创建Linux服务，轻松管理（自启动，恢复）进程-CFANZ编程社区

有这样一个场景，在一台服务器上，我们想要启动一个简单的网络文件服务器，用来提供给内网的用户下载。

这里，我们使用ruby启动一个服务

使用ruby -run -ehttpd /home/webbuild/easy_file_server/ -p8000启动文件服务器
使用ruby -run -ehttpd /home/webbuild/easy_file_server/ -p8000 & 将该进程设置为后台执行
为了防止挂起，我们还需要使用nohup处理。像这样nohup ruby -run -ehttpd /home/webbuild/easy_file_server/ -p8000 &

如上面设置一番，基本上可以工作了。

但是还有一些问题，比如

进程意外停止了，无法自动启动
服务器重启，该进程也不会自动启动

那么我们有没有什么好的办法解决呢，答案是有的。就是下面介绍的使用systemd创建Linux 服务的方式解决。

创建服务Unit文件

创建一个服务文件，比如这里叫做vim /etc/systemd/system/apk_server.service(可以将apk_server替换为你希望的名称)

内容如下

[Unit] Description=APK Server Service StartLimitIntervalSec=0 [Service] Type=simple Restart=always RestartSec=1 User=root ExecStart=/usr/bin/env ruby -run -ehttpd /home/webbuild/easy_file_server/ -p8000 [Install] WantedBy=multi-user.target

[Unit]
Description=APK Server Service
StartLimitIntervalSec=0
[Service]
Type=simple
Restart=always
RestartSec=1
User=root
ExecStart=/usr/bin/env ruby -run -ehttpd /home/webbuild/easy_file_server/  -p8000

[Install]
WantedBy=multi-user.target

重点可能需要替换的有

Description 该服务的描述信息
User 填写真实的用户名称，也可以填写root不修改。
ExecStart 必须替换为你需要执行的命令。

基本搞定了

启动服务

systemctl start apk_server.service

停止服务

systemctl stop apk_server.service

重新启动服务

systemctl restart apk_server.service

设置开启自启动

systemctl enable apk_server.service //执行结果 Created symlink /etc/systemd/system/multi-user.target.wants/apk_server.service → /etc/systemd/system/apk_server.service.

其他字段解释

StartLimitIntervalSec 启动频率限制，设置为0
Restart=always 当进程退出后自动重启
RestartSec 重启延迟时间，单位为毫秒
WantedBy 自动启动相关参数

查看服务状态

systemctl status apk_server.service ● apk_server.service - APK Server Service Loaded: loaded (/etc/systemd/system/apk_server.service; disabled; vendor preset: disabled) Active: active (running) since Fri 2019-12-xx 22:06:40 CST; 9s ago Main PID: 17802 (ruby) Tasks: 2 (limit: 26213) Memory: 15.8M CGroup: /system.slice/apk_server.service └─17802 ruby -run -ehttpd /home/webbuild/easy_file_server/ -p8000 localhost.localdomain systemd[1]: Started APK Server Service. localhost.localdomain env[17802]: [2019-12-xx 22:06:40] INFO WEBrick 1.4.2 localhost.localdomain env[17802]: [2019-12-xx 22:06:40] INFO ruby 2.5.3 (2018-10-18) [x86_64-linux] localhost.localdomain env[17802]: [2019-12-xx 22:06:40] INFO WEBrick::HTTPServer#start: pid=17802 port=8000

systemctl status apk_server.service
● apk_server.service - APK Server Service
   Loaded: loaded (/etc/systemd/system/apk_server.service; disabled; vendor preset: disabled)
   Active: active (running) since Fri 2019-12-xx 22:06:40 CST; 9s ago
 Main PID: 17802 (ruby)
    Tasks: 2 (limit: 26213)
   Memory: 15.8M
   CGroup: /system.slice/apk_server.service
           └─17802 ruby -run -ehttpd /home/webbuild/easy_file_server/ -p8000

localhost.localdomain systemd[1]: Started APK Server Service.
localhost.localdomain env[17802]: [2019-12-xx 22:06:40] INFO  WEBrick 1.4.2
localhost.localdomain env[17802]: [2019-12-xx 22:06:40] INFO  ruby 2.5.3 (2018-10-18) [x86_64-linux]
localhost.localdomain env[17802]: [2019-12-xx 22:06:40] INFO  WEBrick::HTTPServer#start: pid=17802 port=8000

配置更新

当我们修改了之前的service文件后，会得到的提示

Warning: The unit file, source configuration file or drop-ins of apk_server.service changed on disk. Run ‘systemctl daemon-reload’ to reload units.

