利用C＃编写Linux守护进程实例代码

前言

linux守护进程是linux的后台服务进程，相当于windows服务，对于为linux开发服务程序的朋友来说，linux守护进程相关技术是必不可少的，因为这个技术不仅仅是为了开发守护进程，还可以拓展到多进程，父子进程文件描述符共享，父子进程通讯、控制等方面，是实现linux大型服务的基础技术之一。

如果要在red hat enterprise linux上将.net core进程作为后台进程运行，则可以创建自定义systemd单元。今天我将为.net core编写两个自定义系统单元的例子。一个是运行.net core控制台应用程序的一种类型，另一个是运行asp.net core web应用程序的简单类型。

控制台应用程序

建立一个应用程序

您可以用dotnet run在systemd中使用指定项目目录作为工作目录。但是，我们来构建一个二进制文件并将其用于systemd。用dotnet new 命令创建您的项目后编辑program.cs如下。

using system;
using system.io;
namespace consoleapplication
{
 public class program
 {
  public static void main(string[] args)
  {
   var path = path.gettempfilename();
   file.writealltext(path, "hello temp file!");
   console.writeline($"wrote temp file: {path}");
  }
 }
}

然后用dotnet publish命令发布项目。你会看到bin/<configuration>/<framework>目录下的二进制文件。

$ dotnet publish -c release
publishing consoleapp for .netcoreapp,version=v1.1
project consoleapp (.netcoreapp,version=v1.1) was previously compiled. skipping compilation.
publish: published to /home/tatanaka/documents/git/tanaka-takayoshi/systemdexample/1.1/consoleapp/bin/release/netcoreapp1.1/publish
published 1/1 projects successfully

创建一个自定义的systemd

首先，创建一个运行守护进程和工作目录的用户。

$ sudo useradd -s /sbin/nologin dotnetuser
$ sudo mkdir /var/systemdexample
$ sudo cp /home/tatanaka/documents/git/tanaka-takayoshi/systemdexample/1.1/consoleapp/bin/release/netcoreapp1.1/publish/* /var/systemdexample
$ sudo chown -r dotnetuser:dotnetuser /var/systemdexample

然后在/etc/systemd/system/目录下创建一个自定义的systemd单元文件。文件名应该是<unit-name>.<unit-type>。我创建的目录和文件名为：/etc/systemd/system/netcore-console-example.service。

[unit]
description=example for .net core consoleapp with systemd
defaultdependencies=no
 
[service]
type=oneshot
remainafterexit=no
execstart=/opt/rh/rh-dotnetcore11/root/usr/bin/dotnet consoleapp.dll
workingdirectory=/var/systemdexample
user=dotnetuser
group=dotnetuser
 
 
[install]

您应该在execstart中指定dotnet的完整路径。以上是红帽提供的.net core 1.1的情况。然后你可以用systemctl命令执行守护进程。您可以使用systemctl status命令或journalctl命令查看控制台输出。

$ sudo systemctl start netcore-console-example.service
$ sudo systemctl status netcore-console-example.service
● netcore-console-example.service - example for .net core consoleapp with systemd
 loaded: loaded (/etc/systemd/system/netcore-console-example.service; enabled; vendor preset: disabled)
 active: inactive (dead) since fri 2017-02-24 00:29:16 jst; 13s ago
 process: 18075 execstart=/opt/rh/rh-dotnetcore11/root/usr/bin/dotnet consoleapp.dll (code=exited, status=0/success)
 main pid: 18075 (code=exited, status=0/success)
 
feb 24 00:29:16 localhost.localdomain systemd[1]: starting example for .net core consoleapp with systemd...
feb 24 00:29:16 localhost.localdomain dotnet[18075]: wrote temp file: /tmp/tmph1ok6h.tmp
feb 24 00:29:16 localhost.localdomain systemd[1]: started example for .net core consoleapp with systemd.
 
