Swarm是Docker公司推出的用来管docker的一个集群管理软件。
Swarm 可以在多个服务器或主机上创建容器集群服务。
swarm 的架构图
Swarm是典型的master-slave结构，通过发现服务来选举manager。
Swarm的几个关键概念
swarm ：一个 swarm 由多个 Docker 主机组成，这些主机在 Warm 模式下运行，充当管理器（管理成员资格和委派）和工作线程（运行 swarm 服务）。Docker 引擎中嵌入的集群管理和编排功能是使用 swarmkit 构建的。Swarmkit 是一个单独的项目，它实现了 Docker 的编排层，并直接在 Docker 中使用。
node ：node是参与swarm的 Docker 引擎的实例。，我们可以在单台服务器上运行一个或多个节点。
service ：是要在管理器或工作器节点上执行的任务的定义。它是 swarm系统的中心结构和用户主要与 swarm的互动。创建服务时，您可以指定要使用的容器映像以及哪个容器映像 要在正在运行的容器中执行的命令。
task ：任务是一个正在运行的容器，它是 swarm服务的一部分，由 swarm管理，而不是独立的容器。
1.节点的工作原理
2.服务的工作原理
3.swarm 模式如何接受服务创建请求和将任务计划到工作器节点。
4.复制服务和全局服务
swarm的调度策略
swarm在调度节点运行容器的时候，会根据指定的策略来计算最适合运行容器的节点，目前支持的策略有：spread，binpack，random。
1.Random
随机选择一个Node来运行容器，一般用作调试。
2.Spread
Spread策略会选择运行容器最少的那台节点来运行新的容器，会使得容器均衡的分布在集群中的各个节点上运行，一旦一个节点挂掉了只会损失少部分的容器。
3.Binpack
Binpack策略最大化的避免容器碎片化，就是说binpack策略尽可能的把还未使用的节点留给需要更大空间的容器运行，尽可能的把容器运行在一个节点上面。
Swarm集群部署
ip、hostname、role规划
ip | hostname | role |
192.168.1.140 | manger | manger |
192.168.1.123 | node1 | node |
192.168.1.125 | node2 | node |
第一步：前期的准备工作
1.修改主机名
[root@manager ~]# hostnamectl set-hostname manager
[root@node1 ~]# hostnamectl set-hostname node1
[root@node2 ~]# hostnamectl set-hostname node2
2.配置hosts文件
cat /etc/hosts
127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4
::1 localhost localhost.localdomain localhost6 localhost6.localdomain6
192.168.1.140 manager
192.168.1.123 node1
192.168.1.125 node2
3.关闭防火墙
systemctl stop firewalld && systemctl disable firewalld
4.关闭seLinux
vim /etc/selinux/config
SELINUX=disabled
5.已经安装docker环境
[root@manger ~]# docker version
Client: Docker Engine - Community
Version: 24.0.4
API version: 1.43
Go version: go1.20.5
Git commit: 3713ee1
Built: Fri Jul 7 14:54:21 2023
OS/Arch: linux/amd64
Context: default
Server: Docker Engine - Community
Engine:
Version: 24.0.4
API version: 1.43 (minimum version 1.12)
Go version: go1.20.5
Git commit: 4ffc614
Built: Fri Jul 7 14:53:26 2023
OS/Arch: linux/amd64
Experimental: false
containerd:
Version: 1.6.21
GitCommit: 3dce8eb055cbb6872793272b4f20ed16117344f8
runc:
Version: 1.1.7
GitCommit: v1.1.7-0-g860f061
docker-init:
Version: 0.19.0
GitCommit: de40ad0第二步：创建Swarm集群并且添加节点
[root@manger ~]# docker swarm init --advertise-addr 192.168.1.140
Swarm initialized: current node (b5xsdqqky3kzuav4x9i3ks1y3) is now a manager.
To add a worker to this swarm, run the following command:
docker swarm join --token SWMTKN-1-3lsbxnxitex8rvuebocuyvsexu0rp3x14njplny0bjxmdj203e-5zi94bk6j2qr4fiy3qnq33xfs 192.168.1.140:2377
To add a manager to this swarm, run 'docker swarm join-token manager' and follow the instructions.
[root@node1 ~]# docker swarm join --token SWMTKN-1-3lsbxnxitex8rvuebocuyvsexu0rp3x14njplny0bjxmdj203e-5zi94bk6j2qr4fiy3qnq33xfs 192.168.1.140:2377
This node joined a swarm as a worker.
