_port  if [ ! -z $machine_ip ];then   if ! echo $machine_ip | egrep "^${IPV4_RE}$" &> /dev/null;then     echo "[ERROR] Invalid Ip Adress $machine_ip"     exit 5   fi    # check which interface bind the IP   for interface in `ifconfig -s | sed -n '2,$p' | awk '{print $1}'`;do     interface_ip=`ifconfig $interface | awk '/inet addr/{print substr($2,6)}'`     if [ "$interface_ip"x == "$machine_ip"x ];then       interface_name=$interface       break     fi   done    if [ -z $interface_name ];then     echo "[ERROR] Can not find interface bind with $machine_ip"     exit 98   fi fi  # run iptables command echo "[INFO] Now start to change rules to iptables" echo "[INFO] Changing POSTROUTING chain of nat table" iptables -t nat -${action} POSTROUTING -p ${protocol_type} --dport ${container_port} -s ${container_ip} -d ${container_ip} -j MASQUERADE if [ -z $interface_name ];then   echo "[INFO] Changing DOCKER chain of filter table"   iptables -${action} DOCKER ! -i docker0 -o docker0 -p ${protocol_type} --dport ${container_port} -d ${container_ip} -j ACCEPT   echo "[INFO] Changing DOCKER chain of nat table"   iptables -t nat -${action} DOCKER ! -i docker0 -p ${protocol_type} --dport ${machine_port} -j DNAT --to-destination ${container_ip}:${container_port} else   echo "[INFO] Changing DOCKER chain of filter table"   iptables -${action} DOCKER -i $interface_name -o docker0 -p ${protocol_type} --dport ${container_port} -d ${container_ip} -j ACCEPT   echo "[INFO] Changing DOCKER chain of nat table"   iptables -t nat -${action} DOCKER -i $interface_name -p ${protocol_type} --dport ${machine_port} -j DNAT --to-destination ${container_ip}:${container_port} fi

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