Docker ------ Swarm 初探
Docker-Swarm 初探
作者：elfin 资料来源：遇见狂神说
1、环境准备
Docker Swarm是docker三剑客之一，Swarm 是 Docker 原生的集群搭建项目，同时也是最简单，最易学，最节省资源的，比较适合中小型公司使用。更多性能介绍可以参考纯洁的微笑。简易学习教程可以参考菜鸟教程。
Swarm本身很简单，但是在学习集群的过程中，你怎么能可以几台机子用于测试呢，伪分布式？额，算了吧，阿里云4台机子0.8元/h，难道不香吗？
1.1 购买实例
这里我们在阿里云上购买4台机子用于说明，选择按量付费模式，用后及时销毁，毕竟家境贫寒！下面介绍操作步骤，阿里云界面可能会调整，但是大差不差，步骤总是问题不大。
服务器购买页面：
A(百度：阿里云，进入官网) --> B(登录并进入控制台) --> C(左侧侧边栏：云服务器ECS) --> D(我的资源：创建实例或创建我的ECS)；
购买需要的服务器：
A(创建我的ECS) --> B(按量付费、选择离你近的区域、分类：共享型1核2G、4台、选择镜像：centos7) --> C(进入下一步，调整带宽，其他默认即可，下一步) --> D(自定义密码、自定义实例名，下一步) --> E(下一步确认订单：确认好基本信息即可购买)
1.2 连接服务器
1.2.1 连接4台服务器
使用xshell连接你刚刚购买的服务器，恰好，xshell免费版的支持四个窗口，对于家境贫寒的我们简直不要太耐撕。
在终端内右键选择将命令输入到其他窗口！这里是为了统一安装环境，总不能咱一个个安装吧！
检查每个服务器都安装好了，下面进入docker安装环节…
1.2.2 安装docker
docker的安装可参考官方教程。
安装步骤：
-
确保环境是centos7及以上版本，这里买服务器时就选择了！
-
yum安装gcc相关环境，需要确保虚拟机可以上外网
$ yum -y install gcc $ yum -y install gcc-c++ -
卸载旧版本
$ sudo yum remove docker \ docker-client \ docker-client-latest \ docker-common \ docker-latest \ docker-latest-logrotate \ docker-logrotate \ docker-engine -
安装依赖、设置镜像仓库
$ sudo yum install -y yum-utils $ sudo yum-config-manager \ --add-repo \ https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo -
更新yum软件包索引
$ yum makecache fast -
安装Docker-ce
$ sudo yum install docker-ce docker-ce-cli containerd.io -
启动Docker
$ systemctl start docker -
测试命令
$ docker version $ docker run hello-world $ docker images -
配置镜像加速
$ sudo mkdir -p /etc/docker $ sudo tee /etc/docker/daemon.json <<-'EOF' { "registry-mirrors": ["https://qiyb9988.mirror.aliyuncs.com"] } EOF $ sudo systemctl daemon-reload $ sudo systemctl restart docker这里注意json文件格式的正确，直接复制会出错！
2、工作模式
官方的工作模式介绍
Docker Engine 1.12引入了swarm模式，使您能够创建一个由一个或多个Docker引擎组成的集群，称为swarm。swarm由一个或多个节点组成：在swarm模式下运行Docker Engine 1.12或更高版本的物理或虚拟机。
有两种类型的节点：managers和workers。
worker是不能操作managers的！主节点不能只有一个，也不能使用两个！至少使用3个。
3、集群搭建
3.1 查看当前的docker环境
[root@iZ2vcf0atudng87wzoeelcZ ~]# docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
[root@iZ2vcf0atudng87wzoeelcZ ~]# docker network ls
NETWORK ID NAME DRIVER SCOPE
f555f5076970 bridge bridge local
cf030c9a10db host host local
f6484ff6e7c6 none null local
3.2 查看docker swarm的命令
[root@iZ2vcf0atudng87wzoeelcZ ~]# docker swarm --help
Usage: docker swarm COMMAND
Manage Swarm
Commands:
ca Display and rotate the root CA
init Initialize a swarm
join Join a swarm as a node and/or manager
join-token Manage join tokens
leave Leave the swarm
unlock Unlock swarm
unlock-key Manage the unlock key
update Update the swarm
Run 'docker swarm COMMAND --help' for more information on a command.
