由於 jar 包之外的配置文件的 FileInputStreamException，Java 守護程序一直失敗

我想用標準的 Debian Stretch（核心版本 4.9）將 Java 應用程序實現為在我的 Raspberry Pi 上執行的守護程序/服務。

Java 應用程序啟動但隨後拋出異常，因為它無法讀取位於 jar 之外的重要配置文件。這是設計使然。我想將配置文件保留在 jar 之外。

我通過將配置文件放入 jar 並通過 InputStream 讀取文件來執行它。但要求是配置文件不在 jar 中。通過終端手動啟動 jar 也可以。文件權限應該沒問題，如以 root 身份啟動的工作手冊所示。

我的預感是工作目錄在服務啟動期間變得混亂。另一個預感是通過 FileInputStream 導航文件系統會導致問題。

這是我的服務文件：

[Unit]
Description=collector

[Service]
User=root
CHDIR=/opt/servicedir/

#application.properties:
ExecStart=/usr/bin/java -jar /opt/servicedir/javaapp.jar
SuccessExitStatus=143
TimeoutStopSec=10
Restart=on-failure
RestartSec=5

[Install]
WantedBy=multi-user.target

/opt/servicedir/ 中所有內容的文件權限： sudo chmod -R 770 /opt/servicedir/

來自系統日誌的異常：

Aug 31 14:38:58 raspberrypi systemd[1]: myservice.service: Main process exited, code=exited, status=1/FAILURE
Aug 31 14:38:58 raspberrypi systemd[1]: myservice.service: Unit entered failed state.
Aug 31 14:38:58 raspberrypi systemd[1]: myservice.service: Failed with result 'exit-code'.
Aug 31 14:39:03 raspberrypi systemd[1]: myservice.service: Service hold-off time over, scheduling restart.
Aug 31 14:39:03 raspberrypi systemd[1]: Stopped service
Aug 31 14:39:03 raspberrypi systemd[1]: Started service
Aug 31 14:39:04 raspberrypi java[7982]: Exception in thread "main" java.lang.ExceptionInInitializerError
Aug 31 14:39:04 raspberrypi java[7982]: #011at foo.bar.Application.<clinit>(Application.java:20)
Aug 31 14:39:04 raspberrypi java[7982]: #011at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
Aug 31 14:39:04 raspberrypi java[7982]: #011at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
Aug 31 14:39:04 raspberrypi java[7982]: #011at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
Aug 31 14:39:04 raspberrypi java[7982]: #011at java.lang.reflect.Method.invoke(Method.java:497)
Aug 31 14:39:04 raspberrypi java[7982]: #011at org.springframework.boot.loader.MainMethodRunner.run(MainMethodRunner.java:48)
Aug 31 14:39:04 raspberrypi java[7982]: #011at org.springframework.boot.loader.Launcher.launch(Launcher.java:87)
Aug 31 14:39:04 raspberrypi java[7982]: #011at org.springframework.boot.loader.Launcher.launch(Launcher.java:50)
Aug 31 14:39:04 raspberrypi java[7982]: #011at org.springframework.boot.loader.JarLauncher.main(JarLauncher.java:51)
Aug 31 14:39:04 raspberrypi java[7982]: Caused by: java.lang.RuntimeException: Failed to load credentials.properties.
Aug 31 14:39:04 raspberrypi java[7982]: #011at foo.bar.Config.<clinit>(Config.java:60)
Aug 31 14:39:04 raspberrypi java[7982]: #011... 9 more
Aug 31 14:39:04 raspberrypi java[7982]: Caused by: java.io.FileNotFoundException: ./res/credentials.properties (Datei oder Verzeichnis nicht gefunden)
Aug 31 14:39:04 raspberrypi java[7982]: #011at java.io.FileInputStream.open0(Native Method)
Aug 31 14:39:04 raspberrypi java[7982]: #011at java.io.FileInputStream.open(FileInputStream.java:195)
Aug 31 14:39:04 raspberrypi java[7982]: #011at java.io.FileInputStream.<init>(FileInputStream.java:138)
Aug 31 14:39:04 raspberrypi java[7982]: #011at java.io.FileInputStream.<init>(FileInputStream.java:93)
Aug 31 14:39:04 raspberrypi java[7982]: #011at foo.bar.Application.Config.<clinit>(Config.java:44)
Aug 31 14:39:04 raspberrypi java[7982]: #011... 9 more
Aug 31 14:39:04 raspberrypi systemd[1]: myservice.service: Main process exited, code=exited, status=1/FAILURE
Aug 31 14:39:04 raspberrypi systemd[1]: myservice.service: Unit entered failed state.
Aug 31 14:39:04 raspberrypi systemd[1]: myservice.service: Failed with result 'exit-code'.

這裡來自java程式碼的程式碼行：

   //  this does not work :
   String credentialsFilePath = "./res/credentials.properties"
   try (FileInputStream in = new FileInputStream(credentialsFilePath)) {


   // this line works with the config file inside the jar
   String credentialsInJar = "credentials.properties"
   try (InputStream in = Config.class.getResourceAsStream(credentialsInJar)) {

您尚未在 systemd 單元中設置工作目錄。不過，看起來您打算設置一個。

我懂了：

CHDIR=/opt/servicedir/

但是沒有這樣的配置選項。

要設置服務啟動的工作目錄，請使用WorkingDirectory=. 例如：

WorkingDirectory=/opt/servicedir

引用自：https://serverfault.com/questions/928874