容器技术｜Docker三剑客之docker-swarm

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互联网集市收集整理的这篇技术教程文章主要介绍了容器技术｜Docker三剑客之docker-swarm，小编现在分享给大家，供广大互联网技能从业者学习和参考。文章包含20761字，纯文字阅读大概需要30分钟。

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接之前的文章：

容器技术｜Docker三剑客之docker-machine

容器技术｜Docker三剑客之Compose

docker-swarm简介

Swarm是Docker官方提供的一款集群管理工具，其主要作用是把若干台Docker主机抽象为一个整体，并且通过一个入口统一管理这些Docker主机上的各种Docker资源。Swarm和Kubernetes比较类似，但是更加轻，具有的功能也较kubernetes更少一些。
swarm集群提供给用户管理集群内所有容器的操作接口与使用一台Docker主机基本相同。
Swarm集群目前有两个版本：V1、V2

1、Swarm v1它是master-slave架构。需要通过服务发现来选举出管理节点，其它各个节点通过运行agent来接受管理节点的统一管理
2、Swarm v2集群是自动通过Raft协议分布式选举出管理节点，不需要配置发现服务，从而避免发现服务的单点故障问题。且它自带了DNS负载均衡和对外部负载均衡机制的支持

Swarm的基本架构如下图所示

Swarm一些概念说明

• 1、Swarm
  使用swarmkit嵌入docker Engine中的集群管理和编排功能。docker容器初始化启动的一种模式

• 2、Node
  节点，是一个已加入到docker swarm集群中的一个容器实例。

• 3、Service
  服务主要是在工作节点上执行任务，创建服务时，需要指定容器的镜像。

• 4、Task
  任务是在容器中执行的命令

Swarm 工作方式

• 1、节点

• 2、服务、任务、容器

• 3、任务与调度

• 4、服务副本与全局服务

Swarm 调度策略

Swarm在scheduler节点（leader 节点）运行容器的时候，会根据指定的策略来计算最适合运行容器的节点，目前支持的策略有：spread, binpack, random.
1）Random
顾名思义，就是随机选择一个 Node 来运行容器，一般用作调试用，spread 和 binpack 策略会根据各个节点的可用的 CPU, RAM 以及正在运行的容器的数量来计算应该运行容器的节点。
2）Spread
在同等条件下，Spread 策略会选择运行容器最少的那台节点来运行新的容器，binpack 策略会选择运行容器最集中的那台机器来运行新的节点。使用 Spread 策略会使得容器会均衡的分布在集群中的各个节点上运行，一旦一个节点挂掉了只会损失少部分的容器。
3）Binpack
Binpack 策略最大化的避免容器碎片化，就是说 binpack 策略尽可能的把还未使用的节点留给需要更大空间的容器运行，尽可能的把容器运行在一个节点上面。

Swarm Cluster模式的特性

1）批量创建服务
建立容器之前先创建一个 overlay 的网络，用来保证在不同主机上的容器网络互通的网络模式
2）强大的集群的容错性
当容器副本中的其中某一个或某几个节点宕机后，cluster 会根据自己的服务注册发现机制，以及之前设定的值–replicas n，在集群中剩余的空闲节点上，重新拉起容器副本。整个副本迁移的过程无需人工干预，迁移后原本的集群的 load balance 依旧好使！
不难看出，docker service 其实不仅仅是批量启动服务这么简单，而是在集群中定义了一种状态。Cluster 会持续检测服务的健康状态并维护集群的高可用性。
3）服务节点的可扩展性
Swarm Cluster不光只是提供了优秀的高可用性，同时也提供了节点弹性扩展或缩减的功能。当容器组想动态扩展时，只需通过 scale参数即可复制出新的副本出来。仔细观察的话，可以发现所有扩展出来的容器副本都 run 在原先的节点下面，如果有需求想在每台节点上都 run 一个相同的副本，方法其实很简单，只需要在命令中将”–replicas n”更换成”–mode=global”即可！复制服务（–replicas n）将一系列复制任务分发至各节点当中，具体取决于您所需要的设置状态，例如“–replicas 3”。全局服务（–mode=global）适用于集群内全部可用节点上的服务任务，例如“–mode global”。如果大家在 Swarm 集群中设有 7 台 Docker 节点，则全部节点之上都将存在对应容器。
4）调度机制
所谓的调度其主要功能是 cluster 的 server 端去选择在哪个服务器节点上创建并启动一个容器实例的动作。它是由一个装箱算法和过滤器组合而成。每次通过过滤器（constraint）启动容器的时候，swarm cluster 都会调用调度机制筛选出匹配约束条件的服务器，并在这上面运行容器。

