Drop-in Files for systemd
As an alternative to adding applications to the barrier file, you can use drop-in files to configure the secfs-fs-barrier.service file for dependency management using systemd. This eliminates the need to modify the service file for configuring dependencies.
All drop-in directory files with the suffix .conf are merged in alphanumeric order and parsed after the main unit file has been parsed. Each drop-in file must contain appropriate section headers. Systemd reads the .conf files in the following order.
-
The instance
.d/subdirectory -
The template
.d/subdirectory
The drop-in .d/ directories for system services can be placed in the following directories:
-
/etc/systemd/system -
/usr/lib/systemd/system(Ubuntu only) -
/run/systemd/system
Drop-in files in /etc/ take precedence over those in the /run/ directory which, in turn, take precedence over those in the /usr/lib/ directory. Drop-in files in any of those directories take precedence over unit files wherever they are located. Multiple drop-in files with different names are applied in lexicographic order, regardless of which directories they reside in.
Following is an example of a drop-in file (dependencies.conf) for the secfs-fs-barrier.service:
cat /usr/lib/systemd/system/sec-fs-barrier.service.d/dependencies.conf
[Unit]
Before=mfetpd.service mfeespd.service
The above example displays a drop-in file which adds two McAfee related services in the Before= clause of the secfs-fs-barrier.service file without modifying the service file itself. Eventually, systemd detects the drop-in files and links them to the secfs-fs-barrier.service file.
