Docker 1.12 版本 Docker Swarm 集群

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docker 1.12 版本的新特性

（1）docker swarm：集群管理，子命令有 init, join, leave, update

（2）docker service：服务创建，子命令有 create, inspect, update, remove, tasks

（3）docker node：节点管理，子命令有 accept, promote, demote, inspect, update, tasks, ls, rm

（4）docker stack/deploy：试验特性，用于多应用部署，类似与 docker-compose 中的特性。

Docker 1.12 版本 Docker Swarm 集群

我在使用的时候还是测试版本，所以使用

wget -qO- https://test.docker.com/ | sh

进行安装配置

安装完毕以后:

[root@swarm-manager ~]# docker version
Client:
 Version:      1.12.0-rc2
 API version:  1.24
 Go version:   go1.6.2
 Git commit:   906eacd
 Built:        
 OS/Arch:      linux/amd64

Server:
 Version:      1.12.0-rc2
 API version:  1.24
 Go version:   go1.6.2
 Git commit:   906eacd
 Built:        
 OS/Arch:      linux/amd64

一、我们首先来看看 1.12 中新特性里面的内置 swarm 命令（swarmkit 采用 raft 协议构建集群）

[root@swarm-manager ~]# docker swarm --help

Usage: docker swarm COMMAND

Manage Docker Swarm

Options:
--help Print usage

Commands:
init Initialize a Swarm
join Join a Swarm as a node and/or manager
update Update the Swarm
leave Leave a Swarm
inspect Inspect the Swarm

Run 'docker swarm COMMAND --help' for more information on a command.

这里命令有 5 个

Commands:

init Initialize a Swarm

join Join a Swarm as a node and/or manager

update Update the Swarm

leave Leave a Swarm

inspect Inspect the Swarm

1. init 初始化，一个 Swarm 集群，执行效果：

[root@swarm-manager ~]# docker swarm init
Swarm initialized: current node (0vwpni05mew2j84i6gjet44iu) is now a manager.

这里显示初始化了一个 Swarm 集群，并把这机器做为管理节点。

[root@swarm-manager ~]#docker node ls
ID                           NAME                   MEMBERSHIP  STATUS  AVAILABILITY  MANAGER STATUS
0vwpni05mew2j84i6gjet44iu *  swarm-manager          Accepted    Ready   Active        Leader

执行 docker node ls 可以查看 Swarm 的集群情况（只能在 manager 中执行）

[root@swarm-manager ~]# netstat -lan|grep 2377

可以看到群集开放了一这个 2377 的端口。

默认绑定 0.0.0.0:2377，当然我们也可以使用 docker swarm init –listen-addr <MANAGER-IP>:<PORT> 进行绑定 ip

2377 这个端口是用于 Swarm 中 node 节点加入使使用的。

2. join 加入 Swarm 集群, 可加入做为 node 节点，也可加入作为管理节点。

[root@swarm-node-1 ~]#docker swarm join 10.6.0.140:2377
This node joined a Swarm as a worker.

这里在 node-1 里面执行了 join 命令，加入了 10.6.0.140 这个 manager 这个 Swarm 集群里

[root@swarm-manager ~]#docker node ls           
ID                           NAME                   MEMBERSHIP  STATUS  AVAILABILITY  MANAGER STATUS
0vwpni05mew2j84i6gjet44iu *  swarm-manager          Accepted    Ready   Active        Leader
4mqsmp0gzlqeicit98ce8wh2q    swarm-node-1           Accepted    Ready   Active

这里可以看到 node-1 已经加入到 swarm 的集群里面来了。

3. update 命令, 只提示 updated，具体作用尚不明白，应该是立刻刷新 swarm 的群集信息

[root@swarm-manager ~]#docker swarm update
Swarm updated.

4. leave 命令，离开 Swarm 集群，一个 docker 只能加入一个 node.

[root@swarm-node-1 ~]#docker swarm leave 10.6.0.140:2377

5. inspect 命令，查询 Swarm 集群的整体信息。（只能在 manager 中执行）

[root@swarm-manager ~]#docker swarm inspect
[
    {"ID": "c052zw5ll0ugw08shg2xf7ajp",
        "Version": {"Index": 11
        },
        "CreatedAt": "2016-06-23T02:09:18.935434519Z",
        "UpdatedAt": "2016-06-23T02:09:19.155114277Z",
        "Spec": {"Name": "default",
            "AcceptancePolicy": {"Policies": [
                    {"Role": "worker",
                        "Autoaccept": true
                    },
                    {"Role": "manager",
                        "Autoaccept": false
                    }
                ]
            },
            "Orchestration": {"TaskHistoryRetentionLimit": 10
            },
            "Raft": {"SnapshotInterval": 10000,
                "LogEntriesForSlowFollowers": 500,
                "HeartbeatTick": 1,
                "ElectionTick": 3
            },
            "Dispatcher": {"HeartbeatPeriod": 5000000000
            },
            "CAConfig": {"NodeCertExpiry": 7776000000000000
            }
        }
    }
]

二、接下来我们来看看 service 命令。

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

Usage:  docker service COMMAND

Manage Docker services

Options:
      --help   Print usage

Commands:
  create      Create a new service
  inspect     Inspect a service
  tasks       List the tasks of a service
  ls          List services
  rm          Remove a service
  scale       Scale one or multiple services
  update      Update a service

Run 'docker service COMMAND --help' for more information on a command.