[root@node2 ~]# docker swarm join --token SWMTKN-1-3lsbxnxitex8rvuebocuyvsexu0rp3x14njplny0bjxmdj203e-5zi94bk6j2qr4fiy3qnq33xfs 192.168.1.140:2377
This node joined a swarm as a worker.第三步：查看集群的相关信息
[root@manger ~]# docker info
Client: Docker Engine - Community
Version: 24.0.4
Context: default
Debug Mode: false
Plugins:
buildx: Docker Buildx (Docker Inc.)
Version: v0.11.1
Path: /usr/libexec/docker/cli-plugins/docker-buildx
compose: Docker Compose (Docker Inc.)
Version: v2.19.1
Path: /usr/libexec/docker/cli-plugins/docker-compose
Server:
Containers: 0
Running: 0
Paused: 0
Stopped: 0
Images: 0
Server Version: 24.0.4
Storage Driver: overlay2
Backing Filesystem: xfs
Supports d_type: true
Using metacopy: false
Native Overlay Diff: true
userxattr: false
Logging Driver: json-file
Cgroup Driver: cgroupfs
Cgroup Version: 1
Plugins:
Volume: local
Network: bridge host ipvlan macvlan null overlay
Log: awslogs fluentd gcplogs gelf journald json-file local logentries splunk syslog
Swarm: active
NodeID: b5xsdqqky3kzuav4x9i3ks1y3
Is Manager: true
ClusterID: pje9ziqpdyl2mwftvvorshltl
Managers: 1
Nodes: 3
Default Address Pool: 10.0.0.0/8
SubnetSize: 24
Data Path Port: 4789
Orchestration:
Task History Retention Limit: 5
Raft:
Snapshot Interval: 10000
Number of Old Snapshots to Retain: 0
Heartbeat Tick: 1
Election Tick: 10
Dispatcher:
Heartbeat Period: 5 seconds
CA Configuration:
Expiry Duration: 3 months
Force Rotate: 0
Autolock Managers: false
Root Rotation In Progress: false
Node Address: 192.168.1.140
Manager Addresses:
192.168.1.140:2377
Runtimes: io.containerd.runc.v2 runc
Default Runtime: runc
Init Binary: docker-init
containerd version: 3dce8eb055cbb6872793272b4f20ed16117344f8
runc version: v1.1.7-0-g860f061
init version: de40ad0
Security Options:
seccomp
Profile: builtin
Kernel Version: 3.10.0-1160.88.1.el7.x86_64
Operating System: CentOS Linux 7 (Core)
OSType: linux
Architecture: x86_64
CPUs: 1
Total Memory: 1.776GiB
Name: manger
ID: baadf173-c534-4bde-9165-a227e8772f24
Docker Root Dir: /var/lib/docker
Debug Mode: false
Experimental: false
Insecure Registries:
127.0.0.0/8
Live Restore Enabled: false
[root@manger ~]# docker node ls
ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS ENGINE VERSION
b5xsdqqky3kzuav4x9i3ks1y3 * manger Ready Active Leader 24.0.4
s080ygbxrkhz2gzc4ubl73x1j node1 Ready Active 24.0.4
kq1xwrkvhukqjtgpa17jw935t node2 Ready Active 24.0.4swarm集群中node的availability状态可以为 active或者drain
active状态下，node可以接受来自manager节点的任务分派；
drain状态下，node节点会结束task，且不再接受来自manager节点的任务分派。下线节点
docker node update --availability drain node1
第四步：在swarm中部署nginx服务
1.创建overlay网络类型
[root@manger ~]# docker network create -d overlay nginx_net
u89gicrtx64t26doogi213vb2
[root@manger ~]# docker network ls
NETWORK ID NAME DRIVER SCOPE
0f9713843296 bridge bridge local
0ac26c162b96 docker_gwbridge bridge local
c1e5931ccec6 host host local
7h617gwnxo9x ingress overlay swarm
u89gicrtx64t nginx_net overlay swarm
23706824b4f2 none null local
2.部署服务
[root@manger ~]# docker service create --replicas 1 --network nginx_net --name nginx-1 -p 8080:80 nginx
sql7arzw1jk9rcpr25mrl2a9d
overall progress: 1 out of 1 tasks
1/1: running [==================================================>]
verify: Service converged
在manager节点上使用上面这个覆盖网络创建nginx服务：
其中，--replicas 参数指定服务由几个实例组成。
注意：不需要提前在节点上下载nginx镜像，这个命令执行后会自动下载这个容器镜像。
[root@manger ~]# docker service ls
ID NAME MODE REPLICAS IMAGE PORTS
sql7arzw1jk9 nginx-1 replicated 1/1 nginx:latest *:8080->80/tcp
3.查看swarm中服务的详细信息
[root@manger ~]# docker service inspect --pretty nginx-1
ID: sql7arzw1jk9rcpr25mrl2a9d
Name: nginx-1
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: nginx:latest@sha256:08bc36ad52474e528cc1ea3426b5e3f4bad8a130318e3140d6cfe29c8892c7ef
Init: false
Resources:
