Docker容器内部端口映射到外部宿主机端口 - 运维笔记

 

Docker允许通过外部访问容器或者容器之间互联的方式来提供网络服务。
容器启动之后,容器中可以运行一些网络应用,通过-p或-P参数来指定端口映射。

注意:
宿主机的一个端口只能映射到容器内部的某一个端口上,比如:8080->80之后,就不能8080->81
容器内部的某个端口可以被宿主机的多个端口映射,比如:8080->80,8090->80,8099->80

1)启动容器时,选择一个端口映射到容器内部开放端口上
-p   小写p表示docker会选择一个具体的宿主机端口映射到容器内部开放的网络端口上。
-P   大写P表示docker会随机选择一个宿主机端口映射到容器内部开放的网络端口上。

比如:
[root@docker-test ~]# docker run -ti -d --name my-nginx -p 8088:80 docker.io/nginx
2218c7d88ccc917fd0aa0ec24e6d81667eb588f491d3730deb09289dcf6b8125
[root@docker-test ~]# docker run -ti -d --name my-nginx2 -P docker.io/nginx
589237ceec9d5d1de045a5395c0d4b519acf54e8c09afb07af49de1b06d71059
[root@docker-test ~]# docker ps
CONTAINER ID        IMAGE               COMMAND                  CREATED              STATUS              PORTS                   NAMES
589237ceec9d        docker.io/nginx     "nginx -g 'daemon ..."   6 seconds ago        Up 5 seconds        0.0.0.0:32770->80/tcp   my-nginx2
2218c7d88ccc        docker.io/nginx     "nginx -g 'daemon ..."   About a minute ago   Up About a minute   0.0.0.0:8088->80/tcp    my-nginx

由上面可知:
容器my-nginx启动时使用了-p,选择宿主机具体的8088端口映射到容器内部的80端口上了,访问http://localhost/8088即可
容器my-nginx2启动时使用了-P,选择宿主机的一个随机端口映射到容器内部的80端口上了,这里随机端口是32770,访问http://localhost/32770即可

2)启动创建时,绑定外部的ip和端口(宿主机ip是192.168.10.214)

[root@docker-test ~]# docker run -ti -d --name my-nginx3 -p 127.0.0.1:8888:80 docker.io/nginx  
debca5ec7dbb770ca307b06309b0e24b81b6bf689cb11474ec1ba187f4d7802c
[root@docker-test ~]# docker run -ti -d --name my-nginx4 -p 192.168.10.214:9999:80 docker.io/nginx               
ba72a93196f7e55020105b90a51d2203f9cc4d09882e7848ff72f9c43d81852a
[root@docker-test ~]# docker ps
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                         NAMES
ba72a93196f7        docker.io/nginx     "nginx -g 'daemon ..."   2 seconds ago       Up 1 second         192.168.10.214:9999->80/tcp   my-nginx4
debca5ec7dbb        docker.io/nginx     "nginx -g 'daemon ..."   3 minutes ago       Up 3 minutes        127.0.0.1:8888->80/tcp        my-nginx3

由上面可知:
容器my-nginx3绑定的宿主机外部ip是127.0.0.1,端口是8888,则访问http://127.0.0.1:8888或http://localhost:8888都可以,访问http://192.168.10.214:8888就会拒绝!
容器my-nginx4绑定的宿主机外部ip是192.168.10.214,端口是9999,则访问http://192.168.10.214:9999就可以,访问http://127.0.0.1:9999或http://localhost:9999就会拒绝!

3)容器启动时可以指定通信协议,比如tcp、udp

[root@docker-test ~]# docker run -ti -d --name my-nginx5 -p 8099:80/tcp docker.io/nginx
c08eb29e3c0a46386319b475cc95245ccfbf106ed80b1f75d104f8f05d0d0b3e
[root@docker-test ~]# docker run -ti -d --name my-nginx6 -p 192.168.10.214:8077:80/udp docker.io/nginx 
992a48cbd3ef0e568b45c164c22a00389622c2b49e77f936bc0f980718590d5b
[root@docker-test ~]# docker ps
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                                 NAMES
992a48cbd3ef        docker.io/nginx     "nginx -g 'daemon ..."   3 seconds ago       Up 2 seconds        80/tcp, 192.168.10.214:8077->80/udp   my-nginx6
c08eb29e3c0a        docker.io/nginx     "nginx -g 'daemon ..."   53 seconds ago      Up 51 seconds       0.0.0.0:8099->80/tcp                  my-nginx5

