Ensure the cache directory exists

[ekohl]

As suggested in #4414

Fixes GH-4414

[dnsmichi]

Looks good to me. I'd like to test that a little further before merging this into a bugfix release.

[dnsmichi]

Thanks 👍

[oliver]

Is it necessary to use mode 750 for the cache directory, or would mode 755 be acceptable as well for you?

After upgrading to Icinga 2.7.1 my /var/cache/icinga2/ directory is readable only for nagios user and nagios group; but icinga2-classicui runs as user www-data so it cannot access the /var/cache/icinga2/objects.cache file and shows "Error: Could not read object configuration data" in browser. Changing the directory mode to 755 fixed this.

I'm not sure if the .deb packages had originally created /var/cache/icinga2/ with mode 755 or if I manually made that change during initial setup and forgot to document it. But if there's no harm done by setting the directory mode to 755 it would be nice if you could change that for future releases. Also, if you have alternative suggestions how to set this up (icinga2-classicui running as www-data but /var/cache/icinga2/ only accessible for nagios user/group) I'd appreciate that.

This happened with icinga2 2.7.1-1.jessie as installed from https://packages.icinga.com/debian/.

[lazyfrosch]

@oliver the packaging sets this per default:

https://github.com/Icinga/icinga-packaging/blob/deb/release/icinga2/jessie/debian/icinga2-common.postinst#L54

Unfortunatly prepare-dirs does not the same here...

[ekohl]

@lazyfrosch looks like a tmpfiles.d solution for systemd-based systems is still the cleaner route to take.