Networks: nginx_net
Endpoint Mode: vip
Ports:
PublishedPort = 8080
Protocol = tcp
TargetPort = 80
PublishMode = ingress
--pretty 是格式化输出
4.查看服务调度到那个节点
[root@manger ~]# docker service ps nginx-1
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
fbuuzgg30vhf nginx-1.1 nginx:latest manger Running Running 6 minutes ago
[root@manger ~]# docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
d8fcb7f18b00 nginx:latest "/docker-entrypoint.…" 8 minutes ago Up 8 minutes 80/tcp nginx-1.1.fbuuzgg30vhf4l6zu7ndtbp6e第五步：在Swarm中动态扩展服务
将nginx-1容器动态扩展到3个
[root@manger ~]# docker service scale nginx-1=3
nginx-1 scaled to 3
overall progress: 3 out of 3 tasks
1/3: running [==================================================>]
2/3: running [==================================================>]
3/3: running [==================================================>]
verify: Service converged
[root@manger ~]# docker service ps nginx-1
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
fbuuzgg30vhf nginx-1.1 nginx:latest manger Running Running 18 minutes ago
d7nhfm0865r4 nginx-1.2 nginx:latest node1 Running Running 5 minutes ago
zm9zh239vrz4 nginx-1.3 nginx:latest node2 Running Running 6 minutes ago
将nginx-1容器动态缩小到1个
[root@manger ~]# docker service scale nginx-1=1
nginx-1 scaled to 1
overall progress: 1 out of 1 tasks
1/1: running [==================================================>]
verify: Service converged
[root@manger ~]# docker service ls
ID NAME MODE REPLICAS IMAGE PORTS
sql7arzw1jk9 nginx-1 replicated 1/1 nginx:latest *:8080->80/tcp
[root@manger ~]# docker service ps nginx-1
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
fbuuzgg30vhf nginx-1.1 nginx:latest manger Running Running 21 minutes ago
[root@manger ~]# docker service update --replicas 3 nginx-1
nginx-1
overall progress: 3 out of 3 tasks
1/3: running [==================================================>]
2/3: running [==================================================>]
3/3: running [==================================================>]
verify: Service converged
[root@manger ~]# docker service ls
ID NAME MODE REPLICAS IMAGE PORTS
sql7arzw1jk9 nginx-1 replicated 3/3 nginx:latest *:8080->80/tcp
[root@manger ~]# docker service ps nginx-1
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
fbuuzgg30vhf nginx-1.1 nginx:latest manger Running Running 23 minutes ago
94k1s7oh5ghg nginx-1.2 nginx:latest node1 Running Running 20 seconds ago
jqx9v4y78hzi nginx-1.3 nginx:latest node2 Running Running 20 seconds ago
docker service update 也可用于直接升级镜像
docker service update --image nginx:new nginx-1
删除nginx-1服务
[root@manger ~]# docker service rm nginx-1
nginx-1
[root@manger ~]# docker service ls
ID NAME MODE REPLICAS IMAGE PORTS注意：如果一个节点宕机了（即该节点就会从swarm集群中被踢出），则Docker会将在该节点运行的容器，调度到其他节点，以满足指定数量的副本保持运行状态。
第六步：Swarm中使用Volume
1.创建卷
[root@manger ~]# docker volume create test-vol
test-vol
[root@manger ~]# docker volume ls
DRIVER VOLUME NAME
local test-vol
2.查看卷的详细信息
[root@manger ~]# docker volume inspect test-vol
[
{
"CreatedAt": "2023-07-11T01:53:04+08:00",
"Driver": "local",
"Labels": null,
"Mountpoint": "/var/lib/docker/volumes/test-vol/_data",
"Name": "test-vol",
"Options": null,
"Scope": "local"
}
]
创建新的服务并挂载test-vol
[root@manger ~]# docker service create --replicas 3 --mount type=volume,src=test-vol,dst=/data --name test-nginx nginx
50fdr2dygc0d6xqnzd9tdtnoz
overall progress: 3 out of 3 tasks
1/3: running [==================================================>]
2/3: running [==================================================>]
3/3: running [==================================================>]
verify: Service converged
[root@manger ~]# docker service ls
ID NAME MODE REPLICAS IMAGE PORTS
50fdr2dygc0d test-nginx replicated 3/3 nginx:latest
