本文讨论同一宿主机下不同docker容器间通信的解决方案，比如宿主机下PHP的web服务容器需要连接mysql容器就会用到接下来说的方法。
正常情况下，我们安装完docker会创建一个默认网桥docker0
#手动安装brctl命令
[root@new2 dockerfile]# brctl show
bridge name bridge id STP enabled interfaces
br-72a0e7df683d 8000.0242ea904416 no
br-8c32615c1dea 8000.0242723a4063 no vethe3eb576
vethfa75006
docker0 8000.0242e12e8e06 no
同是docker安装后会默认创建三个网络：bridge/host/name，其中bridge模式是docker默认使用的网络
[root@new2 dockerfile]# docker network ls NETWORK ID NAME DRIVER SCOPE 350b170c0117 bridge bridge local 8610e4eb9359 host host local f8d2652c4dec none null local Docker四种网络工作模式: #host：容器将不会虚拟出自己的网卡，配置自己的IP等，而是使用宿主机的IP和端口，使用--net=host指定; #Container：创建的容器不会创建自己的网卡，配置自己的IP，而是和一个指定的容器共享IP、端口范围，使用 --net=container:NAME_or_ID指定; #None：关闭了容器的网络功能，使用--net=none指定; #Bridge：为每一个容器分配、设置IP等，并将容器连接到一个docker0虚拟网桥，通过docker0网桥以及Iptables nat表配置与宿主机通信，使用--net=bridge指定，默认设置;
docker容器间通信可以使用link和bridge网桥，不过link后期可能要被移除，官方也不推荐使用。
https://docs.docker.com/network/links/
这里主要说自定义bridge网络来实现容器间通信
docker1.10版本开始内嵌一个DNS server，方便容器间通过“”容器名“通信。使用默认的bridge网络，不能通过DNS server实现容器名通信，不过我们可以使用自定义bridge网络来实现。
首先看下使用默认bridge网桥配置的容器通信情况：
#这里指定80端口，因为镜像创建时，已指定需要通过80端口访问容器 [root@new2 ~]# docker run -d -p 80 --name="centos_default_bridge" mycentos_from_dockerfile:v2 /bin/bash 703d2d4cb2cec56f4c539fa2dbe687c0b91be8cd2c50de76086bdc665a185366 [root@new2 ~]# docker run -d -p 80 --name="centos_default_bridge" mycentos_from_dockerfile:v2 /bin/bash 8103a5b3ab458de4cb2c94faae407f1db3cea20050611e0847492b2605c1ee33 #看下centos_default_bridge2配置，可见其IP地址为：172.17.0.2 [root@new2 ~]# docker inspect centos_default_bridge2 [ { "Id": "8103a5b3ab458de4cb2c94faae407f1db3cea20050611e0847492b2605c1ee33", "Created": "2020-07-11T14:43:09.949852828Z", "Path": "/bin/bash", "Args": [], "State": { "Status": "running", "Running": true, "Paused": false, "Restarting": false, "OOMKilled": false, "Dead": false, "Pid": 27461, "ExitCode": 0, "Error": "", "StartedAt": "2020-07-11T14:43:10.231446816Z", "FinishedAt": "0001-01-01T00:00:00Z" }, "Image": "sha256:4b1edd50a106bb6dfec2cd161e39f9874a215ee064364967aac80f1cc50082bb", "ResolvConfPath": "/var/lib/docker/containers/8103a5b3ab458de4cb2c94faae407f1db3cea20050611e0847492b2605c1ee33/resolv.conf", "HostnamePath": "/var/lib/docker/containers/8103a5b3ab458de4cb2c94faae407f1db3cea20050611e0847492b2605c1ee33/hostname", "HostsPath": "/var/lib/docker/containers/8103a5b3ab458de4cb2c94faae407f1db3cea20050611e0847492b2605c1ee33/hosts", "LogPath": "/var/lib/docker/containers/8103a5b3ab458de4cb2c94faae407f1db3cea20050611e0847492b2605c1ee33/8103a5b3ab458de4cb2c94faae407f1db3cea20050611e0847492b2605c1ee33-json.log", "Name": "/centos_default_bridge2", "RestartCount": 0, "Driver": "overlay2", "Platform": "linux", "MountLabel": "", "ProcessLabel": "", "AppArmorProfile": "", "ExecIDs": null, "HostConfig": { "Binds": null, "ContainerIDFile": "", "LogConfig": { "Type": "json-file", "Config": {} }, "NetworkMode": "default", "PortBindings": { "80/tcp": [ { "HostIp": "", "HostPort": "" } ] }, "RestartPolicy": { "Name": "no", "MaximumRetryCount": 0 }, "AutoRemove": false, "VolumeDriver": "", "VolumesFrom": null, "CapAdd": null, "CapDrop": null, "Capabilities": null, "Dns": [], "DnsOptions": [], "DnsSearch": [], "ExtraHosts": null, "GroupAdd": null, "IpcMode": "private", "Cgroup": "", "Links": null, "OomScoreAdj": 0, "PidMode": "", "Privileged": false, "PublishAllPorts": false, "ReadonlyRootfs": false, "SecurityOpt": null, "UTSMode": "", "UsernsMode": "", "ShmSize": 