Docker1.12新特性之集群

在Docker1.12版本中，一个大的功能点是swarm集群（基于swarmkit项目），通过docker命令可以直接实现docker-engine相互发现，并组建成为一个容器集群。有关集群的docker命令如下：

（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，用于多应用部署下面在一个三节点环境中，针对各个命令进行试用，详细展开说明

1、swarm

swarm命令用于集群管理，子命令如下：

[root@host1 ~]# docker swarm --help
Usage:  dockerswarmCOMMAND
ManageDockerSwarm
Options:
      --help  Printusage
Commands:
  init        Initialize a Swarm.
  join        Join a Swarmas a nodeand/or manager.
  update      updatetheSwarm.
  leave      Leave a Swarm.
  inspect    InspecttheSwarm
Run 'docker swarm COMMAND --help' for moreinformationon a command.

可以看到，提供了init、join、update、leave、inspect命令

（1）swarm init命令用于初始化一个集群

[root@host1 ~]# docker swarm init --help
Usage:  dockerswarminit [OPTIONS]
Initialize a Swarm.
Options:
      --auto-acceptvalue  Autoacceptancepolicy (worker, manager, or none)
      --force-new-cluster  Forcecreate a new clusterfromcurrentstate.
      --help                Printusage
      --listen-addrvalue  Listenaddress (default 0.0.0.0:2377)
      --secretstring      Setsecretvalueneededto acceptnodesintocluster

在第一个节点上运行init命令初始化一个集群，初始化完成后会监听2377端口，接受其他节点的加入请求

[root@host1 ~]# docker swarm init
Swarminitialized: currentnode (6mjmescd8473lh6jpvmx2khkq) is now a manager.

（2）swarm join命令用于加入一个现有集群

[root@host1 ~]# docker swarm join --help
Usage:  dockerswarmjoin [OPTIONS] HOST:PORT
Join a Swarmas a nodeand/or manager.
Options:
      --ca-hashstring      HashoftheRootCertificateAuthoritycertificateusedfor trustedjoin
      --help                Printusage
      --listen-addrvalue  Listenaddress (default 0.0.0.0:2377)
      --manager            Try joiningas a manager.
      --secretstring      Secretfor nodeacceptance

在第二个、第三个节点上通过join命令加入集群

[root@host2 ~]# docker swarm join 186.100.40.90:2377
This nodejoined a Swarmas a worker.
[root@host3 ~]# docker swarm join 186.100.40.90:2377
This nodejoined a Swarmas a worker.

在第一个节点上，通过docker node ls查看节点信息

[root@host1 ~]# docker node ls
ID                          NAME  MEMBERSHIP  STATUS  AVAILABILITY  MANAGERSTATUS  LEADER
3xto6bh4htx7thj7b222datfd    host2  Accepted    Ready  Active                        
6mjmescd8473lh6jpvmx2khkq *  host1  Accepted    Ready  Active        Reachable      Yes
bwkk0n044fuod36dvghi9jbkv    host3  Accepted    Ready  Active

可以看到当前集群中有3个节点，Manager节点为host1，由于当前只有一个manager，所以这一节点也为是leader（swarmkit采用raft协议构建集群）

（3）swarm leave命令由于离开集群

（4）swarm inspect命令用于查看集群详细信息

[root@host1 ~]# docker swarm inspect
[
    {
        "ID": "90wkw2fmy0x5fjlh0mtuhtkrd",
        "Version": {
            "Index": 11
        },
        "CreatedAt": "2016-06-19T12:47:40.260925387Z",
        "UpdatedAt": "2016-06-19T12:47:40.665401298Z",
        "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
            }
        }
    }
]

2、service

通过service命令可以管理一个服务，子命令如下：

[root@host1 ~]# docker service --help
Usage:  dockerserviceCOMMAND
ManageDockerservices
Options:
      --help  Printusage
Commands:
  create      Create a new service
  inspect    Inspect a service
  tasks      Listthetasksof a service
  ls          Listservices
  rm          Remove a service
  scale      Scaleoneor multipleservices
  update      Update a service
Run 'docker service COMMAND --help' for moreinformationon a command.

