Using systemd drop-in file for salt-minion.service override

[petiepooo]

Replacing the upstream packager's service file can lead to subtle bugs if an upstream change goes unnoticed. For example, at

securityonion/salt/salt/service/salt-minion.service.jinja

Line 12 in 484aa7b

ExecStartPre=/bin/sleep {{ salt['pillar.get']('salt:minion:service_start_delay', service_start_delay) }}

it appears the upstream salt-minion.service file is replaced in order to add a 30 second startup delay.

This is probably better accomplished by creating a drop-in file at say /etc/systemd/system/salt-minion.service.d/start-delay.conf containing just the results of jinja processing the following:

[Service]
ExecStartPre=/bin/sleep {{ salt['pillar.get']('salt:minion:service_start_delay', service_start_delay) }}

and leaving the upstream packager's service file in /lib/systemd/system active.

An example of a subtle bug: SaltStack changed their base URL from saltstack.com to saltproject.io, but the documentation reference has not been updated in your copy of their service file. This results in the (harmless now but maybe not so in the future) salt output during so-setup of

[INFO ] Executing state file.managed for [/etc/systemd/system/multi-user.target.wants/salt-minion.service]
[INFO ] Fetching file from saltenv 'base', ** done ** 'salt/service/salt-minion.service.jinja'
[INFO ] File changed:
---
+++
@@ -1,6 +1,6 @@
[Unit]
Description=The Salt Minion
-Documentation=man:salt-minion(1) file:///usr/share/doc/salt/html/contents.html https://docs.saltproject.io/en/latest/contents.html
+Documentation=man:salt-minion(1) file:///usr/share/doc/salt/html/contents.html https://docs.saltstack.com/en/latest/contents.html
After=network.target salt-master.service

[Service]
@@ -9,6 +9,7 @@
NotifyAccess=all
LimitNOFILE=8192
ExecStart=/usr/bin/salt-minion
+ExecStartPre=/bin/sleep 30

[Install]
-WantedBy=multi-user.target
+WantedBy=multi-user.target
[INFO ] Completed state [/etc/systemd/system/multi-user.target.wants/salt-minion.service] at time 15:01:42.444921 (duration_in_ms=17.01)

For more details on using systemd's drop-in unit files, search for the keyword 'drop-in' in the manpage at https://www.freedesktop.org/software/systemd/man/systemd.unit.html

[dougburks]

Created issue #8441