Swarm cluster的创建过程

• 1）发现 Docker 集群中的各个节点，收集节点状态、角色信息，并监视节点状态的变化

• 2）初始化内部调度（scheduler）模块

• 3）创建并启动 API 监听服务模块
  一旦创建好这个 cluster，就可以用命令 docker service 批量对集群内的容器进行操作，在启动容器后，docker 会根据当前每个 swarm 节点的负载判断，在负载最优的节点运行这个 task 任务，用”docker service ls” 和”docker service ps + taskID”可以看到任务运行在哪个节点上。容器启动后，有时需要等待一段时间才能完成容器创建。

Swarm命令行说明

docker?swarm：集群管理
init??????????#初始化集群
join??????????#将节点加入集群
join-token????#管理加入令牌
leave?????????#从集群中删除某个节点，强制删除加参数--force?
update????????#更新集群
unlock????????#解锁集群

docker?node：节点管理，
demote??????#将集群中一个或多个节点降级
inspect?????#显示一个或多个节点的详细信息
ls??????????#列出集群中的节点
promote?????#将一个或多个节点提升为管理节点
rm??????????#从集群中删除停止的节点，--force强制删除参数
ps??????????#列出一个或多个节点上运行的任务
update??????#更新节点

docker?service：服务管理，
create??????#创建一个新的服务
inspect?????#列出一个或多个服务的详细信息
ps??????????#列出一个或多个服务中的任务信息
ls??????????#列出服务
rm??????????#删除一个或多个服务
scale???????#扩展一个或多个服务
update??????#更新服务

docker?stack/deploy：试验特性，用于多应用部署

安装布署swarm集群服务

1、修改主机名，配置hosts文件

[root@manager?~]#?cat?>>/etc/hosts<<EOF
192.168.22.177?manager
192.168.22.175?node1
192.168.22.178?node2
EOF
[root@manager?~]#?tail?-3?/etc/hosts
192.168.22.177?manager
192.168.22.175?node1
192.168.22.178?node2
[root@manager?~]#?ping?node1
PING?node1?(192.168.22.175)?56(84)?bytes?of?data.
64?bytes?from?node1?(192.168.22.175):?icmp_seq=1?ttl=64?time=3.64?ms
64?bytes?from?node1?(192.168.22.175):?icmp_seq=2?ttl=64?time=1.64?ms
^C
---?node1?ping?statistics?---
2?packets?transmitted,?2?received,?0%?packet?loss,?time?1006ms
rtt?min/avg/max/mdev?=?1.648/2.644/3.641/0.997?ms
[root@manager?~]#?ping?node2
PING?node2?(192.168.22.178)?56(84)?bytes?of?data.
64?bytes?from?node2?(192.168.22.178):?icmp_seq=1?ttl=64?time=9.70?ms
64?bytes?from?node2?(192.168.22.178):?icmp_seq=2?ttl=64?time=1.95?ms
^C
---?node2?ping?statistics?---
2?packets?transmitted,?2?received,?0%?packet?loss,?time?1003ms
rtt?min/avg/max/mdev?=?1.951/5.826/9.701/3.875?ms
#node1?node2配置同上一致即可

2、安装docker环境

具体安装过程参考前面的文章

配置docker

[root@manager?~]#?vim?/etc/sysconfig/docker
#?/etc/sysconfig/docker

#?Modify?these?options?if?you?want?to?change?the?way?the?docker?daemon?runs
OPTIONS='-H?0.0.0.0:2375?-H?unix:///var/run/docker.sock?--selinux-enabled?--log-driver=journald?--signature-verification=false'
#所有节点加上上面标记的部分，开启2375端口