（1）service create命令用于创建一个服务

[root@host1 ~]# docker service create –help
Usage:  dockerservicecreate [OPTIONS] IMAGE [COMMAND] [ARG...]
Create a new service
Options:
      --constraintvalue            Placementconstraints (default [])
      --endpoint-modestring        Endpointmode(Validvalues: VIP, DNSRR)
  -e, --envvalue                    Setenvironmentvariables (default [])
      --help                        Printusage
  -l, --labelvalue                  Servicelabels (default [])
      --limit-cpuvalue              LimitCPUs
      --limit-memoryvalue          LimitMemory
      --modestring                  Servicemode (replicatedor global) (default"replicated")
  -m, --mountvalue                  Attach a mountto theservice
      --namestring                  Servicename
      --networkvalue                Networkattachments (default [])
  -p, --publishvalue                Publish a portas a nodeport (default [])
      --replicasvalue              Numberoftasks (default none)
      --reserve-cpuvalue            ReserveCPUs
      --reserve-memoryvalue        ReserveMemory
      --restart-conditionstring    Restartwhenconditionis met (none, on_failure, orany)
      --restart-delayvalue          Delaybetweenrestartattempts (default none)
      --restart-max-attemptsvalue  Maximumnumberofrestartsbeforegivingup (default none)
      --restart-windowvalue        Windowusedto evalulatetherestartpolicy (default none)
      --stop-grace-periodvalue      Timeto waitbeforeforcekilling a container (default none)
      --update-delayduration        Delaybetweenupdates
      --update-parallelismuint      Maximumnumberoftasksupdatedsimultaneously (default1)
  -u, --userstring                  Usernameor UID
  -w, --workdirstring              Workingdirectoryinsidethecontainer

在参数中有两个比较重要的参数： * replicas用于描述服务对应的实例数 * mode用来描述服务的类型，replicated多实例类型，global全局服务类型（在每一个节点上都会创建）

在第一个节点上，通过create命令创建服务：

[root@host1 ~]# docker service create --name test_service --replicas 2 busybox ping 186.100.40.1
et1i181ni4dj2ocm1l4frbqzm

（2）service ls命令用户查看service列表

[root@host1 ~]# docker service ls
ID            NAME          SCALE  IMAGE    COMMAND
et1i181ni4dj  test_service  2      busybox  ping 186.100.40.1

（3）service tasks可以查看service对应的任务

[root@host1 ~]# docker service tasks test_service
ID                        NAME            SERVICE      IMAGE    LASTSTATE              DESIREDSTATE  NODE
1yewid0xbviyggyvjv10adjrs  test_service.1  test_service  busybox  RunningAbout a minute  Running        host3
9l4z9aqlg9iwums14yxu0lym7  test_service.2  test_service  busybox  RunningAbout a minute  Running        host1

可以看到，刚才创建的service对应的2个实例分别在host3和host1上

（4）service update可以对服务的参数进行更新

对刚才创建的service实力数目进行更新

[root@host1 ~]# docker service update --replicas 3 test_service
test_service
[root@host1 ~]# docker service tasks test_service
ID                        NAME            SERVICE      IMAGE    LASTSTATE          DESIREDSTATE  NODE
1yewid0xbviyggyvjv10adjrs  test_service.1  test_service  busybox  Running 5 minutes  Running        host3
9l4z9aqlg9iwums14yxu0lym7  test_service.2  test_service  busybox  Running 5 minutes  Running        host1
emnuxg8sb37hbxbpdt63mpy1a  test_service.3  test_service  busybox  Running 18 seconds  Running        host2