所以，当我们每次修改后，都需要执行systemctl daemon-reload确保配置生效。

排查错误

查找错误信息

可以使用使用两种方法

第一种是systemctl status，上面介绍的
第二种是journalctl

journalctl

journalctl相对提供的日志会更多一些，使用方法也很简单

journalctl -u coo_code_review.service --no-pager --reverse

对应的日志就能看到了

localhost.localdomain systemd[1]: coo_code_review.service: Failed with result 'exit-code'. localhost.localdomain systemd[1]: coo_code_review.service: Service RestartSec=1s expired, scheduling restart. localhost.localdomain systemd[1]: coo_code_review.service: Scheduled restart job, restart counter is at 52. localhost.localdomain systemd[1]: Stopped Coo Code Review Service. localhost.localdomain systemd[1]: Started Coo Code Review Service.

localhost.localdomain systemd[1]: coo_code_review.service: Failed with result 'exit-code'.
localhost.localdomain systemd[1]: coo_code_review.service: Service RestartSec=1s expired, scheduling restart.
localhost.localdomain systemd[1]: coo_code_review.service: Scheduled restart job, restart counter is at 52.
localhost.localdomain systemd[1]: Stopped Coo Code Review Service.
localhost.localdomain systemd[1]: Started Coo Code Review Service.

code=exited, status=217/USER

apk_server.service - APK Server Service Loaded: loaded (/etc/systemd/system/apk_server.service; disabled; vendor preset: disabled) Active: activating (auto-restart) (Result: exit-code) since Fri 2019-12-20 14:03:12 CST; 409ms ago Process: 17535 ExecStart=/usr/bin/env bash /root/startApkServer.sh (code=exited, status=217/USER) Main PID: 17535 (code=exited, status=217/USER)

apk_server.service - APK Server Service
   Loaded: loaded (/etc/systemd/system/apk_server.service; disabled; vendor preset: disabled)
   Active: activating (auto-restart) (Result: exit-code) since Fri 2019-12-20 14:03:12 CST; 409ms ago
  Process: 17535 ExecStart=/usr/bin/env bash /root/startApkServer.sh (code=exited, status=217/USER)
 Main PID: 17535 (code=exited, status=217/USER)

通常的错误原因是上面配置中的User设置的用户名不对。更新正确即可

设置工作目录

很多是否我们的命令会是这样

进入一个目录
然后执行命令

但是当我们这样设置ExecStart=/usr/bin/env cd your_dir && ruby -run -ehttpd easy_file_server/ -p8000是有问题的。好在可以这样设置工作目录

[Unit] Description=APK Server Service StartLimitIntervalSec=0 [Service] Type=simple Restart=always RestartSec=1 User=root WorkingDirectory=/root/your_dir ExecStart=/usr/bin/env ruby -run -ehttpd /home/webbuild/easy_file_server/ -p8000 [Install] WantedBy=multi-user.target

[Unit]
Description=APK Server Service
StartLimitIntervalSec=0
[Service]
Type=simple
Restart=always
RestartSec=1
User=root
WorkingDirectory=/root/your_dir
ExecStart=/usr/bin/env ruby -run -ehttpd /home/webbuild/easy_file_server/  -p8000

[Install]
WantedBy=multi-user.target

通过增加WorkingDirectory=/root/your_dir可以解决问题。

设置环境变量

[Unit] Description=xxxxx Service StartLimitIntervalSec=0 [Service] Type=simple Restart=always RestartSec=1 User=root Environment="ANDROID_HOME=/opt/android-sdk-linux" WorkingDirectory=/root/automan/xxx ExecStart=/usr/bin/env bash /root/automan/xxx/gradlew run [Install] WantedBy=multi-user.target

[Unit]
Description=xxxxx Service
StartLimitIntervalSec=0
[Service]
Type=simple
Restart=always
RestartSec=1
User=root
Environment="ANDROID_HOME=/opt/android-sdk-linux"
WorkingDirectory=/root/automan/xxx
ExecStart=/usr/bin/env bash /root/automan/xxx/gradlew run

[Install]
WantedBy=multi-user.target

使用上面的代码，我们就增加了ANDROID_HOME=/opt/android-sdk-linux这个环境变量。

如果是多个环境变量，设置多行Environment="ANDROID_HOME=/opt/android-sdk-linux"就行

203/EXEC 错误

localhost.localdomain systemd[1]: Started Coo Code Review Service. localhost.localdomain systemd[1]: coo_code_review.service: Main process exited, code=exited, status=203/EXEC localhost.localdomain systemd[1]: coo_code_review.service: Failed with result 'exit-code'.

localhost.localdomain systemd[1]: Started Coo Code Review Service.
localhost.localdomain systemd[1]: coo_code_review.service: Main process exited, code=exited, status=203/EXEC
localhost.localdomain systemd[1]: coo_code_review.service: Failed with result 'exit-code'.

解决方法,增加/usr/bin/env

ExecStart=/usr/bin/env bash /root/automan/xxxxx/gradlew run