3.3 查看docker swarm init的命令
[root@iZ2vcf0atudng87wzoeelcZ ~]# docker swarm init --help
Usage: docker swarm init [OPTIONS]
Initialize a swarm
Options:
--advertise-addr string Advertised address (format: <ip|interface>[:port])
--autolock Enable manager autolocking (requiring an unlock key to start a stopped manager)
--availability string Availability of the node ("active"|"pause"|"drain") (default "active")
--cert-expiry duration Validity period for node certificates (ns|us|ms|s|m|h) (default 2160h0m0s)
--data-path-addr string Address or interface to use for data path traffic (format: <ip|interface>)
--data-path-port uint32 Port number to use for data path traffic (1024 - 49151). If no value is set
or is set to 0, the default port (4789) is used.
--default-addr-pool ipNetSlice default address pool in CIDR format (default [])
--default-addr-pool-mask-length uint32 default address pool subnet mask length (default 24)
--dispatcher-heartbeat duration Dispatcher heartbeat period (ns|us|ms|s|m|h) (default 5s)
--external-ca external-ca Specifications of one or more certificate signing endpoints
--force-new-cluster Force create a new cluster from current state
--listen-addr node-addr Listen address (format: <ip|interface>[:port]) (default 0.0.0.0:2377)
--max-snapshots uint Number of additional Raft snapshots to retain
--snapshot-interval uint Number of log entries between Raft snapshots (default 10000)
--task-history-limit int Task history retention limit (default 5)
--advertise-addr 必须要配置！
查看服务器elfin04的地址(内网)：
[root@iZ2vcf0atudng87wzoeelcZ ~]# 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
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
link/ether 00:16:3e:01:51:0d brd ff:ff:ff:ff:ff:ff
inet 172.28.58.219/20 brd 172.28.63.255 scope global dynamic eth0
valid_lft 315358385sec preferred_lft 315358385sec
inet6 fe80::216:3eff:fe01:510d/64 scope link
valid_lft forever preferred_lft forever
3: docker0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default
link/ether 02:42:de:7a:76:d8 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
当前服务器的地址为172.28.58.219
3.4 创建主节点
[root@iZ2vcf0atudng87wzoeelcZ ~]# docker swarm init --advertise-addr 172.28.58.219
Swarm initialized: current node (xron1grqswlita8xrcwr2d3y5) is now a manager.
To add a worker to this swarm, run the following command:
docker swarm join --token SWMTKN-1-4gb44r3ekdejhtdp0fzc1o3dqdplrobqnjgaojtaghgpdaqjkx-9jl64hbbhul3th0b6jjf6ikji 172.28.58.219:2377
To add a manager to this swarm, run 'docker swarm join-token manager' and follow the instructions.
上面的信息表明，当前节点是一个manager节点，添加工作节点的命令为：docker swarm join --token SWMTKN-1-4gb44r3ekdejhtdp0fzc1o3dqdplrobqnjgaojtaghgpdaqjkx-9jl64hbbhul3th0b6jjf6ikji 172.28.58.219:2377，注意这里的token相当于认证！最后一行说明了如何添加管理节点。
3.5 从节点加入主节点
在3.4中创建主节点时生成了两个令牌：
# 将其他服务器直接加入当前的主节点
docker swarm join --token SWMTKN-1-4gb44r3ekdejhtdp0fzc1o3dqdplrobqnjgaojtaghgpdaqjkx-9jl64hbbhul3th0b6jjf6ikji 172.28.58.219:2377
# 生成其他主节点的令牌命令(在当前主节点生成后复制到其他服务器使用)
docker swarm join-token manager
# 生成其他从节点的命令
docker swarm join-token worker
现在让elfin03加入elfin04这个主节点
[root@iZ2vcf0atudng87wzoeelbZ ~]# docker swarm join --token SWMTKN-1-4gb44r3ekdejhtdp0fzc1o3dqdplrobqnjgaojtaghgpdaqjkx-9jl64hbbhul3th0b6jjf6ikji 172.28.58.219:2377
This node joined a swarm as a worker.
