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When working on a project, the dynamically mapped container ports of docker are forIt is necessary to record the information of dynamically mapped container ports of docker, for future reference.
Docker comes with the EXPOSE command, which can be used by writing a dockerfile and}}-The p parameter is convenient for mapping the internal port of the container, but for a running container, if you want to open a new port for external access, you need to edit the dockerfile and rebuild it, which is not very convenient.
In fact, docker itself uses iptables for port mapping, so we can implement dynamic port mapping of running containers through some simple operations.
You can see the specific port mapping by running the iptables command (the IP in the following example is192.168.42.41container has opened22and2028(0th port)
[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
What we need to do is to configure the iptables rules according to the situation of our container.
Firstly, the filter table, we need to configure it to allow forwarding. By default, docker has already placed all the FORWARD rules into the DOCKER built-in chain (chain), which is convenient for configuration and viewing.
Then configure the nat table to set up DNAT, which is the core configuration for port forwarding. This table only needs to configure POSTROUTING and DOCKER chains, and why this configuration is done is not discussed here. If you want to learn more about iptables, please google it.
Here is an example:
Suppose I have a container named nginx (you can query by running the docker ps command), now I am running the nginx program inside docker, listening to8888Port, I hope the external network can access8899Port (note the port) access
Find the IP assigned to nginx by docker
[yaxin@ubox ~]$sudo docker inspect -f '{{.NetworkSettings.IPAddress}}' nginx
192.168.42.43
Configure the FORWARD (DOCKER) chain in the filter table of iptables
[yaxin@ubox ~]$sudo iptables -A DOCKER ! -i docker0 -o docker0 -p tcp --dport 8888 -d 192.168.42.43 -j ACCEPT
Configure the PREROUTING (DOCKER) and POSTROUTING chains in the nat table of iptables
[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
Access through the external network curl http://IP:8899It will display the html page configured under nginx
Last iptables rule
[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
Of course, manual configuration is also quite麻烦, so I wrote a script to automatically configure port mapping, the usage is described in the script
#!/bin/bash
# filename: docker_expose.sh
if [ `id -u` -ne 0 ];then
echo "[ERROR] 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 Address $machine_ip"
exit 5
fi
# check which interface binds the IP
for interface in `ifconfig -s | sed -n '2',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
Thank you for reading, I hope it can help everyone. Thank you for your support of this site!