Docker swarm 应用：

镜像准备：

参照Docker学习笔记13，创建centos-nginx:v1的镜像：

[root@swarm-1 nginxtest]# docker build -t centos-nginx:v1 .
[+] Building 211.5s (12/13)
[+] Building 211.7s (12/13)
[+] Building 211.8s (13/14)
[+] Building 212.0s (13/14)
[+] Building 212.1s (13/14)
[+] Building 212.3s (13/14)
[+] Building 212.5s (13/14)
[+] Building 212.6s (13/14)
[+] Building 212.8s (13/14)
[+] Building 212.9s (13/14)
[+] Building 213.1s (13/14)
[+] Building 213.2s (14/14) FINISHED
 => [internal] load build definition from Dockerfile                                                           0.0s
 => => transferring dockerfile: 545B                                                                           0.0s
 => [internal] load .dockerignore                                                                              0.0s
 => => transferring context: 2B                                                                                0.0s
 => [internal] load metadata for docker.io/library/centos:latest                                              11.5s
 => [1/9] FROM docker.io/library/centos:latest@sha256:a27fd8080b517143cbbbab9dfb7c8571c40d67d534bbdee55bd6c4  27.3s
 => => resolve docker.io/library/centos:latest@sha256:a27fd8080b517143cbbbab9dfb7c8571c40d67d534bbdee55bd6c47  0.0s
 => => sha256:a27fd8080b517143cbbbab9dfb7c8571c40d67d534bbdee55bd6c473f432b177 762B / 762B                     0.0s
 => => sha256:a1801b843b1bfaf77c501e7a6d3f709401a1e0c83863037fa3aab063a7fdb9dc 529B / 529B                     0.0s
 => => sha256:5d0da3dc976460b72c77d94c8a1ad043720b0416bfc16c52c45d4847e53fadb6 2.14kB / 2.14kB                 0.0s
 => => sha256:a1d0c75327776413fa0db9ed3adcdbadedc95a662eb1d360dad82bb913f8a1d1 83.52MB / 83.52MB              14.7s  => => extracting sha256:a1d0c75327776413fa0db9ed3adcdbadedc95a662eb1d360dad82bb913f8a1d1                     12.3s  => [internal] load build context                                                                              0.0s  => => transferring context: 58B                                                                               0.0s  => [2/9] RUN cd /etc/yum.repos.d                                                                              1.3s  => [3/9] RUN sed -i 's/mirrorlist/#mirrorlist/g' /etc/yum.repos.d/CentOS-*                                    0.6s  => [4/9] RUN sed -i 's|#baseurl=http://mirror.centos.org|baseurl=http://vault.centos.org|g' /etc/yum.repos.d  0.4s  => [5/9] RUN yum makecache                                                                                   77.5s  => [6/9] RUN yum install -y epel-release                                                                     14.0s  => [7/9] RUN yum install -y nginx                                                                            78.7s  => [8/9] ADD index.html /usr/share/nginx/html/                                                                0.0s  => [9/9] RUN echo "daemon off;" >> /etc/nginx/nginx.conf # 取消nginx为daemon身份运行                                 0.3sporting to image                                                                                         1.3s
 => exporting to image                                                                                         1.4s
 => => exporting layers                                                                                        1.4s
 => => writing image sha256:a361056cbdebc98deb4f28b3a5f1b0a1fcff1265b6d6d6eacebc41ba898e0a8d                   0.0s
 => => naming to docker.io/library/centos-nginx:v1    

给这个镜像打标签：

[root@swarm-1 nginxtest]# docker tag centos-nginx:v1 192.168.17.10/library/centos-nginx:v1
[root@swarm-1 nginxtest]# docker images
REPOSITORY                           TAG       IMAGE ID       CREATED         SIZE
192.168.17.10/library/centos-nginx   v1        a361056cbdeb   7 minutes ago   401MB
centos-nginx                         v1        a361056cbdeb   7 minutes ago   401MB

在执行docker login的时候遇到一个问题：

Error response from daemon: Get https://.. 443: connect: connection refused

网上说这个在/etc/docker/daemon.json增加配置即可，也可以在/usr/lib/systemd/system/docker.service文件修改如下信息也开始可以的。

但是两者不能同时配置。

[Service]
Type=notify
# the default is not to use systemd for cgroups because the delegate issues still
# exists and systemd currently does not support the cgroup feature set required
# for containers run by docker
ExecStart=/usr/bin/dockerd --insecure-registry=192.168.17.10
ExecReload=/bin/kill -s HUP $MAINPID
TimeoutStartSec=0
RestartSec=2
Restart=always

登录的时候我使用：docker login http://swarm-1命令出现登录错误。

但是我直接使用IP地址则登录成功：老师说也尽量使用IP地址。

[root@swarm-1 nginxtest]# docker login 192.168.17.10
Authenticating with existing credentials...
WARNING! Your password will be stored unencrypted in /root/.docker/config.json.
Configure a credential helper to remove this warning. See
https://docs.docker.com/engine/reference/commandline/login/#credentials-store