现在elfin03通过上面的命令加入了主节点！
查看当前的节点信息：
# elfin04主节点中执行
[root@iZ2vcf0atudng87wzoeelcZ ~]# docker node ls
ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS ENGINE VERSION
llqvxni8acep3zx2s93s6kexx iZ2vcf0atudng87wzoeelbZ Ready Active 20.10.0
xron1grqswlita8xrcwr2d3y5 * iZ2vcf0atudng87wzoeelcZ Ready Active Leader 20.10.0
可以发现有两个节点，Leader即为我们的elfin04主节点(观察HOSTNAME)！
生成其他worker加入的令牌：
docker swarm join --token SWMTKN-1-4gb44r3ekdejhtdp0fzc1o3dqdplrobqnjgaojtaghgpdaqjkx-9jl64hbbhul3th0b6jjf6ikji 172.28.58.219:2377
当前的令牌和init时生成的是一样的！
让elfin02加入elfin04主节点
# 在elfin02中执行
[root@iZ2vcf0atudng87wzoeelaZ ~]# docker swarm join --token SWMTKN-1-4gb44r3ekdejhtdp0fzc1o3dqdplrobqnjgaojtaghgpdaqjkx-9jl64hbbhul3th0b6jjf6ikji 172.28.58.219:2377
This node joined a swarm as a worker.
# 在elfin04中执行
[root@iZ2vcf0atudng87wzoeelcZ ~]# docker node ls
ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS ENGINE VERSION
flxmp7ppfmd6vadxn8q6hx0ch iZ2vcf0atudng87wzoeelaZ Ready Active 20.10.0
llqvxni8acep3zx2s93s6kexx iZ2vcf0atudng87wzoeelbZ Ready Active 20.10.0
xron1grqswlita8xrcwr2d3y5 * iZ2vcf0atudng87wzoeelcZ Ready Active Leader 20.10.0
iZ2vcf0atudng87wzoeelaZ表明elfin02加入了集群！
3.6 创建其他manager节点
# 在elfin04中执行
[root@iZ2vcf0atudng87wzoeelcZ ~]# docker swarm join-token manager
To add a manager to this swarm, run the following command:
docker swarm join --token SWMTKN-1-4gb44r3ekdejhtdp0fzc1o3dqdplrobqnjgaojtaghgpdaqjkx-32usnk3wlcpe9jn3nylwngd35 172.28.58.219:2377
将elfin01加入elfin04所在集群，且作为一个主节点：
# 在elfin01中执行
[root@iZ2vcf0atudng87wzoeel9Z ~]# docker swarm join --token SWMTKN-1-4gb44r3ekdejhtdp0fzc1o3dqdplrobqnjgaojtaghgpdaqjkx-32usnk3wlcpe9jn3nylwngd35 172.28.58.219:2377
This node joined a swarm as a manager.
[root@iZ2vcf0atudng87wzoeel9Z ~]# docker node ls
ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS ENGINE VERSION
s7negfbauav9sgwsgggr1vj75 * iZ2vcf0atudng87wzoeel9Z Ready Active Reachable 20.10.0
flxmp7ppfmd6vadxn8q6hx0ch iZ2vcf0atudng87wzoeelaZ Ready Active 20.10.0
llqvxni8acep3zx2s93s6kexx iZ2vcf0atudng87wzoeelbZ Ready Active 20.10.0
xron1grqswlita8xrcwr2d3y5 iZ2vcf0atudng87wzoeelcZ Ready Active Leader 20.10.0
注意，docker node ls要在主节点中执行，而 elfin01 也是主节点，但是我们观察到TD后面有星号，manager status也是Reachable！星号标识了当前处于哪个主节点，Leader你可以理解为管理节点中的大哥，如果大哥挂了，其他主节点会顺位成为大哥，嗯，整的像黑社会似的。
3.7 集群的leave
实验
停止elfin04中的docker，在elfin01中测试docker node ls
# elfin04
[root@iZ2vcf0atudng87wzoeelcZ ~]# systemctl stop docker
Warning: Stopping docker.service, but it can still be activated by:
docker.socket
# elfin01
[root@iZ2vcf0atudng87wzoeel9Z ~]# docker node ls
Error response from daemon: rpc error: code = Unknown desc = The swarm does not have a leader. It's possible that too few managers are online. Make sure more than half of the managers are online.