（5）service inspect命令用户查看service详细信息

[root@host1 ~]# docker service inspect test_service
[
    {
        "ID": "et1i181ni4dj2ocm1l4frbqzm",
        "Version": {
            "Index": 33
        },
        "CreatedAt": "2016-06-19T13:07:29.549242777Z",
        "UpdatedAt": "2016-06-19T13:12:23.210552545Z",
        "Spec": {
            "Name": "test_service",
            "TaskTemplate": {
                "ContainerSpec": {
                    "Image": "busybox",
                    "Args": [
                        "ping",
                        "186.100.40.1"
                    ]
                },
                "Resources": {
                    "Limits": {},
                    "Reservations": {}
                },
                "RestartPolicy": {
                    "Condition": "any",
                    "MaxAttempts": 0
                },
                "Placement": {}
            },
            "Mode": {
                "Replicated": {
                    "Replicas": 3
                }
            },
            "UpdateConfig": {
                "Parallelism": 1
            },
            "EndpointSpec": {
                "Mode": "vip"
            }
        },
        "Endpoint": {
            "Spec": {}
        }
    }
]

3、node

node命令用户节点管理，比如将一个节点变为manager节点、同意节点加入请求等。

[root@host1 ~]# docker node --help
Usage:  dockernodeCOMMAND
ManageDockerSwarmnodes
Options:
      --help  Printusage
Commands:
  accept      Accept a nodein theswarm
  demote      Demote a nodefrommanagerin theswarm
  inspect    Inspect a nodein theswarm
  ls          Listnodesin theswarm
  promote    Promote a nodeto a managerin theswarm
  rm          Remove a nodefromtheswarm
  tasks      Listtasksrunningon a node
  update      Update a node
Run 'docker node COMMAND --help' for moreinformationon a command.

（1）node accept

accpet命令用户同意节点加入请求，在初始化swarm集群时候通过–auto-accept可以指定节点默认加入的较色，如果为none的话，需要通过accpet命令同意加入节点，成为worker节点重新初始化三节点，集群初始化时，采用–auto-accept=none，最终可以看到新加入的两个节点MEMBERSHIP为Pending

[root@host1 ~]# docker node ls
ID                          NAME  MEMBERSHIP  STATUS  AVAILABILITY  MANAGERSTATUS  LEADER
15wyq8vc1vxe7r4n3yyl0p93j *  host1  Accepted    Ready    Active        Reachable      Yes
2fh91rbwtj2xosqixzlc7s3mg          Pending    Unknown  Active                        
5okhpif49b4d6byohpdr4vdmw          Pending    Unknown  Active

通过accept命令同意节点加入：

[root@host1 ~]# docker node accept 2fh91rbwtj2xosqixzlc7s3mg
2fh91rbwtj2xosqixzlc7s3mg
[root@host1 ~]# docker node ls
ID                          NAME  MEMBERSHIP  STATUS  AVAILABILITY  MANAGERSTATUS  LEADER
15wyq8vc1vxe7r4n3yyl0p93j *  host1  Accepted    Ready    Active        Reachable      Yes
2fh91rbwtj2xosqixzlc7s3mg    host3  Accepted    Ready    Active                        
5okhpif49b4d6byohpdr4vdmw          Pending    Unknown  Active  
[root@host1 ~]# docker node accept 5okhpif49b4d6byohpdr4vdmw
5okhpif49b4d6byohpdr4vdmw
5okhpif49b4d6byohpdr4vdmw attemptingto accept a nodein theswarm.
[root@host1 ~]# docker node ls
ID                          NAME  MEMBERSHIP  STATUS  AVAILABILITY  MANAGERSTATUS  LEADER
15wyq8vc1vxe7r4n3yyl0p93j *  host1  Accepted    Ready  Active        Reachable      Yes
2fh91rbwtj2xosqixzlc7s3mg    host3  Accepted    Ready  Active                        
5okhpif49b4d6byohpdr4vdmw    host2  Accepted    Ready  Active

