Docker网络详解

Docker网络详解

Docker0网络

准备工作：清空所有的容器，清空所有的镜像

docker rm -f $(docker ps -a -q)             # 删除所有容器
docker rmi -f $(docker images -qa)          # 删除全部镜像

本地干净的网络

[root@kuangshenlinux ~]# ip addr

# 本地回环网络
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
       
# 网卡地址 wifi
2: enp0s3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 08:00:27:e0:aa:73 brd ff:ff:ff:ff:ff:ff
    inet 192.168.0.111/24 brd 192.168.0.255 scope global noprefixroute enp0s3
       valid_lft forever preferred_lft forever
    inet6 fe80::3202:526:12cb:70ec/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
       
# docker 0 ，docker创建的网络
3: docker0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default 
    link/ether 02:42:f8:9d:a8:42 brd ff:ff:ff:ff:ff:ff
    inet 172.17.0.1/16 brd 172.17.255.255 scope global docker0
       valid_lft forever preferred_lft forever

1、微服务这么多，访问怎么解决？ （容器名）

2、docker每启动一个容器，就会给他分配一个ip。docker0是docker默认给的。我们不指定网络的情况下，创建容器都在docker0中，未来开发，我们要自定义网络。

[root@kuangshenlinux ~]# docker run -itd --name web01 centos
Unable to find image 'centos:latest' locally
latest: Pulling from library/centos
a1d0c7532777: Already exists 
Digest: sha256:a27fd8080b517143cbbbab9dfb7c8571c40d67d534bbdee55bd6c473f432b177
Status: Downloaded newer image for centos:latest
53231c3adf0423ed2d0577ead987507c12978416349a51445d663c9536c9b4ff

# docker每启动一个容器，就会给他分配一个ip。这个ip就是归docker0 管理
[root@kuangshenlinux ~]# docker exec -it web01 ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
4: eth0@if5: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default 
    link/ether 02:42:ac:11:00:02 brd ff:ff:ff:ff:ff:ff link-netnsid 0
    inet 172.17.0.2/16 brd 172.17.255.255 scope global eth0
       valid_lft forever preferred_lft forever

# 容器外本地可以ping到容器里面
[root@kuangshenlinux ~]# ping 172.17.0.2
PING 172.17.0.2 (172.17.0.2) 56(84) bytes of data.
64 bytes from 172.17.0.2: icmp_seq=1 ttl=64 time=0.058 ms

分析原理

1、本来有三个网络，启动容器后，多了一个，这个网络和容器内部的网络是配对的。

# 再次启动一个容器查看
[root@kuangshenlinux ~]# docker exec -it web02 ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
6: eth0@if7: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default 
    link/ether 02:42:ac:11:00:03 brd ff:ff:ff:ff:ff:ff link-netnsid 0
    inet 172.17.0.3/16 brd 172.17.255.255 scope global eth0
       valid_lft forever preferred_lft forever
[root@kuangshenlinux ~]# ip addr
....
3: docker0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default 
    link/ether 02:42:f8:9d:a8:42 brd ff:ff:ff:ff:ff:ff
    inet 172.17.0.1/16 brd 172.17.255.255 scope global docker0
       valid_lft forever preferred_lft forever
    inet6 fe80::42:f8ff:fe9d:a842/64 scope link 
       valid_lft forever preferred_lft forever
5: veth3b4847e@if4: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master docker0 state UP group default 
    link/ether 0e:58:71:93:42:18 brd ff:ff:ff:ff:ff:ff link-netnsid 0
    inet6 fe80::c58:71ff:fe93:4218/64 scope link 
       valid_lft forever preferred_lft forever
7: veth13568df@if6: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master docker0 state UP group default 
    link/ether 9a:3c:71:70:e2:a0 brd ff:ff:ff:ff:ff:ff link-netnsid 1
    inet6 fe80::983c:71ff:fe70:e2a0/64 scope link 
       valid_lft forever preferred_lft forever


# 总结观察：
1、web1 -- linux 主机     5: veth3b4847e@if4:    4: eth0@if5
2、web2 -- linux 主机     7: veth13568df@if6:    6: eth0@if7

# 只要启动一个容器，默认就会分配一对网卡。
# 虚拟接口 # veth-pair 就是一对的虚拟设备接口，它都是成对出现的。一端连着协议栈，一端彼此相连着。
# 就好比一个桥梁，可以连通容器内外。

# 测试容器之间的访问，ip访问没有问题
[root@kuangshenlinux ~]# docker exec -it web02 ping 172.17.0.2
PING 172.17.0.2 (172.17.0.2) 56(84) bytes of data.
64 bytes from 172.17.0.2: icmp_seq=1 ttl=64 time=0.058 ms
64 bytes from 172.17.0.2: icmp_seq=2 ttl=64 time=0.064 ms
^C
--- 172.17.0.2 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1001ms
rtt min/avg/max/mdev = 0.058/0.061/0.064/0.