[root@manager?~]#?systemctl?restart?docker
[root@manager?~]#?ps?-ef|grep?docker
root??????11981??????1??1?10:55??????????00:00:00?/usr/bin/dockerd-current?--add-runtime?docker-runc=/usr/libexec/docker/docker-runc-current?--default-runtime=docker-runc?--exec-opt?native.cgroupdriver=systemd?--userland-proxy-path=/usr/libexec/docker/docker-proxy-current?--init-path=/usr/libexec/docker/docker-init-current?--seccomp-profile=/etc/docker/seccomp.json?-H?0.0.0.0:2375?-H?unix:///var/run/docker.sock?--selinux-enabled?--log-driver=journald?--signature-verification=false?--storage-driver?overlay2
root??????11986??11981??0?10:55??????????00:00:00?/usr/bin/docker-containerd-current?-l?unix:///var/run/docker/libcontainerd/docker-containerd.sock?--metrics-interval=0?--start-timeout?2m?--state-dir?/var/run/docker/libcontainerd/containerd?--shim?docker-containerd-shim?--runtime?docker-runc?--runtime-args?--systemd-cgroup=true
root??????12076??11823??0?10:55?pts/0????00:00:00?grep?--color=auto?docker
[root@manager?~]#?lsof?-i?:2375
COMMAND?????PID?USER???FD???TYPE?DEVICE?SIZE/OFF?NODE?NAME
dockerd-c?11981?root????5u??IPv6??41829??????0t0??TCP?*:2375?(LISTEN)

3、所有节点下载swarm镜像文件

[root@manager?~]#?docker?pull?swarm
Using?default?tag:?latest
Trying?to?pull?repository?docker.io/library/swarm?...?
latest:?Pulling?from?docker.io/library/swarm
d85c18077b82:?Pull?complete?
1e6bb16f8cb1:?Pull?complete?
85bac13497d7:?Pull?complete?
Digest:?sha256:406022f04a3d0c5ce4dbdb60422f24052c20ab7e6d41ebe5723aa649c3833975
Status:?Downloaded?newer?image?for?docker.io/swarm:latest
[root@manager?~]#?docker?images
REPOSITORY???????TAG??????IMAGE?ID??????CREATED??????SIZE
docker.io/swarm??latest???ff454b4a0e84??12?days?ago??12.7?MB

4、创建swarm并初始化

[root@manager?~]#?docker?swarm?init?--advertise-addr?192.168.22.177
Swarm?initialized:?current?node?(elyfa6h1lx5o2s98une5vas4x)?is?now?a?manager.

To?add?a?worker?to?this?swarm,?run?the?following?command:

????docker?swarm?join?\
????--token?SWMTKN-1-32h92m334z80z270d4duqdc3ysl1oyrjmxe1upyyfjyln12xxa-4gm603mczorxgh6751n5q7jya?\
????192.168.22.177:2377

To?add?a?manager?to?this?swarm,?run?'docker?swarm?join-token?manager'?and?follow?the?instructions.
#执行上面的命令后，当前的服务器就加入到swarm集群中，同时会产生一个唯一的token值，其它节点加入集群时需要用到这个token。
#--advertise-addr?表示swarm集群中其它节点使用后面的IP地址与管理节点通讯，上面也提示了其它节点如何加入集群的命令。