67108864, "Runtime": "runc", "ConsoleSize": [ 0, 0 ], "Isolation": "", "CpuShares": 0, "Memory": 0, "NanoCpus": 0, "CgroupParent": "", "BlkioWeight": 0, "BlkioWeightDevice": [], "BlkioDeviceReadBps": null, "BlkioDeviceWriteBps": null, "BlkioDeviceReadIOps": null, "BlkioDeviceWriteIOps": null, "CpuPeriod": 0, "CpuQuota": 0, "CpuRealtimePeriod": 0, "CpuRealtimeRuntime": 0, "CpusetCpus": "", "CpusetMems": "", "Devices": [], "DeviceCgroupRules": null, "DeviceRequests": null, "KernelMemory": 0, "KernelMemoryTCP": 0, "MemoryReservation": 0, "MemorySwap": 0, "MemorySwappiness": null, "OomKillDisable": false, "PidsLimit": null, "Ulimits": null, "CpuCount": 0, "CpuPercent": 0, "IOMaximumIOps": 0, "IOMaximumBandwidth": 0, "MaskedPaths": [ "/proc/asound", "/proc/acpi", "/proc/kcore", "/proc/keys", "/proc/latency_stats", "/proc/timer_list", "/proc/timer_stats", "/proc/sched_debug", "/proc/scsi", "/sys/firmware" ], "ReadonlyPaths": [ "/proc/bus", "/proc/fs", "/proc/irq", "/proc/sys", "/proc/sysrq-trigger" ] }, "GraphDriver": { "Data": { "LowerDir": "/var/lib/docker/overlay2/63be01a957afade10e8fa521537f9064b7912b0b2467974b17176ca8ea0d0c0b-init/diff:/var/lib/docker/overlay2/e26f0878029f868adb8ad43aa3081cbfce8e9d75f53da932f4d2ac55edc416f1/diff:/var/lib/docker/overlay2/a8ed9e8b220f02b57c8894633ffdd3260328dc8635a56c6c47dd75ae62fbd820/diff:/var/lib/docker/overlay2/236027395c3ba490761ea3de6d09be437ccad05161ce70cdb6122de516903110/diff:/var/lib/docker/overlay2/5d3a4eeea4718541893c89d08bae72ca2e74a03d683602a981d2dccd4f0efcfe/diff", "MergedDir": "/var/lib/docker/overlay2/63be01a957afade10e8fa521537f9064b7912b0b2467974b17176ca8ea0d0c0b/merged", "UpperDir": "/var/lib/docker/overlay2/63be01a957afade10e8fa521537f9064b7912b0b2467974b17176ca8ea0d0c0b/diff", "WorkDir": "/var/lib/docker/overlay2/63be01a957afade10e8fa521537f9064b7912b0b2467974b17176ca8ea0d0c0b/work" }, "Name": "overlay2" }, "Mounts": [], "Config": { "Hostname": "8103a5b3ab45", "Domainname": "", "User": "", "AttachStdin": false, "AttachStdout": false, "AttachStderr": false, "ExposedPorts": { "80/tcp": {} }, "Tty": true, "OpenStdin": true, "StdinOnce": false, "Env": [ "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin", "DEBIAN_FRONTEND=noninteractive", "TEST_VERSION=1.0.1", "POSITION=Guangzhou.Guangdong" ], "Cmd": [ "/bin/bash" ], "Image": "mycentos_from_dockerfile:v2", "Volumes": null, "WorkingDir": "", "Entrypoint": null, "OnBuild": null, "Labels": {} }, "NetworkSettings": { "Bridge": "", "SandboxID": "1fa15de81e77b2f1269f14a1c44eb5271963cdfd4984db903492b1118e582be4", "HairpinMode": false, "LinkLocalIPv6Address": "", "LinkLocalIPv6PrefixLen": 0, "Ports": { "80/tcp": [ { "HostIp": "0.0.0.0", "HostPort": "32776" } ] }, "SandboxKey": "/var/run/docker/netns/1fa15de81e77", "SecondaryIPAddresses": null, "SecondaryIPv6Addresses": null, "EndpointID": "58d50f77368ac19641dbf5c191761d090af674852ab658c189ee4a7951e5012e", "Gateway": "172.17.0.1", "GlobalIPv6Address": "", "GlobalIPv6PrefixLen": 0, "IPAddress": "172.17.0.2", "IPPrefixLen": 16, "IPv6Gateway": "", "MacAddress": "02:42:ac:11:00:02", "Networks": { "bridge": { "IPAMConfig": null, "Links": null, "Aliases": null, "NetworkID": "350b170c01176d38b5bb543c9305a2d90fbcc739e3a8619bd7691599bf491fc2", "EndpointID": "58d50f77368ac19641dbf5c191761d090af674852ab658c189ee4a7951e5012e", "Gateway": "172.17.0.1", "IPAddress": "172.17.0.2", "IPPrefixLen": 