Docker Swarm

Docker Swarm

docker swarm init --advertise-addr 192.168.122.171  # 初始化创建一个集群
docker  network ls # 查看网络
docker node ls # 查看节点 只能在主节点上查看
docker swarm join-token worker # 生成工作节点令牌命令
docker swarm join-token manager # 生成主节点令牌命令

双主双从，不合理，Raft原则：保证大多数的服务器可用，

当关闭一个主节点时：

[root@node1 ~]# docker node ls
Error response from daemon: rpc error: code = 4 desc = context deadline exceeded

docker swarm leave  # 让node3节点离开 
[root@node4 ~]# docker node ls
ID                           HOSTNAME  STATUS  AVAILABILITY  MANAGER STATUS
mh1cxxjetuk4odh51az2vlzmr    node3     Down    Active        
ngi2kf7g0fyxjvvqoqtydhba5    node2     Ready   Active        
pi76wh4e6m2ijwd9t1r2b8zoo *  node4     Ready   Active        Reachable
wno67f1ibrfrmy502hx49mw2v    node1     Ready   Active        Leader

# 将node3 也设置为manager

[root@node3 ~]# docker node ls
ID                           HOSTNAME  STATUS  AVAILABILITY  MANAGER STATUS
mh1cxxjetuk4odh51az2vlzmr    node3     Down    Active        
ngi2kf7g0fyxjvvqoqtydhba5    node2     Ready   Active        
pi76wh4e6m2ijwd9t1r2b8zoo    node4     Ready   Active        Reachable
wno67f1ibrfrmy502hx49mw2v    node1     Ready   Active        Leader
zfsh8qbgvnlx8lume3svwnez5 *  node3     Ready   Active        Reachable

# 让node4 挂掉

[root@node3 ~]# docker node ls
ID                           HOSTNAME  STATUS  AVAILABILITY  MANAGER STATUS
mh1cxxjetuk4odh51az2vlzmr    node3     Down    Active        
ngi2kf7g0fyxjvvqoqtydhba5    node2     Ready   Active        
pi76wh4e6m2ijwd9t1r2b8zoo    node4     Down    Active        Unreachable
wno67f1ibrfrmy502hx49mw2v    node1     Ready   Active        Leader
zfsh8qbgvnlx8lume3svwnez5 *  node3     Ready   Active        Reachable

docker node ls # 还是可以查到，说明集群还是可用的，这就说明了Raft原则



docker service COMMAND
> Commands:
>   create      Create a new service
>   inspect     Display detailed information on one or more services
>   ls          List services
>   ps          List the tasks of a service
>   rm          Remove one or more services
>   scale       Scale one or multiple replicated services
>   update      Update a service

docker service create -p 8888:80 --name mynginx nginx
[root@node1 ~]# docker service ps mynginx  #  查看服务进程
ID            NAME       IMAGE         NODE   DESIRED STATE  CURRENT STATE           ERROR  PORTS
woz6eqmtw55e  mynginx.1  nginx:latest  node4  Running        Running 37 seconds ago         

docker-compose up 启动的一个项目，还是单机的，这是不现实的，
只有集群才可以
redis 3份 容器
三个redis 不一定在同一个服务器上
容器变成服务，服务==》 副本
redis服务 =》 10个副本 同时开启10个redis容器

扩缩容：

# update 方式
[root@node1 ~]# docker service update --replicas 3 mynginx
mynginx
[root@node1 ~]# docker service ps mynginx
ID            NAME       IMAGE         NODE   DESIRED STATE  CURRENT STATE            ERROR  PORTS
woz6eqmtw55e  mynginx.1  nginx:latest  node4  Running        Running 4 minutes ago         
27hlhqn6h21q  mynginx.2  nginx:latest  node2  Running        Preparing 9 seconds ago       
l4di878yi5m9  mynginx.3  nginx:latest  node1  Running        Preparing 9 seconds ago 
[root@node1 ~]# docker service update --replicas 2 mynginx
mynginx
[root@node1 ~]# docker service ps mynginx
ID            NAME       IMAGE         NODE   DESIRED STATE  CURRENT STATE          ERROR  PORTS
27hlhqn6h21q  mynginx.2  nginx:latest  node2  Running        Running 3 minutes ago         
l4di878yi5m9  mynginx.3  nginx:latest  node1  Running        Running 3 minutes ago    

# 另一种方式 scale
[root@node1 ~]# docker service scale mynginx=6
mynginx scaled to 6
# 查看mynginx的服务进程
[root@node1 ~]# docker service ps mynginx
ID            NAME       IMAGE         NODE   DESIRED STATE  CURRENT STATE             ERROR  PORTS
yso77fxq2igf  mynginx.1  nginx:latest  node4  Running        Running 12 seconds ago         
27hlhqn6h21q  mynginx.2  nginx:latest  node2  Running        Running 4 minutes ago         
l4di878yi5m9  mynginx.3  nginx:latest  node1  Running        Running 4 minutes ago         
w52awqqvvrox  mynginx.4  nginx:latest  node3  Running        Preparing 14 seconds ago       
u8i43jr046sm  mynginx.5  nginx:latest  node3  Running        Preparing 14 seconds ago       
ddvpu4olognu  mynginx.6  nginx:latest  node1  Running        Running 13 seconds ago          

移除一个服务

# 移除一个服务
docker service rm mynginx

访问：

访问任意一个节点，都可以得到结果，即使这个节点上真实没有运行，但是他们是一个整体集群