Docker swarm

Swarm 是 Docker 公司在 2014 年 12 月初發布的一套較為簡單的工具,用來管理 Docker 叢集,它將一群 Docker 宿主機變成一個單一的,虛擬的主機。Swarm 使用標準的 Docker API介面作為其前端訪問入口,換言之,各種形式的 Docker Client(docker client in go, docker_py,docker 等)均可以直接與 Swarm 通訊。Swarm 幾乎全部用 Go 語言來完成開發。
Swarm deamon 只是一個排程器(Scheduler)加路由器(router),Swarm 自己不執行容器,它只是接受 docker 客戶端傳送過來的請求,排程適合的節點來執行容器,這意味著,即使Swarm 由於某些原因掛掉了,叢集中的節點也會照常執行,當 Swarm 重新恢復執行之後,它會收集重建叢集資訊

Swarm 的結構圖

實驗環境

系統：rhel7
server1 172.25.41.11
server2 172.25.41.12
server3 172.25.41.13
物理機 172.25.41.250

一·搭建叢集

三臺主機都需要安裝

[[email protected] ~]# ls
docker-engine-17.03.1.ce-1.el7.centos.x86_64.rpm
docker-engine-selinux-17.03
 
.1.ce-1.el7.centos.noarch.rpm
[[email protected] ~]# yum install -y *
[[email protected] ~]# systemctl start docker
[email protected] ~]# yum install -y bash-*    #下載後需要退出再次登陸
[[email protected] images]# ssh [email protected]

[[email protected] ~]# docker swarm init 
Swarm initialized: current node (297
 
d6raqk1k6wv9b9totipqw6) is now a manager.

To add a worker to this swarm, run the following command:

    docker swarm join \
    --token SWMTKN-1-2ygj71qpcyda7k802zu0adgk6ly8z3e80jyd0bcxg3g9ajhnl9-bh2zozew8cg76t0i6jscn9dgb \
    172.25.41.11:2377

To add a manager to this swarm, run 'docker swarm join-token manager' and follow the instructions.

[root@server2 ~]# docker swarm join \
> --token SWMTKN-1-2ygj71qpcyda7k802zu0adgk6ly8z3e80jyd0bcxg3g9ajhnl9-bh2zozew8cg76t0i6jscn9dgb \
> 172.25.41.11:2377

[root@server3 ~]# docker swarm join \
> --token SWMTKN-1-2ygj71qpcyda7k802zu0adgk6ly8z3e80jyd0bcxg3g9ajhnl9-bh2zozew8cg76t0i6jscn9dgb \
> 172.25.41.11:2377

[root@server1 ~]# docker node ls

三臺主機都需要新增解析

[root@server1 ~]# vim /etc/hosts
172.25.41.250   westos.org

[root@foundation41 westos.org]# cd /tmp/docker/
[root@foundation41 docker]# pwd
/tmp/docker
[root@foundation41 docker]# docker run -d --restart=always --name registry -v `pwd`/certs:/certs -e REGISTRY_HTTP_ADDR=0.0.0.0:443 -e REGISTRY_HTTP_TLS_CERTIFICATE=/certs/domain.crt  -e REGISTRY_HTTP_TLS_KEY=/certs/domain.key -p 443:443  registry:2
[root@foundation41 docker]# docker ps -a
[root@foundation41 docker]# cd /etc/docker/
[root@foundation41 docker]# scp -r certs.d/  [email protected]:/etc/docker/
[root@foundation41 docker]# scp -r certs.d/ [email protected]:/etc/docker/
[root@foundation41 docker]# scp -r certs.d/ [email protected]:/etc/docker/
[root@foundation41 docker]# docker push westos.org/nginx

[root@server1 ~]# docker pull westos.org/nginx
[root@server1 ~]# docker service create --name nginx --publish 80:80 --replicas 3 westos.org/nginx
#在manager節點部署nginx服務，服務數量為3個，公開指定埠是8080對映容器80,使用nginx映象
[root@server1 ~]# docker service ls
[root@server1 westos.org]# docker service ps nginx 

[root@server1 westos.org]# docker service scale nginx=6
[root@server1 westos.org]# docker service ps nginx
# 實現負載均衡

網頁訪問會發現實現負載均衡

【物理機】

[root@foundation41 docker]# docker load -i visualizer.tar 
[root@foundation41 docker]# docker images
[root@foundation41 docker]# docker tag dockersamples/visualizer westos.org/visualizer
[root@foundation41 docker]# docker push westos.org/visualizer

【server1】

root@server1 westos.org]# docker service create  --name=viz  --publish=8080:8080/tcp  --constraint=node.role==manager  --mount=type=bind,src=/var/run/docker.sock,dst=/var/run/docker.sock  westos.org/visualizer
[root@server1 westos.org]# docker service ls

網頁訪問：172.25.41.11:8080

[root@server1 ~]# docker service scale nginx=3
[root@server1 ~]# docker service ps nginx       
[root@server1 ~]# docker ps       
[root@server1 ~]# echo server1 > index.html
[root@server1 ~]# docker container cp index.html nginx.5.alzrk6pwrp5cwkkhwxaeon92c:/usr/share/nginx/html

【server2】

[root@server2 ~]# docker ps
[root@server2 ~]# echo server2 > index.html
[root@server2 ~]# docker container cp index.html nginx.4.fbvrxu0hq4392ghog1fdwjw4t:/usr/share/nginx/html

【server3】

[root@server3 ~]# echo server3 > index.html
[root@server3 ~]# docker ps
[root@server3 ~]# docker container cp index.html nginx.2.85yy62a6253peqjx2vyobnuzc:/usr/share/nginx/html

在物理機測試，是否實現負載均衡

[[email protected] docker]# for i in {1..10}; do curl 172.25.41.11;done

滾動更新

物理機
root@foundation41 docker]# docker tag rhel7:v1 westos.org/rhel7:v1
[root@foundation41 docker]# docker push westos.org/rhel7:v1 
server1
[root@server1 ~]# docker service scale nginx=30
[root@server1 ~]# docker service update --image westos.org/rhel7:v1 --update-parallelism 3 --update-delay 10s nginx

[root@server1 ~]# docker service ps nginx