qm: document systemd drop-in plus QM

The spec file change for AllowedCPU won't affect ostree systems. This patch will document about using systemd drop-in plus QM. Signed-off-by: Douglas Schilling Landgraf <[email protected]>
containers · Nov 30, 2023 · aa080c3 · aa080c3
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diff --git a/qm.8.md b/qm.8.md
@@ -129,6 +129,22 @@ If you want permanently modify the bluechi agent within the QM you can add confi
 /usr/lib/qm/rootfs/etc/bluechi/agent.conf.d/ directory or modify the /etc/containers/systemd/qm.container
 quadlet file to not execute the bluechi-agent setup script.
 
+## Using systemd drop-in with QM
+
+The systemd drop-in feature allows users to extend or modify the configuration of systemd units without directly editing the unit files provided by the system package.
+
+In this example, we will add the AllowedCPU to set as 1 to qm.service that quadlet generated:
+
+**Create allowedcpus.conf**
+
+```console
+cat  /etc/systemd/system/qm.service.d/allowedcpus.conf
+
+# Contents of qm.continer.d/allowedcpus.conf
+[Service]
+AllowedCPUs=1
+```
+
 ## SEE ALSO
 
 **[podman(1)](https://github.com/containers/podman/blob/main/docs/source/markdown/podman.1.md)**,**[quadlet(5)](https://github.com/containers/podman/blob/main/docs/source/markdown/podman-systemd.unit.5.md)**, systemctl(1), systemd(1), dnf(8), [bluechi-agent(1)](https://github.com/containers/bluechi/blob/main/doc/man/bluechi-agent.1.md),[bluechi-agent.conf.5](https://github.com/containers/bluechi/blob/main/doc/man/bluechi-agent.conf.5.md)
diff --git a/qm.container b/qm.container
@@ -2,7 +2,8 @@
 WantedBy=default.target
 
 [Service]
-AllowedCPUs=1
+# It's recommended to use systemd drop-in to override the
+# systemd settings. See QM manpage for an example.
 CPUWeight=50
 Delegate=true
 IOWeight=50

diff --git a/rpm/qm.spec b/rpm/qm.spec
@@ -104,17 +104,6 @@ sed -i 's/^install: man all/install:/' Makefile
 %_format MODULES %{_datadir}/selinux/packages/$x.pp.bz2
 %selinux_modules_install -s %{selinuxtype} $MODULES
 
-# Set AllowedCPUs in quadlet file
-NPROC=$(nproc)
-if [[ $NPROC == 1 ]]; then
-    ALLOWED_CPUS=0
-elif [[ $NPROC == 2 ]]; then
-    ALLOWED_CPUS=1
-else
-    ALLOWED_CPUS=$(expr $NPROC / 2)"-"$(expr $NPROC - 1)
-fi
-sed "s/^AllowedCPUs=.*/AllowedCPUs=$ALLOWED_CPUS/" %{_datadir}/containers/systemd/%{name}.container > %{_sysconfdir}/containers/systemd/%{name}.container
-
 %postun
 if [ $1 -eq 0 ]; then
    %selinux_modules_uninstall -s %{selinuxtype} %{modulenames}