16, "IPv6Gateway": "", "GlobalIPv6Address": "", "GlobalIPv6PrefixLen": 0, "MacAddress": "02:42:ac:11:00:02", "DriverOpts": null } } } } ] #进入centos_default_bridge容器 [root@new2 ~]# docker exec -it centos_default_bridge /bin/bash #在centos_default_bridge容器通过IP来ping容器centos_default_bridge2网络畅通 root@703d2d4cb2ce:/# 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=0.048 ms 64 bytes from 172.17.0.2: icmp_seq=2 ttl=64 time=0.052 ms 64 bytes from 172.17.0.2: icmp_seq=3 ttl=64 time=0.056 ms 64 bytes from 172.17.0.2: icmp_seq=4 ttl=64 time=0.054 ms ^C --- 172.17.0.2 ping statistics --- 4 packets transmitted, 4 received, 0% packet loss, time 2999ms rtt min/avg/max/mdev = 0.048/0.052/0.056/0.007 ms #切换成centos_default_bridge2来ping，网络不通 root@703d2d4cb2ce:/# ping centos_default_bridge2 ping: unknown host centos_default_bridge2
下面新建一个自定义网络centos_expose_bridge，新增两个容器指定使用自定义网络配置
[root@new2 dockerfile]# docker network create -d bridge centos_expose_bridge [root@new2 dockerfile]# docker network ls NETWORK ID NAME DRIVER SCOPE 350b170c0117 bridge bridge local 8c32615c1dea centos_expose_bridge bridge local 72a0e7df683d dnmp_default bridge local 8610e4eb9359 host host local f8d2652c4dec none null local #基于同一镜像创建指定网络的容器 [root@new2 dockerfile]# docker run -d --name centos_bridge --network centos_expose_bridge mycentos:v2 /bin/bash [root@new2 dockerfile]# docker run -d --name centos_bridge --network centos_expose_bridge mycentos:v2 /bin/bash [root@new2 dockerfile]# docker network inspect centos_expose_bridge [ { "Name": "centos_expose_bridge", "Id": "8c32615c1dea401220d12dfd7720171f32f1bacc057977c560cac27c91725738", "Created": "2020-07-11T17:18:21.824462131+08:00", "Scope": "local", "Driver": "bridge", "EnableIPv6": false, "IPAM": { "Driver": "default", "Options": {}, "Config": [ { "Subnet": "172.19.0.0/16", "Gateway": "172.19.0.1" } ] }, "Internal": false, "Attachable": false, "Ingress": false, "ConfigFrom": { "Network": "" }, "ConfigOnly": false, "Containers": { "37d696620875695a73936b39c62fd3eac191683f89f5da701a11f4ea9e37b45e": { "Name": "docker_expose", "EndpointID": "d5525bf34381dc4d6b77649e1e28d61c90af86f08855c5830f4907e53bf74fc1", "MacAddress": "02:42:ac:13:00:02", "IPv4Address": "172.19.0.2/16", "IPv6Address": "" }, "94c0b5178358def497bdad5d74ca609c2456309feeb111979217d3944d1c6ba2": { "Name": "docker_expose2", "EndpointID": "3ef1e63cbc1bbacc97b2375d81d83564a4a85c38fc72d12767181ba71031a652", "MacAddress": "02:42:ac:13:00:03", "IPv4Address": "172.19.0.3/16", "IPv6Address": "" } }, "Options": {}, "Labels": {} } ]
#进入其中centos_expose容器ping一下centos_expose2容器，可见是可以直ping容器名的 [root@new2 ~]# docker exec -it docker_expose /bin/bash root@37d696620875:/# ping docker_expose2 PING docker_expose2 (172.19.0.3) 56(84) bytes of data. 64 bytes from docker_expose2.centos_expose_bridge (172.19.0.3): icmp_seq=1 ttl=64 time=0.042 ms 64 bytes from docker_expose2.centos_expose_bridge (172.19.0.3): icmp_seq=2 ttl=64 time=0.054 ms #容器的hosts文件并没有centos_expose2映射配置 root@37d696620875:/# cat /etc/hosts 127.0.0.1 localhost ::1 localhost ip6-localhost ip6-loopback fe00::0 ip6-localnet ff00::0 ip6-mcastprefix ff02::1 ip6-allnodes ff02::2 ip6-allrouters 172.19.0.2 37d696620875 #再看下DNS服务解析配置，可见指向127.0.0.11地址，使用默认bridge网络的容器在resolv.conf不会出现该地址 root@37d696620875:/# cat /etc/resolv.conf nameserver 127.0.0.11 options timeout:1 rotate ndots:0