Within the GNU/Linux distribution specific installation guides, the "Set
up Icinga DB" section was only excluded for openSUSE. However, since
there is an openSUSE installation guide within Icinga DB[^0], this is
not consistent. Thus, the if-guard was removed, resulting in this
section being available for each distribution. Windows is already
excluded through an if-guard above.
Some cases for Fedora were missing, which were also added.
[^0]: https://icinga.com/docs/icinga-db/latest/doc/02-Installation/openSUSE/
With Fedora 41, DNF was upgraded to version 5, breaking the command line
API of "dnf config-manager"[^0]. Unfortunately, DNF 5's addrepo does not
work with a simple URL anymore, but requires to construct a .repo file.
Furthermore, no information about trusting the Icinga signing key was
available, resulting in one being unable to install packages. This was
already the case for Fedora 40, still using DNF 4.
Since we are building Icinga DB for Fedora, I have included Icinga DB
documentation for Fedora. Otherwise, this section was empty.
Finally, the icingadb-redis-selinux package was mentioned for
distributions were we started to build SELinux packages for[^1].
[^0]: https://docs.fedoraproject.org/en-US/quick-docs/adding-or-removing-software-repositories-in-fedora/#_adding_repositories
[^1]: https://github.com/Icinga/icingadb/issues/580
We didn't really 'invent' unity builds, more like adopted them, since
this is a common practice.
Also added a reference to the actual CMake variable in question instead
of just alluding to it
You can only 'recognize' something you already know and 'another thing',
while not necessarily wrong does not seem right here when there isn't a
'first thing' to notice.
Reference the Check Result State Mapping table for the CheckResult state
field. This table covers both Service and Host states while the prior
documentation string only covered Services.
This change is useful since there are different kinds of states for
Hosts when using the Icinga 2 API. For one, there is a "normalized"
version of 0 for UP and 1 for DOWN. Then there is the exit code version
for 0/1 for UP and 2/3 for DOWN. Unfortunately, often this depends on
the context and sometimes even intermingles.
To make it obvious which kind of state one can expect for a CheckResult
object, I have linked to the already existing documentation section.
Other plugins list --extra-opts last as it's often some kind of feature of last
resort as it provides an option that can't be set in another way. For
consistency, this also moves it to the end for the curl check command.
First, the "--help" output from some sections was quite outdated,
sometimes manually patched. This resulted in incorrect and inconsistent
information, addressed by regenerating the output for each section based
on a current Icinga 2 version 2.14.4.
The two subsections about "--app" and "--library" were removed, as these
command line arguments were removed a while ago in
90496b5456b98ad4f9e0121272ccabfbbef11a91.
Otherwise, only minor changes have been made.