上面的结果说明现在集群没有Leader了，这是为什么呢，elfin01不是应该上位吗？这里要注意要满足Raft协议。
恢复elfin04查看变化
# elfin04
[root@iZ2vcf0atudng87wzoeelcZ ~]# systemctl start docker
[root@iZ2vcf0atudng87wzoeelcZ ~]# docker node ls
ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS ENGINE VERSION
s7negfbauav9sgwsgggr1vj75 iZ2vcf0atudng87wzoeel9Z Ready Active Leader 20.10.0
flxmp7ppfmd6vadxn8q6hx0ch iZ2vcf0atudng87wzoeelaZ Ready Active 20.10.0
llqvxni8acep3zx2s93s6kexx iZ2vcf0atudng87wzoeelbZ Ready Active 20.10.0
xron1grqswlita8xrcwr2d3y5 * iZ2vcf0atudng87wzoeelcZ Ready Active Reachable 20.10.0
现在您可以发现elfin04进去集群了，但是它已经不当大哥好多年！变成Reachable的管理节点了。
现在让elfin03离开集群
[root@iZ2vcf0atudng87wzoeelbZ ~]# docker swarm leave
Node left the swarm.
# elfin04
[root@iZ2vcf0atudng87wzoeelcZ ~]# docker node ls
ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS ENGINE VERSION
s7negfbauav9sgwsgggr1vj75 iZ2vcf0atudng87wzoeel9Z Ready Active Leader 20.10.0
flxmp7ppfmd6vadxn8q6hx0ch iZ2vcf0atudng87wzoeelaZ Ready Active 20.10.0
llqvxni8acep3zx2s93s6kexx iZ2vcf0atudng87wzoeelbZ Down Active 20.10.0
xron1grqswlita8xrcwr2d3y5 * iZ2vcf0atudng87wzoeelcZ Ready Active Reachable 20.10.0
可以看见status变为Down了！
3.8 生成三个manager
# elfin04
[root@iZ2vcf0atudng87wzoeelcZ ~]# docker swarm join-token manager
To add a manager to this swarm, run the following command:
docker swarm join --token SWMTKN-1-4gb44r3ekdejhtdp0fzc1o3dqdplrobqnjgaojtaghgpdaqjkx-32usnk3wlcpe9jn3nylwngd35 172.28.58.219:2377
# elfin03
[root@iZ2vcf0atudng87wzoeelbZ ~]# docker swarm join --token SWMTKN-1-4gb44r3ekdejhtdp0fzc1o3dqdplrobqnjgaojtaghgpdaqjkx-32usnk3wlcpe9jn3nylwngd35 172.28.58.219:2377
This node joined a swarm as a manager.
[root@iZ2vcf0atudng87wzoeelbZ ~]# docker node ls
ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS ENGINE VERSION
s7negfbauav9sgwsgggr1vj75 iZ2vcf0atudng87wzoeel9Z Ready Active Leader 20.10.0
flxmp7ppfmd6vadxn8q6hx0ch iZ2vcf0atudng87wzoeelaZ Ready Active 20.10.0
llqvxni8acep3zx2s93s6kexx iZ2vcf0atudng87wzoeelbZ Down Active 20.10.0
u44zzj5jetxxetkblnx75qr82 * iZ2vcf0atudng87wzoeelbZ Ready Active Reachable 20.10.0
xron1grqswlita8xrcwr2d3y5 iZ2vcf0atudng87wzoeelcZ Ready Active Reachable 20.10.0
# 当前有三个主节点了！显示elfin03 Down了我们不用管……
注意：此时我停止Leader，在其他主节点使用docker node ls，效果如下：
[root@iZ2vcf0atudng87wzoeelbZ ~]# docker node ls
ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS ENGINE VERSION
s7negfbauav9sgwsgggr1vj75 iZ2vcf0atudng87wzoeel9Z Down Active Unreachable 20.10.0
flxmp7ppfmd6vadxn8q6hx0ch iZ2vcf0atudng87wzoeelaZ Ready Active 20.10.0
llqvxni8acep3zx2s93s6kexx iZ2vcf0atudng87wzoeelbZ Down Active 20.10.0
u44zzj5jetxxetkblnx75qr82 * iZ2vcf0atudng87wzoeelbZ Ready Active Leader 20.10.0
xron1grqswlita8xrcwr2d3y5 iZ2vcf0atudng87wzoeelcZ Ready Active Reachable 20.10.0
明显elfin01显示Unreachable了，而此时小弟elfin03上位成功了，终于熬成Leader了！
此时是符合Raft协议的，即我们要满足大多数原则，只有两个主节点，坏一个就只有一个，就不能满足大多数！所以集群至少要有两个主节点。
3.9 小节
- 生成主节点
- 加入（管理者manager、worker）
- work就是工作的，manager就是管理的！
将主节点全部启动起来。使集群正常……
4、集群应用部署
这一节我们主要是体验弹性、扩缩容。以后就不要使用docker run进行启动部署了，当然docker-compose up也不适合你，一般部署项目我们最好是集群，这样可以高可用、高可靠。
一般的小公司，使用swarm就足够了，如果非要使用K8S也是可以的……
为什么要使用集群？因为我们想要应用高可用，访问的时候我们也不需要指定某个机器，如访问redis数据库，我们只需使用redis就好；当访问量过大需要扩容时，你确定不用集群吗？
这里我们主要体验：创建服务、动态扩展服务、动态更新服务。
4.1 创建服务
4.1.1 查看服务docker service的基本命令
[root@iZ2vcf0atudng87wzoeel9Z ~]# docker service --help
Usage: docker service COMMAND
Manage services
Commands:
create Create a new service
inspect Display detailed information on one or more services
logs Fetch the logs of a service or task
ls List services
ps List the tasks of one or more services
rm Remove one or more services
rollback Revert changes to a service's configuration
scale Scale one or multiple replicated services
update Update a service
Run 'docker service COMMAND --help' for more information on a command.