5、查看下当前的信息

[root@manager?~]#?docker?info
Containers:?0
?Running:?0
?Paused:?0
?Stopped:?0
Images:?1
Server?Version:?1.13.1
Storage?Driver:?overlay2
?Backing?Filesystem:?xfs
?Supports?d_type:?true
?Native?Overlay?Diff:?true
Logging?Driver:?journald
Cgroup?Driver:?systemd
Plugins:?
?Volume:?local
?Network:?bridge?host?macvlan?null?overlay
**Swarm:?active
?NodeID:?elyfa6h1lx5o2s98une5vas4x
?Is?Manager:?true
?ClusterID:?vi716cgvw33gzicrfqopasf9p
?Managers:?1
?Nodes:?1
?Orchestration:
??Task?History?Retention?Limit:?5
?Raft:
??Snapshot?Interval:?10000
??Number?of?Old?Snapshots?to?Retain:?0
??Heartbeat?Tick:?1
??Election?Tick:?3
?Dispatcher:
??Heartbeat?Period:?5?seconds
?CA?Configuration:
??Expiry?Duration:?3?months
?Node?Address:?192.168.22.177
?Manager?Addresses:
??192.168.22.177:2377
Runtimes:?docker-runc?runc
Default?Runtime:?docker-runc
Init?Binary:?/usr/libexec/docker/docker-init-current
containerd?version:??(expected:?aa8187dbd3b7ad67d8e5e3a15115d3eef43a7ed1)
runc?version:?e9c345b3f906d5dc5e8100b05ce37073a811c74a?(expected:?9df8b306d01f59d3a8029be411de015b7304dd8f)
init?version:?5b117de7f824f3d3825737cf09581645abbe35d4?(expected:?949e6facb77383876aeff8a6944dde66b3089574)
Security?Options:
?seccomp
??WARNING:?You're?not?using?the?default?seccomp?profile
??Profile:?/etc/docker/seccomp.json
Kernel?Version:?3.10.0-693.el7.x86_64
Operating?System:?CentOS?Linux?7?(Core)
OSType:?linux
Architecture:?x86_64
Number?of?Docker?Hooks:?3
CPUs:?1
Total?Memory:?2.238?GiB
Name:?manager
ID:?653Y:7CME:GFPW:35SX:IGZL:UJP7:YSPZ:4OMV:J4EV:Z6FS:WFW2:YYHS
Docker?Root?Dir:?/var/lib/docker
Debug?Mode?(client):?false
Debug?Mode?(server):?false
Registry:?https://index.docker.io/v1/
WARNING:?bridge-nf-call-ip6tables?is?disabled
Experimental:?false
Insecure?Registries:
?127.0.0.0/8
Live?Restore?Enabled:?false
Registries:?docker.io?(secure)

[root@manager?~]#?docker?node?ls
ID???????????????????????????HOSTNAME??STATUS??AVAILABILITY??MANAGER?STATUS
elyfa6h1lx5o2s98une5vas4x?*??manager???Ready???Active????????Leader
#当前节点的信息，这个*表示当前连接在这个节点上

6、将node1,node2加入到集群中

[root@node1?~]#??docker?swarm?join?--token?SWMTKN-1-32h92m334z80z270d4duqdc3ysl1oyrjmxe1upyyfjyln12xxa-4gm603mczorxgh6751n5q7jya?192.168.22.177:2377
This?node?joined?a?swarm?as?a?worker.
[root@node2?~]#?docker?swarm?join?--token?SWMTKN-1-32h92m334z80z270d4duqdc3ysl1oyrjmxe1upyyfjyln12xxa-4gm603mczorxgh6751n5q7jya?192.168.22.177:2377
This?node?joined?a?swarm?as?a?worker.
#如果加入集群时报错如下
[root@node1?~]#??docker?swarm?join?--token?SWMTKN-1-32h92m334z80z270d4duqdc3ysl1oyrjmxe1upyyfjyln12xxa-4gm603mczorxgh6751n5q7jya??192.168.22.177:2377
Error?response?from?daemon:?rpc?error:?code?=?13?desc?=?connection?error:?desc?=?"transport:?x509:?certificate?has?expired?or?is?not?yet?valid"
#注意服务器时间同步问题，解决即可。

