Use the FQDN instead of the hostname

[sbernhard]

The socket.gethostname() method is not safe to return the FQDN for different operating system.

Debian12

root@debian12:~# cat /etc/os-release 
PRETTY_NAME="Debian GNU/Linux 12 (bookworm)"
NAME="Debian GNU/Linux"
VERSION_ID="12"
VERSION="12 (bookworm)"
VERSION_CODENAME=bookworm
ID=debian
HOME_URL="https://www.debian.org/"
SUPPORT_URL="https://www.debian.org/support"
BUG_REPORT_URL="https://bugs.debian.org/"
root@debian12:~# python3 test.py 
hostname is debian12
fqdn is debian12.master.dev.atix

Ubuntu

root@ubuntu2204:~# cat /etc/os-release 
PRETTY_NAME="Ubuntu 22.04.3 LTS"
NAME="Ubuntu"
VERSION_ID="22.04"
VERSION="22.04.3 LTS (Jammy Jellyfish)"
VERSION_CODENAME=jammy
ID=ubuntu
ID_LIKE=debian
HOME_URL="https://www.ubuntu.com/"
SUPPORT_URL="https://help.ubuntu.com/"
BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
UBUNTU_CODENAME=jammy
root@ubuntu2204:~# python3 test.py 
hostname is ubuntu2204
fqdn is ubuntu2204.master.dev.atix

RockyLinux

[root@or ~]# cat /etc/os-release 
NAME="Rocky Linux"
VERSION="8.9 (Green Obsidian)"
ID="rocky"
ID_LIKE="rhel centos fedora"
VERSION_ID="8.9"
PLATFORM_ID="platform:el8"
PRETTY_NAME="Rocky Linux 8.9 (Green Obsidian)"
ANSI_COLOR="0;32"
LOGO="fedora-logo-icon"
CPE_NAME="cpe:/o:rocky:rocky:8:GA"
HOME_URL="https://rockylinux.org/"
BUG_REPORT_URL="https://bugs.rockylinux.org/"
SUPPORT_END="2029-05-31"
ROCKY_SUPPORT_PRODUCT="Rocky-Linux-8"
ROCKY_SUPPORT_PRODUCT_VERSION="8.9"
REDHAT_SUPPORT_PRODUCT="Rocky Linux"
REDHAT_SUPPORT_PRODUCT_VERSION="8.9"
[root@or ~]# /usr/libexec/platform-python test.py 
hostname is or
fqdn is or.master.dev.atix

AlmaLinux

[root@almalinux8 ~]# cat /etc/os-release 
NAME="AlmaLinux"
VERSION="8.9 (Midnight Oncilla)"
ID="almalinux"
ID_LIKE="rhel centos fedora"
VERSION_ID="8.9"
PLATFORM_ID="platform:el8"
PRETTY_NAME="AlmaLinux 8.9 (Midnight Oncilla)"
ANSI_COLOR="0;34"
LOGO="fedora-logo-icon"
CPE_NAME="cpe:/o:almalinux:almalinux:8::baseos"
HOME_URL="https://almalinux.org/"
DOCUMENTATION_URL="https://wiki.almalinux.org/"
BUG_REPORT_URL="https://bugs.almalinux.org/"

ALMALINUX_MANTISBT_PROJECT="AlmaLinux-8"
ALMALINUX_MANTISBT_PROJECT_VERSION="8.9"
REDHAT_SUPPORT_PRODUCT="AlmaLinux"
REDHAT_SUPPORT_PRODUCT_VERSION="8.9"
[root@almalinux8 ~]# /usr/libexec/platform-python test.py 
hostname is almalinux8.master.dev.atix
fqdn is almalinux8.master.dev.atix

Oracle

SLES

sles15sp5:~ # cat /etc/os-release 
NAME="SLES"
VERSION="15-SP5"
VERSION_ID="15.5"
PRETTY_NAME="SUSE Linux Enterprise Server 15 SP5"
ID="sles"
ID_LIKE="suse"
ANSI_COLOR="0;32"
CPE_NAME="cpe:/o:suse:sles:15:sp5"
DOCUMENTATION_URL="https://documentation.suse.com/"
sles15sp5:~ # python3 test.py 
hostname is sles15sp5
fqdn is sles15sp5.master.dev.atix

As you see, even on EL variants like Rocky Linux the hostname is returend instead of the fqdn. Therefore, the suggestion is to use socket.getfqdn() instead of socket.gethostname() to make sure, the FQDN is used for all OS.

Test script on all systems was:

import socket
print("hostname is %s" % socket.gethostname())
print("fqdn is %s" % socket.getfqdn())

[jirihnidek]

Thanks for the PR, but I'm still missing the reason, why do you want to have such change? Are these hostnames displayed anywhere in a web UI of Satellite and it is confusing?

Administrator can set hostname to any string using e.g. hostnamectl. There are many systems without any FQDN...

Documentation of socket.getfqdn() says:

Help on function getfqdn in module socket:

getfqdn(name='')
    Get fully qualified domain name from name.

    An empty argument is interpreted as meaning the local host.

    First the hostname returned by gethostbyaddr() is checked, then
    possibly existing aliases. In case no FQDN is available and `name`
    was given, it is returned unchanged. If `name` was empty, '0.0.0.0' or '::',
    hostname from gethostname() is returned.

I see risks of accepting such change, because hostnames are displayed e.g. in the web UI on console.redhat.com and re-registration of system would change displayed name of systems. Such change could be confusing for users of console.redhat.com.

NOTE: We also send fqdn in system facts during registration.

[sbernhard]

Make sense. Will close this PR. thanks for your fast feedback @jirihnidek