bitbake - Enable systemd services using yocto

Question

Hi this is my layer tree

├── conf
│?? └── layer.conf
├── COPYING.MIT
├── README
└── recipes-hello
    ├── helloworld
    │?? ├── helloworld-0.1
    │?? │?? ├── helloworld.c
    │?? │?? ├── helloworld.patch
    │?? │?? └── newhelloworld.c
    │?? └── helloworld_0.1.bb
    ├── message
    │?? ├── message-0.1
    │?? │?? └── message.txt
    │?? └── message_0.1.bb
    └── service
        ├── service-0.1
        │?? ├── test_systemd.service
        │?? └── test_systemd.sh
        └── service_0.1.bb

Here test_systemd.service is the service file which have to invoke test_systemd.sh, which I am trying to achieve using service_0.1.bb

    # This recipe performs the following tasks
    # 1) Install .sh file in /home/root/ and .sh script creates a random text file
    # 2) Install the .service file in systemd directory
    # 3) Invoke the .sh script via .service file
    inherit systemd

SUMMARY = "Install and start a systemd service"
SECTION = "examples"
LICENSE = "MIT"
LIC_FILES_CHKSUM = "file://${COMMON_LICENSE_DIR}/MIT;md5=0835ade698e0bcf8506ecda2f7b4f302"

#here we specify the source we want to build
SRC_URI = "file://test_systemd.sh"
SRC_URI += "file://test_systemd.service"
#here we specify the source directory, where we can do all the building and expect sources to be placed
S = "${WORKDIR}"

SYSTEMD_SERVICE_${PN} = "test_systemd.service"


#bitbake task
#created a directory /home/root for target install the script
do_install() {
             install -d ${D}/home/root
             install -m 0755 ${WORKDIR}/test_systemd.sh ${D}/home/root

             install -d ${D}{systemd_system_unitdir}
             install -m 0644 ${WORKDIR}/test_systemd.service ${D}{systemd_system_unitdir}
}

#Pack the path
FILES_${PN} += "/home/root"
FILES_${PN} += "/lib/systemd/system"

REQUIRED_DISTRO_FEATURES= "systemd"

The problem is when I try to bitbake system recipe, bitbake throws an error saying test_systemd.service not found. I managed to install both the files in RFS with a previous attempt but when I include the systemd concept. I get the no such file error. What could be the reason ? Error message

 NOTE: Executing SetScene Tasks
NOTE: Executing RunQueue Tasks
ERROR: service-0.1-r0 do_package: SYSTEMD_SERVICE_service value test_systemd.service does not exist
ERROR: service-0.1-r0 do_package: Function failed: systemd_populate_packages
ERROR: Logfile of failure stored in: /home/guest/yocto_practice/poky/build-beaglebone/tmp/work/cortexa8hf-neon-poky-linux-gnueabi/service/0.1-r0/temp/log.do_package.2860
ERROR: Task (/home/guest/yocto_practice/meta-testlayer/recipes-hello/service/service_0.1.bb:do_package) failed with exit code '1'
NOTE: Tasks Summary: Attempted 514 tasks of which 506 didn't need to be rerun and 1 failed.

Summary: 1 task failed:
  /home/guest/yocto_practice/meta-testlayer/recipes-hello/service/service_0.1.bb:do_package
Summary: There were 2 ERROR messages shown, returning a non-zero exit code.

Also is this the correct way to write bb recipe for systemd and what is the significance of writing this

#Pack the path
    FILES_${PN} += "/home/root"
    FILES_${PN} += "/lib/systemd/system"

without this bitbake throws error.

Answer 1

SYSTEMD_SERVICE_${PN} += "file://test_systemd.service"

This should be:

SYSTEMD_SERVICE_${PN} = "test_systemd.service"

Other notes (unrelated to the error):

• Installing things into /home is probably not a great idea (you could use e.g. ${libexecdir} for scripts that other scripts need.
• there's no reason for having a do_install_append() in a bb file: you can just put everything in do_install()
• If your Yocto is recent, using ${systemd_system_unitdir} instead of /lib/systemd/system is a good idea (in older releases ${systemd_unitdir}/system/ works)