7、管理节点查看集群节点状态

[root@manager?~]#?docker?node?ls
ID???????????????????????????HOSTNAME??STATUS??AVAILABILITY??MANAGER?STATUS
elyfa6h1lx5o2s98une5vas4x?*??manager???Ready???Active????????Leader
tcuv2p8wd6rvmwg39pdav5ozk????node1?????Ready???Active????????
twytwc5dlp77vu1b7cakks9w2????node2?????Ready???Active??
#swarm集群中node的AVAILABILITY状态有两种：Active、drain。其中actice状态的节点可以接受管理节点的任务指派；drain状态的节点会结束任务，也不会接受管理节点的任务指派，节点处于下线状态。

[root@manager?~]#?docker?node?update?--availability?drain?node2
node2
[root@manager?~]#?docker?node?ls
ID???????????????????????????HOSTNAME??STATUS??AVAILABILITY??MANAGER?STATUS
elyfa6h1lx5o2s98une5vas4x?*??manager???Ready???Active????????Leader
tcuv2p8wd6rvmwg39pdav5ozk????node1?????Ready???Active????????
twytwc5dlp77vu1b7cakks9w2????node2?????Ready???Drain??
[root@manager?~]#?docker?node?update?--availability?active?node2
node2
[root@manager?~]#?docker?node?ls
ID???????????????????????????HOSTNAME??STATUS??AVAILABILITY??MANAGER?STATUS
elyfa6h1lx5o2s98une5vas4x?*??manager???Ready???Active????????Leader
tcuv2p8wd6rvmwg39pdav5ozk????node1?????Ready???Active????????
twytwc5dlp77vu1b7cakks9w2????node2?????Ready???Active?

#在manager节点上查看状态信息
[root@manager?~]#?docker?node?inspect?self
[
????{
????????"ID":?"elyfa6h1lx5o2s98une5vas4x",
????????"Version":?{
????????????"Index":?9
????????},
????????"CreatedAt":?"2018-06-14T15:01:19.850821157Z",
????????"UpdatedAt":?"2018-06-14T15:01:20.472379584Z",
????????"Spec":?{
????????????"Role":?"manager",
????????????"Availability":?"active"
????????},
????????"Description":?{
????????????"Hostname":?"manager",
????????????"Platform":?{
????????????????"Architecture":?"x86_64",
????????????????"OS":?"linux"
????????????},
????????????"Resources":?{
????????????????"NanoCPUs":?1000000000,
????????????????"MemoryBytes":?2402566144
????????????},
????????????"Engine":?{
????????????????"EngineVersion":?"1.13.1",
????????????????"Plugins":?[
????????????????????{
????????????????????????"Type":?"Network",
????????????????????????"Name":?"bridge"
????????????????????},
????????????????????{
????????????????????????"Type":?"Network",
????????????????????????"Name":?"host"
????????????????????},
????????????????????{
????????????????????????"Type":?"Network",
????????????????????????"Name":?"macvlan"
????????????????????},
????????????????????{
????????????????????????"Type":?"Network",
????????????????????????"Name":?"null"
????????????????????},
????????????????????{
????????????????????????"Type":?"Network",
????????????????????????"Name":?"overlay"
????????????????????},
????????????????????{
????????????????????????"Type":?"Volume",
????????????????????????"Name":?"local"
????????????????????}
????????????????]
????????????}
????????},
????????"Status":?{
????????????"State":?"ready",
????????????"Addr":?"127.0.0.1"
????????},
????????"ManagerStatus":?{
????????????"Leader":?true,
????????????"Reachability":?"reachable",
????????????"Addr":?"192.168.22.177:2377"
????????}
????}
]

Swarm 的Web管理

[root@manager?~]#?docker?run?-d?-p?9000:9000?-v?/var/run/docker.sock:/var/run/docker.sock?portainer/portainer
Unable?to?find?image?'portainer/portainer:latest'?locally
Trying?to?pull?repository?docker.io/portainer/portainer?...?
latest:?Pulling?from?docker.io/portainer/portainer
d1e017099d17:?Pull?complete?
0d90a7ef0797:?Pull?complete?
Digest:?sha256:2933caa6e578e94b5d91429ea7f47ae9741ee11b71d7cb740e76c5f234cc1d87
Status:?Downloaded?newer?image?for?docker.io/portainer/portainer:latest
798b3bea009792321519f5b7144e357ce9c5cea3b9341b5276a4d29f7571684a
[root@manager?~]#?docker?ps
CONTAINER?ID??IMAGE?????????????????COMMAND????????CREATED????????STATUS????????PORTS????????????????????NAMES
798b3bea0097??portainer/portainer???"/portainer"???6?seconds?ago??Up?5?seconds??0.0.0.0:9000->9000/tcp???amazing_snyder