1. docker create 命令，既创建一个服务。

[root@swarm-manager ~]#docker service create --help

Usage:  docker service create [OPTIONS] IMAGE [COMMAND] [ARG...]

Create a new service

Options:
      --constraint value             Placement constraints (default [])
      --endpoint-mode string         Endpoint mode(Valid values: VIP, DNSRR)
  -e, --env value                    Set environment variables (default [])
      --help                         Print usage
  -l, --label value                  Service labels (default [])
      --limit-cpu value              Limit CPUs (default 0.000)
      --limit-memory value           Limit Memory (default 0 B)
      --mode string                  Service mode (replicated or global) (default "replicated")
  -m, --mount value                  Attach a mount to the service
      --name string                  Service name
      --network value                Network attachments (default [])
  -p, --publish value                Publish a port as a node port (default [])
      --replicas value               Number of tasks (default none)
      --reserve-cpu value            Reserve CPUs (default 0.000)
      --reserve-memory value         Reserve Memory (default 0 B)
      --restart-condition string     Restart when condition is met (none, on_failure, or any)
      --restart-delay value          Delay between restart attempts (default none)
      --restart-max-attempts value   Maximum number of restarts before giving up (default none)
      --restart-window value         Window used to evalulate the restart policy (default none)
      --stop-grace-period value      Time to wait before force killing a container (default none)
      --update-delay duration        Delay between updates
      --update-parallelism uint      Maximum number of tasks updated simultaneously
  -u, --user string                  Username or UID
  -w, --workdir string               Working directory inside the container

docker service create 里面有非常多的参数。这里有很详细的使用说明。

下面我们来创建一个 service 试试看

首先 pull 一个 nginx 镜像下来用于测试

[root@swarm-manager ~]#docker pull nginx

创建 2 个 nginx :

[root@swarm-manager ~]#docker service create --name nginx --replicas 2 -p 80:80/tcp nginx

使用 docker service ls 可查看服务启动情况。

[root@swarm-manager ~]#docker service ls
ID            NAME   REPLICAS  IMAGE  COMMAND
1b9a58mlz330  nginx  1/2       nginx

使用 tasks 命令可查看 nginx 的情况。

[root@swarm-manager ~]#docker service tasks nginx
ID                         NAME     SERVICE  IMAGE  LAST STATE           DESIRED STATE  NODE
56er48j3hin9ysdi3sb1chbn1  nginx.1  nginx    nginx  Preparing 2 minutes  Running        swarm-node-1
e7vtvpkbstznoi8ogihaao1f5  nginx.2  nginx    nginx  Running 2 minutes    Running        swarm-manager

这里显示 swarm-node-1 节点中 last state 的状态为 preparing .

原因是 swarm-node-1 节点并没有 nginx 的镜像

在 node-1 节点 pull nginx 镜像。

[root@swarm-node-1 ~]#docker pull nginx

node-1 节点 pull 完毕以后，在使用 service ls 查看，服务已经自动启动了。

Swarm 模式下的引擎拥有自组织与自修复特性，意味着它们能够识别我们定义的应用，并在出现差错时持续检查并修复环境。

举例来说，如果大家关闭某台运行有 Nginx 实例的设备，则另一节点上会自动启动一套新的容器。

如果关闭 Swarm 内半数设备所使用的网络交换机，则另外一半设备会顶替而上，接管对应工作负载。

[root@swarm-manager ~]#docker service ls
ID            NAME   REPLICAS  IMAGE  COMMAND
1b9a58mlz330  nginx  2/2       nginx

[root@swarm-manager ~]#docker service tasks nginx
ID                         NAME     SERVICE  IMAGE  LAST STATE          DESIRED STATE  NODE
56er48j3hin9ysdi3sb1chbn1  nginx.1  nginx    nginx  Running 32 minutes  Running        swarm-node-1
e7vtvpkbstznoi8ogihaao1f5  nginx.2  nginx    nginx  Running 32 minutes  Running        swarm-manager