$ journalctl -u netcore-console-example.service -e
feb 24 00:29:16 localhost.localdomain systemd[1]: starting example for .net core consoleapp with systemd...
feb 24 00:29:16 localhost.localdomain dotnet[18075]: wrote temp file: /tmp/tmph1ok6h.tmp
feb 24 00:29:16 localhost.localdomain systemd[1]: started example for .net core consoleapp with systemd.
$ sudo cat /tmp/tmph1ok6h.tmp
hello temp file!

使用privatetemp

在上述系统单元中，程序在临时文件夹下写入一个文件。你有时想写一个来自其他用户的临时文件是安全的。您可以在[service]section中的指定使用privatetemp。

[service]
type=oneshot
remainafterexit=no
execstart=/opt/rh/rh-dotnetcore11/root/usr/bin/dotnet consoleapp.dll
workingdirectory=/var/systemdexample
user=dotnetuser
group=dotnetuser
privatetemp=true

重新加载单元文件后，程序可以像前一样访问/tmp目录，但这不是实际的/tmp目录。

$ sudo systemctl daemon-reload 
$ sudo systemctl start netcore-console-example.service
$ sudo systemctl status netcore-console-example.service
● netcore-console-example.service - example for .net core consoleapp with systemd
 loaded: loaded (/etc/systemd/system/netcore-console-example.service; enabled; vendor preset: disabled)
 active: inactive (dead) since fri 2017-02-24 00:35:46 jst; 12s ago
 process: 18415 execstart=/opt/rh/rh-dotnetcore11/root/usr/bin/dotnet consoleapp.dll (code=exited, status=0/success)
 main pid: 18415 (code=exited, status=0/success)
 
feb 24 00:35:46 localhost.localdomain systemd[1]: starting example for .net core consoleapp with systemd...
feb 24 00:35:46 localhost.localdomain dotnet[18415]: wrote temp file: /tmp/tmpjlwagc.tmp
feb 24 00:35:46 localhost.localdomain systemd[1]: started example for .net core consoleapp with systemd.
$ ls /tmp/tmpjlwagc.tmp
ls: cannot access /tmp/tmpjlwagc.tmp: no such file or directory

web应用程序

建立一个应用程序

现在我们来构建一个asp.net core web应用程序。今天我使用默认的模板项目。

$ dotnet new -t web
created new c# project in /home/tatanaka/documents/git/tanaka-takayoshi/systemdexample/1.1/webapp.
$ dotnet restore 
** snipped**
log : restore completed in 9721ms.
$ dotnet publish -c release
publishing webapp for .netcoreapp,version=v1.1
** snipped **
publish: published to /home/tatanaka/documents/git/tanaka-takayoshi/systemdexample/1.1/webapp/bin/release/netcoreapp1.1/publish
published 1/1 projects successfully

现在可以用dotnet命令运行。

$ dotnet bin/release/netcoreapp1.1/publish/webapp.dll 
info: microsoft.extensions.dependencyinjection.dataprotectionservices[0]
  user profile is available. using '/home/tatanaka/.aspnet/dataprotection-keys' as key repository; keys will not be encrypted at rest.
hosting environment: production
content root path: /home/tatanaka/documents/git/tanaka-takayoshi/systemdexample/1.1/webapp
now listening on: http://localhost:5000
application started. press ctrl+c to shut down.

创建一个自定义的systemd

为这个web应用程序也指定dotnetuser名称。

$ sudo mkdir /var/systemdexample
$ sudo cp -r bin/release/netcoreapp1.1/publish/* /var/systemdwebexample
$ sudo chown -r dotnetuser:dotnetuser /var/systemdwebexample

然后创建一个自定义的systemd单元文件/etc/systemd/system/netcore-web-example.service。

[unit]
description=example for .net core webapp with systemd
defaultdependencies=no
wants=network.target # network is required
after=network.target
 
[service]
execstart=/opt/rh/rh-dotnetcore11/root/usr/bin/dotnet webapp.dll
workingdirectory=/var/systemdwebexample
restart=always
restartsec=10 # restart service after 10 seconds if dotnet service crashes
syslogidentifier=dotnet-example
user=dotnetuser
group=dotnetuser
privatetmp=true
environment=aspnetcore_environment=production # specify environment variable for environment
environment=aspnetcore_urls=http://*:8080 # specify environement variable for listening port
 