4.1.2 查看创建服务的命令
[root@iZ2vcf0atudng87wzoeel9Z ~]# docker service create --help
Usage: docker service create [OPTIONS] IMAGE [COMMAND] [ARG...]
Create a new service
Options:
--cap-add list Add Linux capabilities
--cap-drop list Drop Linux capabilities
--config config Specify configurations to expose to the service
--constraint list Placement constraints
--container-label list Container labels
--credential-spec credential-spec Credential spec for managed service account (Windows only)
-d, --detach Exit immediately instead of waiting for the service to converge
--dns list Set custom DNS servers
--dns-option list Set DNS options
--dns-search list Set custom DNS search domains
--endpoint-mode string Endpoint mode (vip or dnsrr) (default "vip")
--entrypoint command Overwrite the default ENTRYPOINT of the image
-e, --env list Set environment variables
--env-file list Read in a file of environment variables
--generic-resource list User defined resources
--group list Set one or more supplementary user groups for the container
--health-cmd string Command to run to check health
--health-interval duration Time between running the check (ms|s|m|h)
--health-retries int Consecutive failures needed to report unhealthy
--health-start-period duration Start period for the container to initialize before counting retries towards
unstable (ms|s|m|h)
--health-timeout duration Maximum time to allow one check to run (ms|s|m|h)
--host list Set one or more custom host-to-IP mappings (host:ip)
--hostname string Container hostname
--init Use an init inside each service container to forward signals and reap processes
--isolation string Service container isolation mode
-l, --label list Service labels
--limit-cpu decimal Limit CPUs
--limit-memory bytes Limit Memory
--limit-pids int Limit maximum number of processes (default 0 = unlimited)
--log-driver string Logging driver for service
--log-opt list Logging driver options
--max-concurrent uint Number of job tasks to run concurrently (default equal to --replicas)
--mode string Service mode (replicated, global, replicated-job, or global-job) (default
"replicated")
--mount mount Attach a filesystem mount to the service
--name string Service name
--network network Network attachments
--no-healthcheck Disable any container-specified HEALTHCHECK
--no-resolve-image Do not query the registry to resolve image digest and supported platforms
--placement-pref pref Add a placement preference
-p, --publish port Publish a port as a node port
-q, --quiet Suppress progress output
--read-only Mount the container's root filesystem as read only
--replicas uint Number of tasks
--replicas-max-per-node uint Maximum number of tasks per node (default 0 = unlimited)
--reserve-cpu decimal Reserve CPUs
--reserve-memory bytes Reserve Memory
--restart-condition string Restart when condition is met ("none"|"on-failure"|"any") (default "any")
--restart-delay duration Delay between restart attempts (ns|us|ms|s|m|h) (default 5s)
--restart-max-attempts uint Maximum number of restarts before giving up
--restart-window duration Window used to evaluate the restart policy (ns|us|ms|s|m|h)
--rollback-delay duration Delay between task rollbacks (ns|us|ms|s|m|h) (default 0s)
--rollback-failure-action string Action on rollback failure ("pause"|"continue") (default "pause")
--rollback-max-failure-ratio float Failure rate to tolerate during a rollback (default 0)
--rollback-monitor duration Duration after each task rollback to monitor for failure (ns|us|ms|s|m|h)
(default 5s)
--rollback-order string Rollback order ("start-first"|"stop-first") (default "stop-first")
--rollback-parallelism uint Maximum number of tasks rolled back simultaneously (0 to roll back all at once)
(default 1)
--secret secret Specify secrets to expose to the service
--stop-grace-period duration Time to wait before force killing a container (ns|us|ms|s|m|h) (default 10s)
--stop-signal string Signal to stop the container
--sysctl list Sysctl options
-t, --tty Allocate a pseudo-TTY
