如何构建 systemd 可以直接作为服务执行的 Spring Boot jarfile？

如何构建一个 Spring Boot jarfilesystemd https://freedesktop.org/wiki/Software/systemd/可以直接作为服务执行吗？

按照中的示例作为 systemd 服务安装 http://docs.spring.io/spring-boot/docs/1.4.2.RELEASE/reference/htmlsingle/#deployment-systemd-service，我创建了以下 systemd 服务直接执行 Spring Boot jarfile:

[Unit]
Description=CRS Self-certification Service
Documentation=
Requires=postgresql.service
After=postgresql.service

[Service]
Environment=LOADER_PATH='lib/,config/,/etc/opes/crs/selfcertification'
ExecStart=/opt/opes/crs/selfcertification/crs-selfcertification-1.0.0-SNAPSHOT.jar
Restart=always
RestartSec=10
User=crs

[Install]
WantedBy=multi-user.target

然而，当启动此服务时，systemd 抱怨 jarfile 不可执行：

Nov 29 10:57:59 ubuntu systemd[24109]: selfcertification.service: Failed at step EXEC spawning /opt/opes/crs/selfcertification/crs-selfcertification-1.0.0-SNAPSHOT.jar: Exec format error
Nov 29 10:57:59 ubuntu systemd[1]: selfcertification.service: Main process exited, code=exited, status=203/EXEC
Nov 29 10:57:59 ubuntu systemd[1]: selfcertification.service: Unit entered failed state.
Nov 29 10:57:59 ubuntu systemd[1]: selfcertification.service: Failed with result 'exit-code'.

jar文件的权限是755（所有人可执行）：

administrator@ubuntu:~$ ls -la /opt/opes/crs/selfcertification/crs-selfcertification-1.0.0-SNAPSHOT.jar
-rwxr-xr-x 1 crs selfcertification 35978778 Nov 22 17:16 /opt/opes/crs/selfcertification/crs-selfcertification-1.0.0-SNAPSHOT.jar

为了为 systemd 服务构建可执行 jar 文件，我必须对以下 Gradle 构建脚本进行哪些更改？

buildscript {
    ext {
        springBootVersion = '1.4.2.RELEASE'
    }
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath("org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}")
    }
}

apply plugin: 'java'
apply plugin: 'eclipse'
apply plugin: 'org.springframework.boot'

jar {
    baseName = 'crs-selfcertification'
    version = '1.0.0-SNAPSHOT'
}

sourceCompatibility = 1.8
targetCompatibility = 1.8

repositories {
    mavenCentral()
}

springBoot {
    mainClass = "com.opessoftware.crs.selfcertification.Application"
    layout = "ZIP"
}

dependencies {
    compile("org.springframework.boot:spring-boot-starter-web")
    compile("org.springframework.boot:spring-boot-starter-thymeleaf")
    compile("org.springframework.boot:spring-boot-starter-data-jpa")
    compile("org.springframework.boot:spring-boot-starter-mail")
    testCompile("org.springframework.boot:spring-boot-starter-test")
    compile group: 'org.postgresql', name: 'postgresql', version: '9.4.1208.jre7'
    compile group: 'org.apache.commons', name: 'commons-dbcp2', version: '2.1.1'
    compile group: 'junit', name: 'junit', version: '4.12'

}

请注意，如果不是尝试直接运行 jarfile，而是使用 systemd，则该服务会成功运行使用 Java 虚拟机 (JVM) 从 shell 脚本启动它:

[Unit]
Description=CRS Self-certification Service
Documentation=
Requires=postgresql.service
After=postgresql.service

[Service]
Environment=LOADER_PATH='lib/,config/,/etc/opes/crs/selfcertification'
#ExecStart=/opt/opes/crs/selfcertification/crs-selfcertification-1.0.0-SNAPSHOT.jar
ExecStart=/opt/opes/crs/selfcertification/startCrsSelfCertification
Restart=always
RestartSec=10
User=crs

[Install]
WantedBy=multi-user.target

外壳脚本/opt/opes/crs/selfcertification/startCrsSelfCertification使用 JVM 调用 jarfile：

#!/bin/sh

java -Dloader.path='lib/,config/,/etc/opes/crs/selfcertification' -jar /opt/opes/crs/selfcertification/crs-selfcertification-1.0.0-SNAPSHOT.jar

Spring Boot jarfile 中可能缺少什么，导致 systemd 无法直接执行 jarfile？

您应该指示 Spring Boot 将您的项目重新打包到完全可执行 form:

springBoot {
    executable = true
}

并且此功能仅适用于 Spring Boot 1.4.0+。

参考http://docs.spring.io/spring-boot/docs/current/reference/html/build-tool-plugins-gradle-plugin.html#build-tool-plugins-gradle-repackage-configuration http://docs.spring.io/spring-boot/docs/current/reference/html/build-tool-plugins-gradle-plugin.html#build-tool-plugins-gradle-repackage-configuration了解更多信息。

从 Spring Boot 2.X+, use:

  bootJar {
      launchScript()
  }

Source: 可执行的 Spring Boot 2 jar https://stackoverflow.com/questions/47774075/executable-spring-boot-2-jar