4)查看容器绑定和映射的端口及Ip地址

[root@docker-test ~]# docker port my-nginx5
80/tcp -> 0.0.0.0:8099
[root@docker-test ~]# docker inspect my-nginx5|grep IPAddress
            "SecondaryIPAddresses": null,
            "IPAddress": "172.17.0.6",
                    "IPAddress": "172.17.0.6",

5)容器启动绑定多IP和端口(跟多个-p)

[root@docker-test ~]# docker run -ti -d --name my-nginx8 -p 192.168.10.214:7777:80 -p 127.0.0.1:7788:80 docker.io/nginx 
0e86be91026d1601b77b52c346c44a31512138cedc7f21451e996dd2e75d014d
[root@docker-test ~]# docker ps
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                                                 NAMES
0e86be91026d        docker.io/nginx     "nginx -g 'daemon ..."   17 seconds ago      Up 15 seconds       127.0.0.1:7788->80/tcp, 192.168.10.214:7777->80/tcp   my-nginx8

6)容器除了在启动时添加端口映射关系,还可以通过宿主机的iptables进行nat转发,将宿主机的端口映射到容器的内部端口上这种方式适用于容器启动时没有指定端口映射的情况!

[root@docker-test ~]# docker run -ti -d --name my-nginx9 docker.io/nginx
990752e39d75b977cbff5a944247366662211ce43d16843a452a5697ddded12f
[root@docker-test ~]# docker ps
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS            NAMES
990752e39d75        docker.io/nginx     "nginx -g 'daemon ..."   2 seconds ago       Up 1 second         80/tcp           my-nginx9

这个时候,由于容器my-nginx9在启动时没有指定其内部的80端口映射到宿主机的端口上,所以默认是没法访问的!
现在通过宿主机的iptables进行net转发

首先获得容器的ip地址
[root@docker-test ~]# docker inspect my-nginx9|grep IPAddress
            "SecondaryIPAddresses": null,
            "IPAddress": "172.17.0.9",
                    "IPAddress": "172.17.0.9",

[root@docker-test ~]# ping 172.17.0.9
PING 172.17.0.9 (172.17.0.9) 56(84) bytes of data.
64 bytes from 172.17.0.9: icmp_seq=1 ttl=64 time=0.105 ms
64 bytes from 172.17.0.9: icmp_seq=2 ttl=64 time=0.061 ms
.....

[root@docker-test ~]# telnet 172.17.0.9 80 
Trying 172.17.0.9...
Connected to 172.17.0.9.
Escape character is '^]'


centos7下部署iptables环境纪录(关闭默认的firewalle)
参考:http://www.cnblogs.com/kevingrace/p/5799210.html

将容器的80端口映射到dockers宿主机的9998端口
[root@docker-test ~]# iptables -t nat -A PREROUTING -p tcp -m tcp --dport 9998 -j DNAT --to-destination 172.17.0.9:80
[root@docker-test ~]# iptables -t nat -A POSTROUTING -d 172.17.0.9/32 -p tcp -m tcp --sport 80 -j SNAT --to-source 192.16.10.214
[root@docker-test ~]# iptables -t filter -A INPUT -p tcp -m state --state NEW -m tcp --dport 9998 -j ACCEPT

保存以上iptables规则
[root@docker-test ~]# iptables-save > /etc/sysconfig/iptables

查看/etc/sysconfig/iptables文件,注意下面两行有关icmp-host-prohibited的设置一定要注释掉!否则nat转发会失败!
[root@docker-test ~]# cat /etc/sysconfig/iptables
# Generated by iptables-save v1.4.21 on Fri Aug 10 11:13:57 2018
*nat
:PREROUTING ACCEPT [32:1280]
:INPUT ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
:POSTROUTING ACCEPT [0:0]
-A PREROUTING -p tcp -m tcp --dport 9998 -j DNAT --to-destination 172.17.0.9:80
-A POSTROUTING -d 172.17.0.9/32 -p tcp -m tcp --sport 80 -j SNAT --to-source 192.16.10.214
COMMIT
# Completed on Fri Aug 10 11:13:57 2018
# Generated by iptables-save v1.4.21 on Fri Aug 10 11:13:57 2018
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [50:5056]
-A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
-A INPUT -p icmp -j ACCEPT
-A INPUT -i lo -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 22 -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 9998 -j ACCEPT
#-A INPUT -j REJECT --reject-with icmp-host-prohibited
#-A FORWARD -j REJECT --reject-with icmp-host-prohibited
COMMIT
# Completed on Fri Aug 10 11:13:57 2018

