Bug 2049296

Description of problem:
If a process modifies /etc/rhsm/rhsm.conf (say by running the sed command on it) changes to this file will not be reflected in output of follow-up Get()/GetAll() calls over the RHSM DBus interface.

Only after restarting the rhsm.service systemd unit, the changes are visible in the DBus call output.

Version-Release number of selected component (if applicable):
subscription-manager-1.29.21-1.el9.x86_64
running on the
RHEL-9.0.0-20220119.0-BaseOS-x86_64-boot.iso

How reproducible:
always

Steps to Reproduce:

0. prepare the environment
- download RHEL-9.0.0-20220119.0-BaseOS-x86_64-boot.iso or similar with subscription-manager-1.29.21-1.el9.x86_64, 
- use inst.sshd boot option to enable SSH access to the installation environment when booting the image
- once it boots up, switch to TTY2 and run "ip a" to find what ip address the VM got
- connect to the ip address as root via SSH for easy access
(This is the environment where I debugged this, most likely the issue will also be replicable on an installed system with the same RHSM version.)

1. create a local copy of "clean" rhsm.conf:
cp /etc/rhsm/rhsm.conf rhsm.conf_backup

2. put the following script into a file and run it:


#!/bin/bash
echo "** stopping rhsm.service **"
systemctl stop rhsm.service
echo "** resetting rhsm.conf **"
cp rhsm.conf_backup /etc/rhsm/rhsm.conf
echo "** starting rhsm.service **"
systemctl start rhsm.service
echo "** using sed to change server.hostname in rhsm.conf **"
sed -i "s/^hostname\s*=.*/hostname = FOO/g" /etc/rhsm/rhsm.conf
echo "** using DBus Get() method to get values use server.hostname **"
busctl call com.redhat.RHSM1 /com/redhat/RHSM1/Config com.redhat.RHSM1.Config Get ss "server.hostname" ""
echo "** checking hostname key in /etc/rhsm/rhsm.conf **"
cat /etc/rhsm/rhsm.conf | grep -e "^hostname ="
echo "** using DBus GetAll() to list all values **"
busctl call com.redhat.RHSM1 /com/redhat/RHSM1/Config com.redhat.RHSM1.Config GetAll s ""
echo "** restarting rhsm.service **"
systemctl restart rhsm.service
echo "** trying again after rhsm.service restart **"
echo "** using DBUS Get() method to get values use server.hostname - after rhsm.service restart **"
busctl call com.redhat.RHSM1 /com/redhat/RHSM1/Config com.redhat.RHSM1.Config Get ss "server.hostname" ""
echo "** checking hostname key in /etc/rhsm/rhsm.conf - after rhsm.service restart **"
cat /etc/rhsm/rhsm.conf | grep -e "^hostname ="
echo "** using DBus GetAll() to list all values - after rhsm.service restart **"
busctl call com.redhat.RHSM1 /com/redhat/RHSM1/Config com.redhat.RHSM1.Config GetAll s ""


3. Note that the change to the server.hostname key done via sed is not "visible" over DBus until the rhsm.service is restarted.

4. For comparison I've created a variant of the script using subscription-manager config instead of sed:


#!/bin/bash
echo "** stopping rhsm.service **"
systemctl stop rhsm.service
echo "** resetting rhsm.conf **"
cp rhsm.conf_backup /etc/rhsm/rhsm.conf
echo "** starting rhsm.service **"
systemctl start rhsm.service
echo "** using subscription-manager config --server.hostname to set server.hostname **"
subscription-manager config --server.hostname BAR
echo "** using DBus Get() method to get values use server.hostname **"
busctl call com.redhat.RHSM1 /com/redhat/RHSM1/Config com.redhat.RHSM1.Config Get ss "server.hostname" ""
echo "** checking hostname key in /etc/rhsm/rhsm.conf **"
cat /etc/rhsm/rhsm.conf | grep -e "^hostname ="
echo "** using DBus GetAll() to list all values **"
busctl call com.redhat.RHSM1 /com/redhat/RHSM1/Config com.redhat.RHSM1.Config GetAll s ""
echo "** restarting rhsm.service **"
systemctl restart rhsm.service
echo "** trying again after rhsm.service restart **"
echo "** using DBUS Get() method to get values use server.hostname - after rhsm.service restart **"
busctl call com.redhat.RHSM1 /com/redhat/RHSM1/Config com.redhat.RHSM1.Config Get ss "server.hostname" ""
echo "** checking hostname key in /etc/rhsm/rhsm.conf - after rhsm.service restart **"
cat /etc/rhsm/rhsm.conf | grep -e "^hostname ="
echo "** using DBus GetAll() to list all values - after rhsm.service restart **"
busctl call com.redhat.RHSM1 /com/redhat/RHSM1/Config com.redhat.RHSM1.Config GetAll s ""


5. Note that this time the server.hostname change is visible immediately.


To summarize, RHSM DBus API should either reflect changes to the config file in follow-up DBus calls or at least this behaviour should be documented as intentional.

Also at the moment due to this behaviour the Anaconda installer needs to always restart rhsm.service during registration to a Satellite instance, because the satellite bootstrap script currently uses sed to directly change values in rhsm.conf. Without rhsm.service being restarted, these changes would not be taken into account by RHSM and the registration attempt would fail (RHSM would try to connect to hosted Candlepin with the provided credentials instead of to the given Satellite instance).

This results in the Anaconda code being more complex (as we need to make sure rhsm.service is restarted) and the registration attempt taking longer (as we need to wait for the rhsm.service to restart).