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StandardInput=套接字服务运行失败

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StandardInput=套接字服务运行失败

我有一个简单的套接字/服务对，其中服务依赖于来自套接字的标准输入：

# /etc/systemd/system/simple.socket
[Unit]
Description=Simple socket

[Socket]
ListenStream=11111

# /etc/systemd/system/simple.service
[Unit]
Description=Simple service

[Service]
Type=simple
ExecStart=-cat -
StandardInput=socket
StandardOutput=socket

当我尝试启动时，netcat 127.0.0.1 11111我得到：

- simple.service - "Simple service"
     Loaded: loaded (/etc/systemd/system/simple.service; vendor preset: enabled)
     Active: failed (Result: start-limit-hit) since Tue 2020-05-19 09:42:17 CEST; 11min ago
TriggeredBy: simple.socket
    Process: 400879 ExecStart=/bin/cat - (code=exited, status=1/FAILURE)
   Main PID: 400879 (code=exited, status=1/FAILURE)

- simple.socket - "Simple socket"
     Loaded: loaded (/etc/systemd/system/simple.socket; static; vendor preset: enabled)
     Active: failed (Result: service-start-limit-hit) since Tue 2020-05-19 09:42:17 CEST; 11min ago
   Triggers: simple.service
     Listen: [::]:11111 (Stream)

我的猜测是cat无法启动，因为它正在尝试连接到stdin不可用的连接。如果我替换cat -为sleep infinity服务，则启动正常。我不明白为什么

答案1

Accept=该解决方案与套接字选项有关。

这个版本可以工作：

# /etc/systemd/system/simple.socket
[Unit]
Description=Simple socket

[Socket]
Accept=yes
ListenStream=11111

记下新的文件路径

# /etc/systemd/system/[email protected]
[Unit]
Description=Simple service

[Service]
Type=simple
ExecStart=-cat -
StandardInput=socket
StandardOutput=socket

现在nc 127.0.0.1 11111不返回，让您回显您发送的任何内容。现在还systemctl status simple*给出：

- simple.socket - Simple socket
     Loaded: loaded /etc/systemd/system/simple.socket; static: vendor preset: enabled)
     Active: active (listening) since Tue 2020-05-19 10:04:48 CEST; 48s ago
   Triggers: [email protected]:11111-127.0.0.1:47194.service
     Listen: [::]:11111 (Stream)
   Accepted: 2; Connected: 1;
      Tasks: 0 (limit: 9429)
     Memory: 120.0K
     CGroup: /system.slice/simple.socket

- [email protected]:11111-127.0.0.1:47194.service - "Simple service" (127.0.0.1:47194)
     Loaded: loaded /etc/systemd/system/[email protected]; static: vendor preset: enabled)
     Active: active (running) since Tue 2020-05-19 10:04:48 CEST; 48s ago
TriggeredBy: simple.socket
   Main PID: 403830 (cat)
      Tasks: 1 (limit: 9429)
     Memory: 184.0K
     CGroup: /system.slice/system-simple.slice/[email protected]:11111-127.0.0.1:47194.service
             -403830 /bin/cat -

我认为这是可行的，因为当 时Accept=no，每个连接都尝试连接到同一进程，并且尝试将多个套接字复用到单个标准输入中有点奇怪。每个Accept=yes连接都会产生一个新进程，因此可以很简单地将套接字通过管道传输到每个进程的标准输入中。

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