浏览器访问

docker-swarm布署服务

1、布署服务前创建于个用于集群内不同主机之间容器通信的网络

[root@manager?~]#?docker?network?create?-d?overlay?dockernet
pmn1fi6lj421hn1nk7652m41h
[root@manager?~]#?docker?network?ls
NETWORK?ID??????????NAME????????????????DRIVER??????????????SCOPE
d913c7a275fe????????bridge??????????????bridge??????????????local
c737cf269524????????docker_gwbridge?????bridge??????????????local
pmn1fi6lj421????????dockernet???????????overlay?????????????swarm
eac1d68d35d7????????host????????????????host????????????????local
wxshzhdvq52y????????ingress?????????????overlay?????????????swarm
c5986aec6119????????none????????????????null????????????????local

2、创建服务(nginx为例)

[root@manager?~]#?docker?service?create?--replicas?1?--network?dockernet?--name?nginx-cluster?-p?80:80?nginx
k7lupo9xu0cnd5ng1g4f7i7jx
#--replicas?指定副本数量
[root@manager?~]#?docker?service?ls
ID????????????NAME???????????MODE????????REPLICAS??IMAGE
k7lupo9xu0cn??nginx-cluster??replicated??1/1???????nginx:latest
[root@manager?~]#?docker?service?ps?nginx-cluster
ID????????????NAME?????????????IMAGE?????????NODE?????DESIRED?STATE??CURRENT?STATE???????????ERROR??PORTS
7t7xjpmao533??nginx-cluster.1??nginx:latest??manager??Running????????Running?17?seconds?ago?????????
[root@manager?~]#?docker?ps
CONTAINER?ID???IMAGE???????????????????????????????????????????????????????????????????????????COMMAND??????????????????CREATED?????????????STATUS??????????????PORTS?????NAMES
a9d78079fdc7??nginx@sha256:3e2ffcf0edca2a4e9b24ca442d227baea7b7f0e33ad654ef1eb806fbd9bedcf0???"nginx?-g?'daemon?..."???22?seconds?ago??????Up?22?seconds???????80/tcp?????nginx-cluster.1.7t7xjpmao5335zaa8wp0c896a

3、在线动态扩容服务

[root@manager?~]#?docker?service?scale?nginx-cluster=5
nginx-cluster?scaled?to?5
[root@manager?~]#?docker?service?ps?nginx-cluster
ID????????????NAME?????????????IMAGE?????????NODE?????DESIRED?STATE??CURRENT?STATE????????????ERROR??PORTS
7t7xjpmao533??nginx-cluster.1??nginx:latest??manager??Running????????Running?2?hours?ago?????????????
vitsgxpdf3bn??nginx-cluster.2??nginx:latest??manager??Running????????Running?2?seconds?ago???????????
o9w529mmttsw??nginx-cluster.3??nginx:latest??node1????Running????????Preparing?2?seconds?ago?????????
cfz8dkx9p6ih??nginx-cluster.4??nginx:latest??node2????Running????????Preparing?2?seconds?ago?????????
9p35iunijoro??nginx-cluster.5??nginx:latest??node2????Running????????Preparing?2?seconds?ago????
#从输出结果可以看出已经将服务动态扩容至5个，也就是5个容器运行着相同的服务
[root@node2?~]#?docker?ps
CONTAINER?ID???IMAGE???????????????????????????????????????????????????????????????????????????COMMAND??????????????????CREATED?????????STATUS????????PORTS???NAMES
f3a4fb24480a???nginx@sha256:3e2ffcf0edca2a4e9b24ca442d227baea7b7f0e33ad654ef1eb806fbd9bedcf0???"nginx?-g?'daemon?..."???3?minutes?ago???Up?3?minutes??80/tcp??nginx-cluster.5.9p35iunijorol1d2ikhyj11oi
f8b0b2e514eb???nginx@sha256:3e2ffcf0edca2a4e9b24ca442d227baea7b7f0e33ad654ef1eb806fbd9bedcf0???"nginx?-g?'daemon?..."???3?minutes?ago???Up?3?minutes??80/tcp??nginx-cluster.4.cfz8dkx9p6ih40lwwwvd96xdg
#登录node2查看正在运行的容器，发现与管理节点上显示的结果相同，node2上运行两个容器