[install]
wantedby = multi-user.target

最后，您可以将asp.net core应用程序作为linux守护程序运行。请注意，此应用程序侦听端口8080代替了asp.net core 默认的 5000，因为我在aspnetcore_urls单元文件中指定了环境变量  。

$ systemctl start netcore-web-example.service
[tatanaka@localhost webapp]$ systemc^c
[tatanaka@localhost webapp]$ sudo systemctl status netcore-web-example.service
[sudo] password for tatanaka: 
● netcore-web-example.service - example for .net core webapp with systemd
 loaded: loaded (/etc/systemd/system/netcore-web-example.service; disabled; vendor preset: disabled)
 active: active (running) since sat 2017-02-25 01:02:12 jst; 11s ago
 main pid: 7041 (dotnet)
 cgroup: /system.slice/netcore-web-example.service
   └─7041 /opt/rh/rh-dotnetcore11/root/usr/bin/dotnet webapp.dll
 
feb 25 01:02:12 localhost.localdomain systemd[1]: started example for .net core webapp with systemd.
feb 25 01:02:12 localhost.localdomain systemd[1]: starting example for .net core webapp with systemd...
feb 25 01:02:12 localhost.localdomain dotnet-example[7041]: info: microsoft.extensions.dependencyinjection.dataprotectionservices[0]
feb 25 01:02:12 localhost.localdomain dotnet-example[7041]: user profile is available. using '/home/dotnetuser/.aspnet/dataprotection-keys' as key repository; keys will not be encrypted at rest.
feb 25 01:02:13 localhost.localdomain dotnet-example[7041]: hosting environment: production
feb 25 01:02:13 localhost.localdomain dotnet-example[7041]: content root path: /var/systemdwebexample
feb 25 01:02:13 localhost.localdomain dotnet-example[7041]: now listening on: http://*:8080
feb 25 01:02:13 localhost.localdomain dotnet-example[7041]: application started. press ctrl+c to shut down.
 
$ journalctl -u netcore-web-example -xf
-- logs begin at mon 2017-02-20 11:58:31 jst. --
feb 25 01:02:36 localhost.localdomain dotnet-example[7041]: info: microsoft.aspnetcore.staticfiles.staticfilemiddleware[2]
feb 25 01:02:36 localhost.localdomain dotnet-example[7041]: sending file. request path: '/images/banner4.svg'. physical path: '/var/systemdwebexample/wwwroot/images/banner4.svg'
feb 25 01:02:36 localhost.localdomain dotnet-example[7041]: info: microsoft.aspnetcore.hosting.internal.webhost[2]
feb 25 01:02:36 localhost.localdomain dotnet-example[7041]: request finished in 0.1973ms 200 image/svg+xml
feb 25 01:02:36 localhost.localdomain dotnet-example[7041]: info: microsoft.aspnetcore.hosting.internal.webhost[1]
feb 25 01:02:36 localhost.localdomain dotnet-example[7041]: request starting http/1.1 get http://localhost:8080/favicon.ico
feb 25 01:02:36 localhost.localdomain dotnet-example[7041]: info: microsoft.aspnetcore.staticfiles.staticfilemiddleware[2]
feb 25 01:02:36 localhost.localdomain dotnet-example[7041]: sending file. request path: '/favicon.ico'. physical path: '/var/systemdwebexample/wwwroot/favicon.ico'
feb 25 01:02:36 localhost.localdomain dotnet-example[7041]: info: microsoft.aspnetcore.hosting.internal.webhost[2]
feb 25 01:02:36 localhost.localdomain dotnet-example[7041]: request finished in 0.5824ms 200 image/x-icon

然而这对于asp.net core的生产使用来说是不够的。你可能需要设置一个反向代理服务器，比如jexus,nginx，防火墙等等。

writing a linux daemon in c#

总结

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