[root@manger ~]# docker service ps test-nginx
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
g7sfnacn7rd5 test-nginx.1 nginx:latest node1 Running Running 24 seconds ago
04n0m74ir7lr test-nginx.2 nginx:latest node2 Running Running 24 seconds ago
k5fm278i2war test-nginx.3 nginx:latest manger Running Running 24 seconds ago
进入容器创建test.txt
[root@manger ~]# docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
a61dcb356e84 nginx:latest "/docker-entrypoint.…" About a minute ago Up About a minute 80/tcp test-nginx.3.k5fm278i2war26y2itqg33me5
[root@manger ~]# docker exec -it a61dcb356e84 bash
root@a61dcb356e84:/# cd /data
root@a61dcb356e84:/data# ls
root@a61dcb356e84:/data# echo "welcome to changsha" > test.txt
root@a61dcb356e84:/data# ls
test.txt
root@a61dcb356e84:/data# exit
exit
[root@manger ~]# cd /var/lib/docker/volumes/test-vol/_data
[root@manger _data]# ls
test.txt
[root@manger _data]# cat test.txt
welcome to changsha
还可以将node节点机上的volume数据目录做成软链接
[root@manager _data]# ln -s /var/lib/docker/volumes/testvolume/_data /data
[root@manager _data]# cd /data
[root@manager data]# ls
test.txt
[root@manager data]# echo "123" > a.txt
[root@manager data]# ll
总用量 8
-rw-r--r-- 1 root root 4 7月 21 11:04 a.txt
-rw-r--r-- 1 root root 18 7月 21 11:00 test.txt
另一种种挂载方式
命令格式：
docker service create --mount type=bind,target=/container_data/,source=/host_data/
其中，参数target表示容器里面的路径，source表示本地硬盘路径
docker service create --replicas 1 --mount type=bind,target=/usr/share/nginx/html/,source=/opt/web/ --network nginx_net --name web_nginx -p 8880:80 nginx第七步：多服务Swarm集群部署
通过docker-compose.yml的文件，结合compose和swarm进行多服务的编排。
1.编写docker-compose.yml文件
[root@manager ~]# mkdir testswarm
[root@manager ~]# cd testswarm/
[root@manager testswarm]# cat docker-compose.yml
version: "3"
services:
nginx:
image: nginx
ports:
- 8888:80
deploy:
mode: replicated
replocas: 3
visualizer:
image: dockersamples/visualizer
ports:
- "8080:8080"
volumes:
- "/var/run/docker.sock:/var/run/docker.sock"
deploy:
replicas: 1
placement:
constraints: [node.role == manager]
portainer:
image: portainer/portainer
ports:
- "9000:9000"
volumes:
- "/var/run/docker.sock:/var/run/docker.sock"
deploy:
replicas: 1
placement:
constraints: [node.role == manager]
2.通过这个yml文件部署服务
[root@manager testswarm]# docker stack deploy -c docker-compose.yml deploy_deamon
Creating network deploy_deamon_default
Creating service deploy_deamon_portainer
Creating service deploy_deamon_nginx
Creating service deploy_deamon_visualizer
3.查看服务
[root@manager testswarm]# docker service ls
ID NAME MODE REPLICAS IMAGE PORTS
xj2f1t5ax3nm deploy_deamon_nginx replicated 3/3 nginx:latest *:8888->80/tcp
ky9qpldr5abb deploy_deamon_portainer replicated 1/1 portainer/portainer:latest *:9000->9000/tcp
r47ff177x1ir deploy_deamon_visualizer replicated 1/1 dockersamples/visualizer:latest *:8080->8080/tcp
[root@manager43 testswarm]# docker service ps deploy_deamon_nginx
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
z3v4uc1ujsnq deploy_deamon_nginx.1 nginx:latest node1 Running Running about a minute ago
jhg3ups0cko5 deploy_deamon_nginx.2 nginx:latest manager Running Running about a minute ago
3e6guv791x21 deploy_deamon_nginx.3 nginx:latest node2 Running Running about a minute ago
[root@manager43 testswarm]# docker service ps deploy_deamon_portainer
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
whyuvy82cvvw deploy_deamon_portainer.1 portainer/portainer:latest manager Running Running about a minute ago
[root@manager43 testswarm]# docker service ps deploy_deamon_visualizer
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
wge5w1eqykg3 deploy_deamon_visualizer.1 dockersamples/visualizer:latest manager Running Starting 7 seconds ago本文章为转载内容，我们尊重原作者对文章享有的著作权。如有内容错误或侵权问题，欢迎原作者联系我们进行内容更正或删除文章。
