create a swarm

create a swarm

• 创建一个新的集群

    docker swarm init --advertise-addr <MANAGER-IP>

• Run docker info to view the current state of the swarm:

    $ docker info
    Containers: 2
    Running: 0
    Paused: 0
    Stopped: 2
    ..snip...
    Swarm: active
    NodeID: dxn1zf6l61qsb1josjja83ngz
    Is Manager: true
    Managers: 1
    Nodes: 1
    ...snip...

[root@centos5 ~]# docker node ls
ID                            HOSTNAME            STATUS              AVAILABILITY        MANAGER STATUS
ip2fs5kkfpllyexal8pxuxnlq     centos4             Ready               Active              
t7998hft3zw479evc7lr8irx2 *   centos5             Ready               Active              Leade

• run the following command on a manager node to retrieve the join command for a worker

    docker swarm join-token worker
    [root@centos5 ~]# docker swarm join-token worker
    To add a worker to this swarm, run the following command:

    docker swarm join --token SWMTKN-1-1705vcetk9pgd3nb9zph2izwtcudq1ajeh7b13wqcst46epk18-bltg74jq3ql7zrswirt6xhwm3 10.173.38.40:2377

• use command to create a severvice:

    docker service create --replicas 1 --name helloworld alpine ping docker.com

• Run docker service inspect --pretty to display the details about a service in an easily readable format.

[root@centos5 ~]# docker service inspect --pretty helloworld

ID:		vk639rdtes0pw8anp7dxnznzu
Name:		helloworld
Service Mode:	Replicated
Replicas:	1
Placement:
UpdateConfig:
Parallelism:	1
On failure:	pause
Monitoring Period: 5s
Max failure ratio: 0
Update order:      stop-first
RollbackConfig:
Parallelism:	1
On failure:	pause
Monitoring Period: 5s
Max failure ratio: 0
Rollback order:    stop-first
ContainerSpec:
Image:		alpine:latest@sha256:1072e499f3f655a032e88542330cf75b02e7bdf673278f701d7ba61629ee3ebe
Args:		ping docker.com 
Resources:
Endpoint Mode:	vip

• Run docker service ps to see which nodes are running the service:

[root@centos5 ~]# docker service ps helloworld
ID                  NAME                IMAGE               NODE                DESIRED STATE       CURRENT STATE           ERROR               PORTS
zgeljyk5fqf6        helloworld.1        alpine:latest       centos5             Running             Running 8 minutes ago                       

*Run the following command to change the desired state of the service running in the swarm:

$ docker service scale <SERVICE-ID>=<NUMBER-OF-TASKS>

• Now you can update the container image for redis. The swarm manager applies the update to nodes according to the UpdateConfig policy:

docker service update --image redis:3.0.7 redis