2. docker service scale 命令，这个命令是批量生成已有容器。

直接对 nginx=10 既可让 nginx 的容器生成 10 个。

[root@swarm-manager ~]#docker service scale nginx=10
nginx scaled to 10

使用 tasks 可以看到，已经在 2 个节点中生成了 10 个 nginx 容器

[root@swarm-manager ~]#docker service tasks nginx
ID                         NAME      SERVICE  IMAGE  LAST STATE            DESIRED STATE  NODE
56er48j3hin9ysdi3sb1chbn1  nginx.1   nginx    nginx  Running 43 minutes    Running        swarm-node-1
e7vtvpkbstznoi8ogihaao1f5  nginx.2   nginx    nginx  Running 43 minutes    Running        swarm-manager
9vqxcmskj1nawo8wl0fqr32j2  nginx.3   nginx    nginx  Preparing 20 seconds  Running        swarm-manager
0vbqoyestm7ob6r1zq9jwj6il  nginx.4   nginx    nginx  Running 20 seconds    Running        swarm-node-1
13jf9mkl4k5e57pq4hoeb68ru  nginx.5   nginx    nginx  Running 20 seconds    Running        swarm-node-1
a0tk6ni6a02diuo5u3t870qk7  nginx.6   nginx    nginx  Running 20 seconds    Running        swarm-manager
cwplvo5wfqp3rn5ynvxv9wv90  nginx.7   nginx    nginx  Running 20 seconds    Running        swarm-manager
7feil5xqc5hdkseasthkq2nyx  nginx.8   nginx    nginx  Running 20 seconds    Running        swarm-node-1
8jt5yovxoz7t89edinb9ydao1  nginx.9   nginx    nginx  Starting 20 seconds   Running        swarm-node-1
dst4ydun1upham0o7e8a9hj3w  nginx.10  nginx    nginx  Running 20 seconds    Running        swarm-manager

当我们想缩容时间，也可以使用 scale nginx=2 让容器变成 2 个。

[root@swarm-manager ~]#docker service scale nginx=2
nginx scaled to 2

在运行 nginx=2 时可以看到容器已经缩小为 2 个。

当我们使用 docker ps 查看，会发现容器被 stop 而非 rm。

当我们使用 docker service rm nginx 的时候，所有的容器都会被删除，请注意。

[root@swarm-manager ~]#docker service tasks nginx
ID                         NAME     SERVICE  IMAGE  LAST STATE          DESIRED STATE  NODE
0vbqoyestm7ob6r1zq9jwj6il  nginx.4  nginx    nginx  Running 12 minutes  Running        swarm-node-1
13jf9mkl4k5e57pq4hoeb68ru  nginx.5  nginx    nginx  Running 12 minutes  Running        swarm-node-1

3. docker service update 命令。可对服务的启动参数进行更新 / 修改。

上面我们新建了一个服务，命令为：

[root@swarm-manager ~]#docker service create --name nginx --replicas 2 -p 80:80/tcp nginx

如果我们先新加入了一个 node 想让 nginx 分布在 3 个 node 上面，我们可以使用 update 命令。

[root@swarm-manager ~]#docker service update --replicas 3 nginx
nginx

更新完毕以后我们可以查看到 REPLICAS 已经变成 3/3

[root@swarm-manager ~]#docker service ls
ID            NAME   REPLICAS  IMAGE  COMMAND
1b9a58mlz330  nginx  3/3       nginx

docker service update 命令，也可用于直接升级镜像等。

[root@swarm-manager ~]#docker service tasks nginx
ID                         NAME     SERVICE  IMAGE  LAST STATE           DESIRED STATE  NODE
0vbqoyestm7ob6r1zq9jwj6il  nginx.4  nginx    nginx  Running 41 minutes   Running        swarm-node-1
340e1u31vadq3jtebzeddmatt  nginx.5  nginx    nginx  Preparing 5 seconds  Running        swarm-manager

上面我们使用了 nginx 镜像启动了任务。使用 update –image 可直接对 image 进行更新。

[root@swarm-manager ~]#docker service update --image nginx:new nginx 
nginx

可以看到 IMAGE 已经变成 nginx:new

[root@swarm-manager ~]#docker service tasks nginx
ID                         NAME     SERVICE  IMAGE      LAST STATE          DESIRED STATE  NODE
2ba3utpk6icf0w449kcwgxmnm  nginx.4  nginx    nginx:new  Running 49 seconds  Running        swarm-manager
5wmmneiueeool09fs8d2g1ncq  nginx.5  nginx    nginx:new  Running 49 seconds  Running        swarm-node-1

挂载目录, mount


docker service create --mount type=bind,target=/container_data/,source=/host_data/

例 - 本地目录：target = 容器里面的路径，source = 本地硬盘路径
docker service create --name nginx --mount type=bind,target=/usr/share/nginx/html/,source=/opt/web/ --replicas 2 --publish 80:80/tcp nginx


docker service create --mount type=volume,source=<VOLUME-NAME>,target=<CONTAINER-PATH>,volume-driver=<DRIVER>,

例 - 挂载 volume 卷：source  =  volume 名称 ,  traget = 容器里面的路径
docker service create --name nginx --mount type=volume,source=myvolume,target=/usr/share/nginx/html,volume-driver=local --replicas 2 --publish 80:80/tcp nginx

三、下面是 node , node 命令用于节点管理:

[root@swarm-manager ~]#docker node --help

Usage:  docker node COMMAND

Manage Docker Swarm nodes

Options:
      --help   Print usage

Commands:
  accept      Accept a node in the swarm
  demote      Demote a node from manager in the swarm
  inspect     Inspect a node in the swarm
  ls          List nodes in the swarm
  promote     Promote a node to a manager in the swarm
  rm          Remove a node from the swarm
  tasks       List tasks running on a node
  update      Update a node

Run 'docker node COMMAND --help' for more information on a command.