最后重启iptbales服务
[root@docker-test ~]# systemctl restart iptables

查看iptables规则
[root@docker-test ~]# iptables -L
Chain INPUT (policy ACCEPT)
target     prot opt source               destination         
ACCEPT     all  --  anywhere             anywhere             state RELATED,ESTABLISHED
ACCEPT     icmp --  anywhere             anywhere            
ACCEPT     all  --  anywhere             anywhere            
ACCEPT     tcp  --  anywhere             anywhere             state NEW tcp dpt:ssh
ACCEPT     tcp  --  anywhere             anywhere             state NEW tcp dpt:distinct32

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination         

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination        

[root@docker-test ~]# iptables -L -t nat
Chain PREROUTING (policy ACCEPT)
target     prot opt source               destination         
DNAT       tcp  --  anywhere             anywhere             tcp dpt:distinct32 to:172.17.0.9:80

Chain INPUT (policy ACCEPT)
target     prot opt source               destination         

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination         

Chain POSTROUTING (policy ACCEPT)
target     prot opt source               destination         
SNAT       tcp  --  anywhere             172.17.0.9           tcp spt:http to:192.16.10.214

然后访问http://192.168.10.214:9998/,就能转发访问到my-nginx9容器的80端口了!!! 

一次性删除所有容器,包括正在运行的容器

[root@docker-test ~]# docker rm -f `docker ps -a -q`
990752e39d75
0e86be91026d
ff2bc46a8ee4
c08eb29e3c0a
ba72a93196f7
debca5ec7dbb
589237ceec9d
2218c7d88ccc
[root@docker-test ~]# docker ps -a
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES

如果启动docker 容器时,有如下报错:
/usr/bin/docker-current: Error response from daemon: driver failed programming external connectivity on endpoint my-nginx (db5a0edac68d1ea7ccaa3a1e0db31ebdf278076ef4851ee4250221af6167f9ac): (iptables failed: iptables --wait -t nat -A DOCKER -p tcp -d 0/0 --dport 8088 -j DNAT --to-destination 172.17.0.2:80 ! -i docker0: iptables: No chain/target/match by that name.

解决办法

1)不需要关闭防火墙
2)重启docker服务:systemctl restart docker
3)docker服务重启后,所有容器都会关闭,应立即批量启动全部容器:docker start `docker ps -a -q`
   启动的容器也会包括上面报错的容器,重启docker后,该容器就能正常启动和使用了!

============问题:  Docker 端口映射到宿主机后, 外部无法访问对应宿主机端口==============

创建docker容器的时候,做了端口映射到宿主机, 防火墙已关闭, 但是外部始终无法访问宿主机端口?
这种情况基本就是因为宿主机没有开启ip转发功能,从而导致外部网络访问宿主机对应端口是没能转发到 Docker Container 所对应的端口上。

解决办法:
Linux 发行版默认情况下是不开启 ip 转发功能的。这是一个好的做法,因为大多数人是用不到 ip 转发的,但是如果架设一个 Linux 路由或者VPN服务我们就需要开启该服务了。

在 Linux 中开启 ip 转发的内核参数为:net.ipv4.ip_forward,查看是否开启 ip转发:
# cat /proc/sys/net/ipv4/ip_forward           // 0:未开启,1:已开启

==============================
打开ip转发功能, 下面两种方法都是临时打开ip转发功能!
# echo 1 > /proc/sys/net/ipv4/ip_forward
# sysctl -w net.ipv4.ip_forward=1

==============================
永久生效的ip转发
# vim /etc/sysctl.conf
net.ipv4.ip_forward = 1

# sysctl -p /etc/sysctl.conf      // 立即生效

Linux 系统中也可以通过重启网卡来立即生效 (修改sysctl.conf文件后的生效)
# service network restart                  //CentOS 6
# systemctl restart network              //CentOS 7
posted @ 2018-08-10 11:30  散尽浮华  阅读(69328)  评论(5编辑  收藏