Login Succeeded
[root@swarm-1 nginxtest]#

上传镜像：

[root@swarm-1 nginxtest]# docker push 192.168.17.10/library/centos-nginx:v1
The push refers to repository [192.168.17.10/library/centos-nginx]
c31095dbe72e: Pushed
15eb46368797: Pushed
f0a8920e6d2e: Pushed
142e7025bba6: Pushed
beaedf47df3d: Pushed
5f8cd1ed84b0: Pushed
fc4701f98edc: Pushed
5f70bf18a086: Pushed
74ddd0ec08fa: Pushed
v1: digest: sha256:c2929f9150abe3c252d413391957fb60706862fe5576535ce30536b4eda72748 size: 2201
[root@swarm-1 nginxtest]#

 检查centos-nginx镜像上传成功：

 

这个是上传的v1版本。

然后现在我们再编辑index.html文件，v1字符改成v2。

然后再次进行打包操作：

[root@swarm-1 nginxtest]# docker build -t 192.168.17.10/library/centos-nginx:v2 .
[+] Building 20.7s (12/13)
[+] Building 20.8s (13/13)
[+] Building 20.8s (14/14) FINISHED
 => [internal] load build definition from Dockerfile                                                           0.0s
 => => transferring dockerfile: 545B                                                                           0.0s
 => [internal] load .dockerignore                                                                              0.0s
 => => transferring context: 2B                                                                                0.0s
 => [internal] load metadata for docker.io/library/centos:latest                                              20.5s
 => [1/9] FROM docker.io/library/centos:latest@sha256:a27fd8080b517143cbbbab9dfb7c8571c40d67d534bbdee55bd6c47  0.0s
 => [internal] load build context                                                                              0.0s
 => => transferring context: 58B                                                                               0.0s
 => CACHED [2/9] RUN cd /etc/yum.repos.d                                                                       0.0s
 => CACHED [3/9] RUN sed -i 's/mirrorlist/#mirrorlist/g' /etc/yum.repos.d/CentOS-*                             0.0s
 => CACHED [4/9] RUN sed -i 's|#baseurl=http://mirror.centos.org|baseurl=http://vault.centos.org|g' /etc/yum.  0.0s
 => CACHED [5/9] RUN yum makecache                                                                             0.0s
 => CACHED [6/9] RUN yum install -y epel-release                                                               0.0s
 => CACHED [7/9] RUN yum install -y nginx                                                                      0.0s  => [8/9] ADD index.html /usr/share/nginx/html/                                                                0.0s  => [9/9] RUN echo "daemon off;" >> /etc/nginx/nginx.conf # 取消nginx为daemon身份运行                                 0.3s
 => exporting to image                                                                                         0.0s
 => => exporting layers                                                                                        0.0s
 => => writing image sha256:2ae4732b884d17c1306ed8e659a7a658e1704510c4164a75358935b39e98c5f1                   0.0s
 => => naming to 192.168.17.10/library/centos-nginx:v2                                                         0.0s
[root@swarm-1 nginxtest]#

 

然后我们再将这个v2版本的镜像进行上传操作，这个时候就不要用再docker login操作了。：

[root@swarm-1 nginxtest]# docker push 192.168.17.10/library/centos-nginx:v2
The push refers to repository [192.168.17.10/library/centos-nginx]
a24e26402f66: Pushed
a4fb63f10d36: Pushed
f0a8920e6d2e: Layer already exists
142e7025bba6: Layer already exists
beaedf47df3d: Layer already exists
5f8cd1ed84b0: Layer already exists
fc4701f98edc: Layer already exists
5f70bf18a086: Layer already exists
74ddd0ec08fa: Layer already exists
v2: digest: sha256:420aaddbb537ea014cafda718148aaea78d219c6bb634f7ef859bf3aa6444b63 size: 2201

 

再次到harbor中检查下上传镜像的情况：

 

发布一个服务：

在管理节点发布服务。

swarm mode中对外暴露的是服务service概念，而不是容器。在swarm mode的设计中，为了保证高可用架构，它准许同时启动多个容器共同支撑一个服务，如果一个容器挂了，它会自动使用另一个容器。

[root@swarm-1 nginxtest]# docker service --help

Usage:  docker service COMMAND

Manage Swarm services

Commands:
  create      Create a new service
  inspect     Display detailed information on one or more services
  logs        Fetch the logs of a service or task
  ls          List services
  ps          List the tasks of one or more services
  rm          Remove one or more services
  rollback    Revert changes to a service's configuration
  scale       Scale one or multiple replicated services
  update      Update a service

Run 'docker service COMMAND --help' for more information on a command.
[root@swarm-1 nginxtest]#

临时举一个例子：

docker service create --replicas 3 --mount "type=bind, source=$PWD, target=/var/lib/registry" --publish 8080:80 --name helloworld centos7.5-base:v1
ping www.baidu.com 