（2）node promote命令用于将worker节点提升为manager节点，用户manager的HA

[root@host1 ~]# docker node promote 2fh91rbwtj2xosqixzlc7s3mg
2fh91rbwtj2xosqixzlc7s3mg
2fh91rbwtj2xosqixzlc7s3mg attemptingto promote a nodeto a managerin theswarm.
[root@host1 ~]# docker node ls
ID                          NAME  MEMBERSHIP  STATUS  AVAILABILITY  MANAGERSTATUS  LEADER
15wyq8vc1vxe7r4n3yyl0p93j *  host1  Accepted    Ready  Active        Reachable      Yes
2fh91rbwtj2xosqixzlc7s3mg    host3  Accepted    Ready  Active        Reachable      
5okhpif49b4d6byohpdr4vdmw    host2  Accepted    Ready  Active  
[root@host1 ~]# docker node promote 5okhpif49b4d6byohpdr4vdmw
5okhpif49b4d6byohpdr4vdmw
5okhpif49b4d6byohpdr4vdmw attemptingto promote a nodeto a managerin theswarm.
[root@host1 ~]# docker node ls
ID                          NAME  MEMBERSHIP  STATUS  AVAILABILITY  MANAGERSTATUS  LEADER
15wyq8vc1vxe7r4n3yyl0p93j *  host1  Accepted    Ready  Active        Reachable      Yes
2fh91rbwtj2xosqixzlc7s3mg    host3  Accepted    Ready  Active        Reachable      
5okhpif49b4d6byohpdr4vdmw    host2  Accepted    Ready  Active        Reachable

（3）node demote命令用户将manger节点变为worker节点

[root@host1 ~]# docker node demote 15wyq8vc1vxe7r4n3yyl0p93j
15wyq8vc1vxe7r4n3yyl0p93j
15wyq8vc1vxe7r4n3yyl0p93j attemptingto demote a managerin theswarm.
[root@host1 ~]# docker node ls
Errorresponsefromdaemon: rpcerror: code = 4 desc = contextdeadlineexceeded

可以看到变为worker节点以后，就无法再此节点上对集群进行管理

[root@host2 ~]# docker node ls
ID                          NAME  MEMBERSHIP  STATUS  AVAILABILITY  MANAGERSTATUS  LEADER
15wyq8vc1vxe7r4n3yyl0p93j    host1  Accepted    Ready  Active                        
2fh91rbwtj2xosqixzlc7s3mg    host3  Accepted    Ready  Active        Reachable      Yes
5okhpif49b4d6byohpdr4vdmw *  host2  Accepted    Ready  Active        Reachable

可以看到此时，host2已经变为了leader

（4）node inspect查看节点详细信息

（5）node ls查看节点列表

（6）node rm删除一个节点

（7）node tasks可以查看节点上运行的任务task

（8）node update可以更新一个节点

[root@host2 ~]# docker node update --help

Usage:    docker node update [OPTIONS] NODE

Update a node

Options:
      --availability string   Availability of the node (active/pause/drain)
      --help                  Print usage
      --label-add list        Add or update a node label (key=value) (default [])
      --label-rm list         Remove a node label if exists (default [])
      --role string           Role of the node (worker/manager)

4、stack/deploy

这两个命令都是experiment阶段，用来部署一个STACK，一个STACK可以描述多个service。在创建Stack前，需要通过compose.yml文件描述一个组应用，然后再用compose bundle产生一个dsb文件，用户stack的创建。

[root@host2 ~]# docker stack --help

Usage:    docker stack COMMAND

Manage Docker stacks

Options:
      --help   Print usage

Commands:
  deploy      Deploy a new stack or update an existing stack
  ls          List stacks
  ps          List the tasks in the stack
  rm          Remove the stack
  services    List the services in the stack

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

5、总结

Docker1.12通过swarm实现了容器集群，在集群之上可以service命令创建一个服务，实现服务的多实例。在服务之上，通过stack可以描述一组服务，最终实现一个大系统的部署。可见，Docker在公司在下一盘很大的棋，从镜像生态到容器引擎，从容器引擎到容器集群，Anything is possible in Docker。

posted @ 2019-04-04 17:34 liuxinyu123 阅读(144) 评论(0) 收藏举报

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