DEVOPS技术实践_15：使用Docker作为Jenkins的slave

前面实验了使用docker搭建一个jenkins，下面实验使用docker作为jenkins的slave节点

1. 环境准备

一个运行Docker的主机或者群集
Jenkins应该能访问互联网，方便安装插件。
Jenkins服务器能够和GitHub通信。
Jenkinss对Java所需要的Git,和Maven配置应该配置好。
一个Jenkins master.

2. 在Docker主机上开启远端的访问API

此处针对Docker 18.03

/etc/docker/daemon.json会被docker.service的配置文件覆盖，直接添加daemon.json不起作用。可以有如下几种设置：

直接编辑配置文件：Centos中docker daemon配置文件在/lib/systemd/system/docker.service，找到以下字段，在后面添加如下，注意，此处不能用”fd：//”,否则报错

[Unit]
Description=Docker Application Container Engine
Documentation=https://docs.docker.com
BindsTo=containerd.service
After=network-online.target firewalld.service containerd.service
Wants=network-online.target
Requires=docker.socket

[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 -H fd:// --containerd=/run/containerd/containerd.sock
ExecStart=/usr/bin/dockerd -H unix:///var/run/docker.sock -H tcp://0.0.0.0:2375    #添加
ExecReload=/bin/kill -s HUP $MAINPID
TimeoutSec=0
RestartSec=2
Restart=always

# Note that StartLimit* options were moved from "Service" to "Unit" in systemd 229.
# Both the old, and new location are accepted by systemd 229 and up, so using the old location
# to make them work for either version of systemd.
StartLimitBurst=3

# Note that StartLimitInterval was renamed to StartLimitIntervalSec in systemd 230.
# Both the old, and new name are accepted by systemd 230 and up, so using the old name to make
# this option work for either version of systemd.
StartLimitInterval=60s

# Having non-zero Limit*s causes performance problems due to accounting overhead
# in the kernel. We recommend using cgroups to do container-local accounting.
LimitNOFILE=infinity
LimitNPROC=infinity
LimitCORE=infinity

# Comment TasksMax if your systemd version does not support it.
# Only systemd 226 and above support this option.
TasksMax=infinity

# set delegate yes so that systemd does not reset the cgroups of docker containers
Delegate=yes

执行

[root@node6 ~]# systemctl daemon-reload

[root@node6 ~]# systemctl restart docker.service

安装Docker插件

点击【管理Jenkins】–【管理插件】–【可选插件】然后安装此插件

3. 配置Docker插件

点击系统管理----->系统设置

添加配置

然后点击保存

4. 创建Docker镜像

需要创建一个Docker的镜像在Docker主机上，方便我们在创建Jenkins slaves时使用。

查看Docker的镜像

[root@node6 ~]# docker images

REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
jenkins/jenkins     lts                 fac78e370c0b        6 days ago          568MB

拉取ubuntu的镜像

[root@node6 ~]# docker pull centos

Using default tag: latest
latest: Pulling from library/centos
729ec3a6ada3: Pull complete 
Digest: sha256:f94c1d992c193b3dc09e297ffd54d8a4f1dc946c37cbeceb26d35ce1647f88d9
Status: Downloaded newer image for centos:latest
docker.io/library/centos:latest

执行下面的命令运行Docker容器并在容器中执行命令。

[root@node6 ~]# docker run -i -t centos /bin/bash

[root@940907eec8ef /]#

5. 安装所需的应用

添加用户

[root@940907eec8ef /]# useradd jenkins
[root@940907eec8ef /]# yum -y install passwd
[root@940907eec8ef /]# echo 'p@ssw0rd'|passwd --stdin jenkins

[root@940907eec8ef /]# yum update

[root@940907eec8ef /]# yum -y install epel-release

[root@940907eec8ef /]# yum -y install git

[root@940907eec8ef /]# yum -y install java-11-openjdk.x86_64

[root@940907eec8ef /]# yum -y install maven

[root@940907eec8ef /]# exit

[root@node6 ~]# docker ps -a

CONTAINER ID        IMAGE                 COMMAND                  CREATED             STATUS                        PORTS               NAMES
940907eec8ef        centos                "/bin/bash"              11 minutes ago      Exited (0) 6 seconds ago                          naughty_shockley
2c3bfd6ee8a2        ubuntu                "/bin/bash"              12 minutes ago      Exited (1) 11 minutes ago                         nice_mccarthy
8158ddd397d6        ubuntu                "/bin/bash"              31 minutes ago      Exited (100) 13 minutes ago                       determined_sanderson
b119e7f28b50        jenkins/jenkins:lts   "/sbin/tini -- /usr/…"   2 hours ago         Exited (143) 59 minutes ago                       jenkins_prod

6. 保存镜像

[root@node6 ~]# docker commit 940907eec8ef maven-build-slave-0.2

sha256:248e3759ed26b796cc3a2e7bd00c2b2be4b30f4f294c7f14bcbbc96aa3b9f012

[root@node6 ~]# docker images

REPOSITORY              TAG                 IMAGE ID            CREATED             SIZE
maven-build-slave-0.2   latest              248e3759ed26        53 seconds ago      943MB
ubuntu                  latest              775349758637        3 days ago          64.2MB
jenkins/jenkins         lts                 fac78e370c0b        6 days ago          568MB
centos                  latest              0f3e07c0138f        4 weeks ago         220MB