Docker Swarm 集群弹性、动态扩缩容

一、创建一个服务

1. 查看创建服务命令

[root@localhost ~]# docker service --help

Usage:  docker service COMMAND

Manage services

Commands:
  create      Create a new service        # 创建新服务
  inspect     Display detailed information on one or more services  # 检查显示一个或多个服务的详细信息
  logs        Fetch the logs of a service or task           # 日志获取服务或任务的日志
  ls          List services            # ls列表服务
  ps          List the tasks of one or more services  # ps列出一个或多个服务的任务
  rm          Remove one or more services    # rm删除一个或多个服务
  rollback    Revert changes to a service's configuration      # 回滚还原对服务配置的更改
  scale       Scale one or multiple replicated services       # 扩展一个或多个复制服务
  update      Update a service          # 更新服务

Run 'docker service COMMAND --help' for more information on a command.
[root@localhost ~]# docker service create --help

Usage:  docker service create [OPTIONS] IMAGE [COMMAND] [ARG...]
# 用法:docker 服务 创建[选项]图像[命令][参数…]
Create a new service

Options:

-p, --publish port                       Publish a port as a node port  # 将端口发布为节点端口
-u, --user string                        Username or UID (format: <name|uid>[:<group|gid>])  # 指定用户名
    --with-registry-auth                 Send registry authentication details to swarm agents
-w, --workdir string                     Working directory inside the container  #指定容器内工作目录

2. 创建一个服务

创建的swarm服务启动命令和docker run 差不多

[root@localhost ~]# docker service create -p 8081:80 --name my-nginx nginx
ubq32058ujwjrvlp8n7uqk22f
overall progress: 1 out of 1 tasks 
1/1: running   [==================================================>] 
verify: Service converged 

3. 查看启动的docker服务及列表

[root@localhost ~]# docker service ps my-nginx
ID             NAME         IMAGE          NODE                    DESIRED STATE   CURRENT STATE           ERROR     PORTS
fbtc2jpqfm0g   my-nginx.1   nginx:latest   localhost.localdomain   Running         Running 6 minutes ago   
[root@localhost ~]# docker service ls
ID             NAME       MODE         REPLICAS   IMAGE          PORTS
ubq32058ujwj   my-nginx   replicated   1/1        nginx:latest   *:8081->80/tcp

 4. 查看启动服务的详细信息

[root@localhost ~]# docker service inspect my-nginx
[
    {
        "ID": "ubq32058ujwjrvlp8n7uqk22f",
        "Version": {
            "Index": 54
        },
        "CreatedAt": "2021-03-04T02:17:57.18776573Z",
        "UpdatedAt": "2021-03-04T02:17:57.196303716Z",
        "Spec": {
            "Name": "my-nginx",
            "Labels": {},
            "TaskTemplate": {
                "ContainerSpec": {
                    "Image": "nginx:latest@sha256:f3693fe50d5b1df1ecd315d54813a77afd56b0245a404055a946574deb6b34fc",
                    "Init": false,
                    "StopGracePeriod": 10000000000,
                    "DNSConfig": {},
                    "Isolation": "default"
                },
                "Resources": {
                    "Limits": {},
                    "Reservations": {}
                },
                "RestartPolicy": {
                    "Condition": "any",
                    "Delay": 5000000000,
                    "MaxAttempts": 0
                },
                "Placement": {
                    "Platforms": [
                        {
                            "Architecture": "amd64",
                            "OS": "linux"
                        },
                        {
                            "OS": "linux"
                        },
                        {
                            "OS": "linux"
                        },
                        {
                            "Architecture": "arm64",
                            "OS": "linux"
                        },
                        {
                            "Architecture": "386",
                            "OS": "linux"
                        },
                        {
                            "Architecture": "mips64le",
                            "OS": "linux"
                        },
                        {
                            "Architecture": "ppc64le",
                            "OS": "linux"
                        },
                        {
                            "Architecture": "s390x",
                            "OS": "linux"
                        }
                    ]
                },
                "ForceUpdate": 0,
                "Runtime": "container"
            },
            "Mode": {
                "Replicated": {
                    "Replicas": 1   # 副本数量
                }
            },
            "UpdateConfig": {
                "Parallelism": 1,
                "FailureAction": "pause",
                "Monitor": 5000000000,
                "MaxFailureRatio": 0,
                "Order": "stop-first"
            },
            "RollbackConfig": {
                "Parallelism": 1,
                "FailureAction": "pause",
                "Monitor": 5000000000,
                "MaxFailureRatio": 0,
                "Order": "stop-first"
            },
            "EndpointSpec": {
                "Mode": "vip",
                "Ports": [
                    {
                        "Protocol": "tcp",
                        "TargetPort": 80,
                        "PublishedPort": 8081,
                        "PublishMode": "ingress"
                    }
                ]
            }
        },
        "Endpoint": {
            "Spec": {
                "Mode": "vip",
                "Ports": [
                    {
                        "Protocol": "tcp",
                        "TargetPort": 80,
                        "PublishedPort": 8081,
                        "PublishMode": "ingress"
                    }
                ]
            },
            "Ports": [
                {
                    "Protocol": "tcp",
                    "TargetPort": 80,
                    "PublishedPort": 8081,
                    "PublishMode": "ingress"
                }
            ],
            "VirtualIPs": [
                {
                    "NetworkID": "q24fl2e3wkw7zhdbu2a3trzpz",
                    "Addr": "10.0.0.8/24"
                }
            ]
        }
    }
]

 以上【Mode块】显示,我们的副本数现在只有一个,因为现在就启动了一个服务

5. 查看服务在Swarm集群中哪台服务器上

Manager集群节点状态查看:

[root@localhost ~]# docker node ls
ID                            HOSTNAME                STATUS    AVAILABILITY   MANAGER STATUS   ENGINE VERSION
2giiey95hal5fv2rgfmx3souu     localhost.localdomain   Down      Active                          20.10.5
65ohc7a6u28qlanpb2tygpd8k     localhost.localdomain   Ready     Active                          20.10.5
bbksnbwq0aq96ap3z6s1znk09 *   localhost.localdomain   Ready     Active         Reachable        20.10.5
ww14ifp4ki9gyw1gdhvzgbzff     localhost.localdomain   Ready     Active         Leader           20.10.5
xttcuf3iu5cvirxwwiydi3808     localhost.localdomain   Ready     Active         Reachable        20.10.5

现在docker-1、docker-3、docker-4 为Manager主节点,docker-2 为worker从节点

docker-1 查看:

[root@localhost ~]# docker ps
CONTAINER ID   IMAGE     COMMAND   CREATED   STATUS    PORTS     NAMES

 docker-2 查看:

[root@localhost ~]# docker ps
CONTAINER ID   IMAGE          COMMAND                  CREATED          STATUS          PORTS     NAMES
fcdfee3f3953   nginx:latest   "/docker-entrypoint.…"   29 minutes ago   Up 29 minutes   80/tcp    my-nginx.1.fbtc2jpqfm0gld0g7itavm0r1

 docker-3 查看:

[root@localhost ~]# docker ps 
CONTAINER ID   IMAGE     COMMAND   CREATED   STATUS    PORTS     NAMES

 docker-4 查看:

[root@localhost ~]# docker ps 
CONTAINER ID   IMAGE     COMMAND   CREATED   STATUS    PORTS     NAMES

 以上显示,服务已经被分配到了docker-2 worker从节点运行

二、弹性,动态扩缩容

 方法一:

1. 集群服务扩缩容

[root@localhost ~]# docker service update --help

Usage:  docker service update [OPTIONS] SERVICE

Update a service

Options:

-q, --quiet                              Suppress progress output
    --replicas uint                      Number of tasks          # 副本的任务数量
    --replicas-max-per-node uint         Maximum number of tasks per node (default 0 = unlimited)
[root@localhost ~]# docker service update --replicas 5 my-nginx

可以根据环境需求,进行动态扩缩服务数量,比如:10,50,100,..........  等

[root@localhost ~]# docker service ls
ID             NAME       MODE         REPLICAS   IMAGE          PORTS
ubq32058ujwj   my-nginx   replicated   5/5        nginx:latest   *:8081->80/tcp

2. 再次查看my-nginx服务详细信息

[root@localhost ~]# docker service inspect my-nginx
    {
        "ID": "ubq32058ujwjrvlp8n7uqk22f",
        "Version": {
            "Index": 61
        },
      # 此处副本数已经改成5
            "Mode": {
                "Replicated": {
                    "Replicas": 5
                }
            },

3. 4台服务器上服务分布

docker-1

 

 docker-2

 

 docker-3

 

 docker-4

方法二:

1. 查看命令使用方法

[root@localhost ~]# docker service --help

Usage:  docker service COMMAND

Manage services

Commands:
  create      Create a new service        # 创建新服务
  inspect     Display detailed information on one or more services  # 检查显示一个或多个服务的详细信息
  logs        Fetch the logs of a service or task           # 日志获取服务或任务的日志
  ls          List services            # ls列表服务
  ps          List the tasks of one or more services  # ps列出一个或多个服务的任务
  rm          Remove one or more services    # rm删除一个或多个服务
  rollback    Revert changes to a service's configuration      # 回滚还原对服务配置的更改
  scale       Scale one or multiple replicated services       # 扩展一个或多个复制服务
  update      Update a service          # 更新服务

Run 'docker service COMMAND --help' for more information on a command.
[root@localhost ~]# docker service scale --help

Usage:  docker service scale SERVICE=REPLICAS [SERVICE=REPLICAS...]

 2. 动态扩缩容服务

将服务副本数量扩容到10个

[root@localhost ~]# docker service scale my-nginx=10
my-nginx scaled to 10
overall progress: 10 out of 10 tasks 
1/10: running   
2/10: running   
3/10: running   
4/10: running   
5/10: running   
6/10: running   
7/10: running   
8/10: running   
9/10: running   
10/10: running   
verify: Service converged

3. 查看副本数量

[root@localhost ~]# docker service ls 
ID             NAME       MODE         REPLICAS   IMAGE          PORTS
ubq32058ujwj   my-nginx   replicated   10/10      nginx:latest   *:8081->80/tcp

 4. 服务器上的副本分布

docker-1

 

docker-2

 

 docker-3

 

 docker-4

5. 如果想要减少副本数量,执行:

[root@localhost ~]# docker service scale my-nginx=5
my-nginx scaled to 5
overall progress: 5 out of 5 tasks 
1/5: running   
2/5: running   
3/5: running   
4/5: running   
5/5: running   
verify: Service converged 
[root@localhost ~]# docker service ls
ID             NAME       MODE         REPLICAS   IMAGE          PORTS
ubq32058ujwj   my-nginx   replicated   5/5        nginx:latest   *:8081->80/tcp

 

 结论:

 以上两种方式均可实现动态扩缩容,方法二更简单一些!

 三、 访问测试

以上得知,服务,在集群任意节点中都可以访问!服务可以有多个副本动态扩缩容实现高可用!

在客户端看来,Swarm集群就是一个整体!

概念:

1. docker run      容器启动!不具有扩缩容功能!

2. docker service  服务!具有扩缩容功能,滚动更新!

 

posted @ 2021-03-04 14:50  西瓜君~  阅读(399)  评论(0编辑  收藏  举报