--ulimit ulimit Ulimit options (default [])
--update-delay duration Delay between updates (ns|us|ms|s|m|h) (default 0s)
--update-failure-action string Action on update failure ("pause"|"continue"|"rollback") (default "pause")
--update-max-failure-ratio float Failure rate to tolerate during an update (default 0)
--update-monitor duration Duration after each task update to monitor for failure (ns|us|ms|s|m|h) (default 5s)
--update-order string Update order ("start-first"|"stop-first") (default "stop-first")
--update-parallelism uint Maximum number of tasks updated simultaneously (0 to update all at once) (default 1)
-u, --user string Username or UID (format: <name|uid>[:<group|gid>])
--with-registry-auth Send registry authentication details to swarm agents
-w, --workdir string Working directory inside the container
4.1.3 创建一个服务
# elfin01
[root@iZ2vcf0atudng87wzoeel9Z ~]# docker service create -p 8888:80 --name my_nginx nginx
3zs3vzn8aqh6mjhoawbcysl96
overall progress: 1 out of 1 tasks
1/1: running [==================================================>]
verify: Service converged
注意：
- docker run 容器启动！不具有扩缩容
- dockerservice 服务化启动！具有扩缩容、滚动更新！
4.2 查看我们的服务
# elfin01
[root@iZ2vcf0atudng87wzoeel9Z ~]# docker service ps my_nginx
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
byfl43zh4ltb my_nginx.1 nginx:latest iZ2vcf0atudng87wzoeelaZ Running Running 3 minutes ago
# elfin03
[root@iZ2vcf0atudng87wzoeelbZ ~]# docker service ps my_nginx
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
byfl43zh4ltb my_nginx.1 nginx:latest iZ2vcf0atudng87wzoeelaZ Running Running 4 minutes ago
[root@iZ2vcf0atudng87wzoeelbZ ~]# docker service ls
ID NAME MODE REPLICAS IMAGE PORTS
3zs3vzn8aqh6 my_nginx replicated 1/1 nginx:latest *:8888->80/tcp
这里只启动了一个nginx，只有一个副本，这好像部署我们想要的结果……
如果你想看具体的信息，可以使用docker service inspect my_nginx，这里的命令和docker的基本命令相似，只是加了一个service。
4.3更新服务
查看update的基本命令
[root@iZ2vcf0atudng87wzoeelbZ ~]# docker service update --help
Usage: docker service update [OPTIONS] SERVICE
Update a service
Options:
--args command Service command args
--cap-add list Add Linux capabilities
--cap-drop list Drop Linux capabilities
--config-add config Add or update a config file on a service
--config-rm list Remove a configuration file
--constraint-add list Add or update a placement constraint
--constraint-rm list Remove a constraint
--container-label-add list Add or update a container label
--container-label-rm list Remove a container label by its key
--credential-spec credential-spec Credential spec for managed service account (Windows only)
-d, --detach Exit immediately instead of waiting for the service to converge
--dns-add list Add or update a custom DNS server
--dns-option-add list Add or update a DNS option
--dns-option-rm list Remove a DNS option
--dns-rm list Remove a custom DNS server
--dns-search-add list Add or update a custom DNS search domain
--dns-search-rm list Remove a DNS search domain
--endpoint-mode string Endpoint mode (vip or dnsrr)
--entrypoint command Overwrite the default ENTRYPOINT of the image
--env-add list Add or update an environment variable
--env-rm list Remove an environment variable
--force Force update even if no changes require it
--generic-resource-add list Add a Generic resource
--generic-resource-rm list Remove a Generic resource
--group-add list Add an additional supplementary user group to the container
--group-rm list Remove a previously added supplementary user group from the container
--health-cmd string Command to run to check health
--health-interval duration Time between running the check (ms|s|m|h)
--health-retries int Consecutive failures needed to report unhealthy
--health-start-period duration Start period for the container to initialize before counting retries towards
unstable (ms|s|m|h)
--health-timeout duration Maximum time to allow one check to run (ms|s|m|h)
--host-add list Add a custom host-to-IP mapping (host:ip)
--host-rm list Remove a custom host-to-IP mapping (host:ip)
--hostname string Container hostname