4、节点故障

[root@manager?~]#?docker?service?ps?nginx-cluster
ID????????????NAME?????????????????IMAGE?????????NODE?????DESIRED?STATE??CURRENT?STATE???????????ERROR?????????????????????????????PORTS
7t7xjpmao533??nginx-cluster.1??????nginx:latest??manager??Running????????Running?2?hours?ago???????????????????????????????????????
vitsgxpdf3bn??nginx-cluster.2??????nginx:latest??manager??Running????????Running?10?minutes?ago????????????????????????????????????
f13cun1wyxlt??nginx-cluster.3??????nginx:latest??manager??Running????????Running?9?minutes?ago?????????????????????????????????????
q60fo5mja1ab???\_?nginx-cluster.3??nginx:latest??node1????Shutdown???????Failed?9?minutes?ago????"starting?container?failed:?sh…"??
mao4htxp7afr???\_?nginx-cluster.3??nginx:latest??node1????Shutdown???????Failed?9?minutes?ago????"starting?container?failed:?sh…"??
fhiecco742y4???\_?nginx-cluster.3??nginx:latest??node1????Shutdown???????Failed?10?minutes?ago???"starting?container?failed:?sh…"??
8qp5kryo62ha???\_?nginx-cluster.3??nginx:latest??node1????Shutdown???????Failed?10?minutes?ago???"starting?container?failed:?sh…"??
cfz8dkx9p6ih??nginx-cluster.4??????nginx:latest??node2????Running????????Running?9?minutes?ago?????????????????????????????????????
9p35iunijoro??nginx-cluster.5??????nginx:latest??node2????Running????????Running?9?minutes?ago??
#如果集群中节点发生故障，会从swarm集群中被T除，然后利用自身的负载均衡及调度功能，将服务调度到其它节点上

5、其它常用命令介绍

除了上面使用scale来实现在线动态扩容、缩容之外，还可以使用update来对服务进行调整

[root@manager?~]#?docker?service?ls
ID????????????NAME???????????MODE????????REPLICAS??IMAGE
k7lupo9xu0cn??nginx-cluster??replicated??5/5???????nginx:latest
[root@manager?~]#?docker?service?update?--replicas?2?nginx-cluster
nginx-cluster
[root@manager?~]#?docker?service?ls
ID????????????NAME???????????MODE????????REPLICAS??IMAGE
k7lupo9xu0cn??nginx-cluster??replicated??2/2???????nginx:latest
#将服务缩减到2个

[root@manager?~]#?docker?service?update?--image?nginx:new?nginx-cluster
#更新服务的镜像版本

[root@manager?~]#?docker?service?--help?

Usage:????docker?service?COMMAND

Manage?services

Options:
??????--help???Print?usage

Commands:
??create??????Create?a?new?service
??inspect?????Display?detailed?information?on?one?or?more?services
??ls??????????List?services
??ps??????????List?the?tasks?of?a?service
??rm??????????Remove?one?or?more?services
??scale???????Scale?one?or?multiple?replicated?services
??update??????Update?a?service

Run?'docker?service?COMMAND?--help'?for?more?information?on?a?command.
[root@manager?~]#?docker?rm?nginx-cluster
#将所有节点上的所有容器全部删除，任务也将全部删除

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送你 8 张图，好好理解一下。

·end·

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