说明：

1）使用centos7.5-base:v1镜像创建一个helloworld服务。

2）--replicas 3 容器复制3份，即共三份。

3）--mount： 数据卷挂载至容器主机，类似于docker run -v选项。

4）--publish：将容器端口映射至容器主机端口，类似于docker run -p选项，可以访问集群中任一个主机均可访问到容器所提供的服务。

5）--name 为服务名称，服务即swarm对外提供的概念。

6）容器镜像最好换成可以实现访问的镜像来创建。

现在：

[root@swarm-1 ~]# docker service create --replicas 2 --publish 8090:80 --name nginxsvc 192.168.17.10/library/centos-nginx:v1

说明：

创建了2个副本，那这个容器可能就在三个node上跑。

[root@swarm-1 ~]# docker service create --replicas 2 --publish 8090:80 --name nginxsvc 192.168.17.10/library/centos-nginx:v1
6idvc01w6gemu04vu2ymj71e6
overall progress: 2 out of 2 tasks
1/2: running   [==================================================>]
2/2: running   [==================================================>]
verify: Service converged

[root@swarm-1 ~]# docker service ls
ID             NAME       MODE         REPLICAS   IMAGE                                   PORTS
6idvc01w6gem   nginxsvc   replicated   2/2        192.168.17.10/library/centos-nginx:v1   *:8090->80/tcp
[root@swarm-1 ~]#
[root@swarm-1 ~]#

[root@swarm-1 ~]# docker service ps nginxsvc
ID             NAME         IMAGE                                   NODE      DESIRED STATE   CURRENT STATE           ERROR     PORTS
ozs9yvsllvie   nginxsvc.1   192.168.17.10/library/centos-nginx:v1   swarm-2   Running         Running 3 minutes ago 
027zzb0h1g8k   nginxsvc.2   192.168.17.10/library/centos-nginx:v1   swarm-1   Running         Running 4 minutes ago 
[root@swarm-1 ~]#

我们怎么访问我们的服务了？

我们从

http://192.168.17.10:8090

http://192.168.17.20:8090

http://192.168.17.30:8090

地址都可以访问到网页。

scale规模扩大和缩小：

扩大：

[root@swarm-1 ~]# docker service scale nginxsvc=3
nginxsvc scaled to 3
overall progress: 3 out of 3 tasks
1/3: running
2/3: running
3/3: running
verify: Service converged
[root@swarm-1 ~]#

[root@swarm-1 ~]# docker service ps nginxsvc
ID             NAME         IMAGE                                   NODE      DESIRED STATE   CURRENT STATE            ERROR     PORTS
ozs9yvsllvie   nginxsvc.1   192.168.17.10/library/centos-nginx:v1   swarm-2   Running         Running 9 minutes ago
027zzb0h1g8k   nginxsvc.2   192.168.17.10/library/centos-nginx:v1   swarm-1   Running         Running 10 minutes ago
kzqdhwob8od9   nginxsvc.3   192.168.17.10/library/centos-nginx:v1   swarm-3   Running         Running 47 seconds ago

 缩小：

[root@swarm-1 ~]# docker service scale nginxsvc=1
nginxsvc scaled to 1
overall progress: 1 out of 1 tasks
1/1: running
verify: Service converged
[root@swarm-1 ~]#
[root@swarm-1 ~]# docker service ps nginxsvc
ID             NAME         IMAGE                                   NODE      DESIRED STATE   CURRENT STATE            ERROR     PORTS
ozs9yvsllvie   nginxsvc.1   192.168.17.10/library/centos-nginx:v1   swarm-2   Running         Running 11 minutes ago

这个时候，我们从三个网址仍然可以访问到服务。

滚动更新版本：

滚动更新可以在用户端无感知的情况下进行软件升级：

[root@swarm-1 ~]# docker service update --image 192.168.17.10/library/centos-nginx:v2 nginxsvc
nginxsvc
overall progress: 1 out of 1 tasks
1/1: running
verify: Service converged

然后再在浏览器中验证页面是否变为v2，发现立即更新了。

速度非常快。

所以，这个命令要熟练。

版本回退：

[root@swarm-1 ~]# docker service update --image 192.168.17.10/library/centos-nginx:v1 nginxsvc
nginxsvc
overall progress: 1 out of 1 tasks
1/1: running
verify: Service converged
[root@swarm-1 ~]#

发现版本回退也还非常快的。

间隔更新方法：

[root@swarm-1 ~]# docker service update --replicas 3 --image 192.168.17.10/library/centos-nginx:v2 --update-parallelism 1 --update-delay 30s  nginxsvc
nginxsvc
overall progress: 3 out of 3 tasks
1/3: running
2/3: running
3/3: running
verify: Service converged
[root@swarm-1 ~]#

说明：

1）--update --parallelism: 每次更新一个。

2）--update-delay: 延迟时间，一个更新好之后，延迟多少秒，然后再更新第二个。

移除服务：

[root@swarm-1 ~]# docker service rm nginxsvc
nginxsvc