--image string Service image tag
--init Use an init inside each service container to forward signals and reap processes
--isolation string Service container isolation mode
--label-add list Add or update a service label
--label-rm list Remove a label by its key
--limit-cpu decimal Limit CPUs
--limit-memory bytes Limit Memory
--limit-pids int Limit maximum number of processes (default 0 = unlimited)
--log-driver string Logging driver for service
--log-opt list Logging driver options
--max-concurrent uint Number of job tasks to run concurrently (default equal to --replicas)
--mount-add mount Add or update a mount on a service
--mount-rm list Remove a mount by its target path
--network-add network Add a network
--network-rm list Remove a network
--no-healthcheck Disable any container-specified HEALTHCHECK
--no-resolve-image Do not query the registry to resolve image digest and supported platforms
--placement-pref-add pref Add a placement preference
--placement-pref-rm pref Remove a placement preference
--publish-add port Add or update a published port
--publish-rm port Remove a published port by its target port
-q, --quiet Suppress progress output
--read-only Mount the container's root filesystem as read only
--replicas uint Number of tasks
--replicas-max-per-node uint Maximum number of tasks per node (default 0 = unlimited)
--reserve-cpu decimal Reserve CPUs
--reserve-memory bytes Reserve Memory
--restart-condition string Restart when condition is met ("none"|"on-failure"|"any")
--restart-delay duration Delay between restart attempts (ns|us|ms|s|m|h)
--restart-max-attempts uint Maximum number of restarts before giving up
--restart-window duration Window used to evaluate the restart policy (ns|us|ms|s|m|h)
--rollback Rollback to previous specification
--rollback-delay duration Delay between task rollbacks (ns|us|ms|s|m|h)
--rollback-failure-action string Action on rollback failure ("pause"|"continue")
--rollback-max-failure-ratio float Failure rate to tolerate during a rollback
--rollback-monitor duration Duration after each task rollback to monitor for failure (ns|us|ms|s|m|h)
--rollback-order string Rollback order ("start-first"|"stop-first")
--rollback-parallelism uint Maximum number of tasks rolled back simultaneously (0 to roll back all at once)
--secret-add secret Add or update a secret on a service
--secret-rm list Remove a secret
--stop-grace-period duration Time to wait before force killing a container (ns|us|ms|s|m|h)
--stop-signal string Signal to stop the container
--sysctl-add list Add or update a Sysctl option
--sysctl-rm list Remove a Sysctl option
-t, --tty Allocate a pseudo-TTY
--ulimit-add ulimit Add or update a ulimit option (default [])
--ulimit-rm list Remove a ulimit option
--update-delay duration Delay between updates (ns|us|ms|s|m|h)
--update-failure-action string Action on update failure ("pause"|"continue"|"rollback")
--update-max-failure-ratio float Failure rate to tolerate during an update
--update-monitor duration Duration after each task update to monitor for failure (ns|us|ms|s|m|h)
--update-order string Update order ("start-first"|"stop-first")
--update-parallelism uint Maximum number of tasks updated simultaneously (0 to update all at once)
-u, --user string Username or UID (format: <name|uid>[:<group|gid>])
--with-registry-auth Send registry authentication details to swarm agents
-w, --workdir string Working directory inside the container
副本设置--replicas uint
设置服务有三个副本
[root@iZ2vcf0atudng87wzoeelbZ ~]# docker service update --replicas 3 my_nginx
my_nginx
overall progress: 3 out of 3 tasks
1/3: running [==================================================>]
2/3: running [==================================================>]
3/3: running [==================================================>]
verify: Service converged
此时elfin01~elfin03都有my_nginx项目了……
访问：使用集群中的任何一个IP都可以访问到！
4.4 更新2
使用docker service scale my_nginx=5，这里动态扩缩容为副本数为5，实际上和4.1.5的update一样。
4.5 删除服务
$ docker service rm my_nginx
此时三个主节点都查不到服务！，在所有节点也找不到！
完！
清澈的爱，只为中国
