Centos – Wait for systemd oneshot service to finish

centoscentos7redhatsystemd

I am doing some server provisioning and I need to run a script AFTER installation as it requires the system to be fully functional, include services. So I cannot put it inside the %post section of my kickstart file.

Instead I have created a systemd service which disables itself as the last thing it does.

[Unit]
Description=Prepare the system after installation

[Service]
Type=oneshot
ExecStart=/usr/bin/prepare-system

[Install]
WantedBy=multi-user.target

The problem is that during the first boot, I get to the login prompt and can even login and start using the system, while the "first boot script" is still running.

This gives the Administrator setting up the system the illusion that the system is finished, when it's really not.

I would instead want the service to delay the booting, preferably showing a message like "The system is being prepared, please wait…" and wait there until the script is finished.

Best Answer

Found the answer here: https://unix.stackexchange.com/questions/216045/systemd-configure-unit-file-so-that-login-screen-is-not-shown-until-service-exi

Just set Before to when the terminal is available:

[Unit]
Description=Prepare the system after installation
Before=getty@tty1.service getty@tty2.service getty@rrt3.service getty@tty4.service getty@tty5.service getty@tty6.service

[Service]
Type=oneshot
ExecStart=/usr/bin/prepare-system

[Install]
WantedBy=multi-user.target

Related Solutions

Systemd – How to Set Environment Variable in Service

Times change and so do best practices.

The current best way to do this is to run systemctl edit myservice, which will create an override file for you or let you edit an existing one.

In normal installations this will create a directory /etc/systemd/system/myservice.service.d, and inside that directory create a file whose name ends in .conf (typically, override.conf), and in this file you can add to or override any part of the unit shipped by the distribution.

For instance, in a file /etc/systemd/system/myservice.service.d/myenv.conf:

[Service]
Environment="SECRET=pGNqduRFkB4K9C2vijOmUDa2kPtUhArN"
Environment="ANOTHER_SECRET=JP8YLOc2bsNlrGuD6LVTq7L36obpjzxd"

Also note that if the directory exists and is empty, your service will be disabled! If you don't intend to put something in the directory, ensure that it does not exist.

For reference, the old way was:

The recommended way to do this is to create a file /etc/sysconfig/myservice which contains your variables, and then load them with EnvironmentFile.

For complete details, see Fedora's documentation on how to write a systemd script.

Chaining custom systemd services

Your got it backwards. After does not specify that service Cneeds to be started, see systemd.unit for more information.

You want something like that as your configuration for service B:

[Unit]
Description=Your service C
Requires=C.service
Before=C.service
...

Best Answer

Related Solutions

Systemd – How to Set Environment Variable in Service

Chaining custom systemd services

Related Topic