feat(network-manager): run as daemon with D-Bus

This commit changes how NM is started inside the initrd. Instead of running NM
in the special --configure-and-quit=initrd mode, which sets up network and
quits, start it as a daemon.

This has multiple advantages. First, we no longer need to run NM in a special
mode that requires additional code and maintenance. NetworkManager works
exactly as in the real root.

One problem of the current configure-and-quit approach is that once NM has
quit, dynamic addresses can expire if the initrd setup takes longer than the
DHCP lease interval or than the IPv6 address lifetime. Running NM as a service
solves this problem.

Now NM runs with D-Bus support and therefore its API can be used by other
modules. This open the possibility, for example, to integrate nm-cloud-setup to
automatically configure networking based on cloud metadata.

Use the NetworkManager-wait-online.service, ordered before
dracut-initqueue.service, to delay the initqueue until NM has terminated its
configuration.

modules.d/35network-manager/initrd-no-auto-default.conf

@@ -0,0 +1,5 @@
+[.config]
+enable=env:initrd
+
+[main]
+no-auto-default=*

modules.d/35network-manager/module-setup.sh

@@ -10,6 +10,7 @@ check() {
 
 # called by dracut
 depends() {
+    echo dbus
     return 0
 }
 
@@ -33,8 +34,18 @@ install() {
     inst_multiple -o teamd dhclient
     inst_hook cmdline 99 "$moddir/nm-config.sh"
     if dracut_module_included "systemd"; then
-        inst_simple "${moddir}/nm-run.service" "${systemdsystemunitdir}/nm-run.service"
-        $SYSTEMCTL -q --root "$initdir" enable nm-run.service
+
+        inst "$dbussystem"/org.freedesktop.NetworkManager.conf
+        inst_multiple nmcli nm-online
+
+        # Install a configuration snippet to prevent the automatic creation of
+        # "Wired connection #" DHCP connections for Ethernet interfaces
+        inst_simple "$moddir"/initrd-no-auto-default.conf /usr/lib/NetworkManager/conf.d/
+
+        inst_simple "$moddir"/nm-initrd.service "$systemdsystemunitdir"/nm-initrd.service
+        inst_simple "$moddir"/nm-wait-online-initrd.service "$systemdsystemunitdir"/nm-wait-online-initrd.service
+
+        $SYSTEMCTL -q --root "$initdir" enable nm-initrd.service
     fi
 
     inst_hook initqueue/settled 99 "$moddir/nm-run.sh"

modules.d/35network-manager/nm-config.sh

@@ -10,6 +10,9 @@ if getargbool 0 rd.debug -d -y rdinitdebug -d -y rdnetdebug; then
     # shellcheck disable=SC2174
     mkdir -m 0755 -p /run/NetworkManager/conf.d
     (
+        echo '[.config]'
+        echo 'enable=env:initrd'
+        echo
         echo '[logging]'
         echo 'level=TRACE'
     ) > /run/NetworkManager/conf.d/initrd-logging.conf

modules.d/35network-manager/nm-initrd.service

@@ -0,0 +1,26 @@
+[Unit]
+DefaultDependencies=no
+Wants=systemd-udev-settle.service
+After=systemd-udev-settle.service
+Before=network.target
+ConditionPathExists=/run/NetworkManager/initrd/neednet
+ConditionPathExistsGlob=|/usr/lib/NetworkManager/system-connections/*
+ConditionPathExistsGlob=|/run/NetworkManager/system-connections/*
+ConditionPathExistsGlob=|/etc/NetworkManager/system-connections/*
+ConditionPathExistsGlob=|/etc/sysconfig/network-scripts/ifcfg-*
+
+[Service]
+Type=dbus
+BusName=org.freedesktop.NetworkManager
+ExecReload=/usr/bin/busctl call org.freedesktop.NetworkManager /org/freedesktop/NetworkManager org.freedesktop.NetworkManager Reload u 0
+ExecStart=/usr/sbin/NetworkManager --debug
+KillMode=process
+StandardOutput=tty
+Environment=NM_CONFIG_ENABLE_TAG=initrd
+Restart=on-failure
+ProtectSystem=true
+ProtectHome=read-only
+
+[Install]
+WantedBy=initrd.target
+Also=nm-wait-online-initrd.service

modules.d/35network-manager/nm-lib.sh

@@ -14,7 +14,7 @@ nm_generate_connections() {
             /etc/sysconfig/network-scripts/ifcfg-*; do
             [ -f "$i" ] || continue
             echo '[ -f /tmp/nm.done ]' > "$hookdir"/initqueue/finished/nm.sh
-            : > /run/NetworkManager/initrd/neednet # activate nm-run.service
+            : > /run/NetworkManager/initrd/neednet # activate NM services
             break
         done
     fi

modules.d/35network-manager/nm-wait-online-initrd.service

@@ -0,0 +1,17 @@
+[Unit]
+DefaultDependencies=no
+Requires=nm-initrd.service
+After=nm-initrd.service
+Before=network-online.target
+Before=dracut-initqueue.service
+ConditionPathExists=/run/NetworkManager/initrd/neednet
+
+[Service]
+Type=oneshot
+ExecStart=/usr/bin/nm-online -s -q
+RemainAfterExit=yes
+Environment=NM_ONLINE_TIMEOUT=3600
+
+[Install]
+WantedBy=initrd.target
+WantedBy=network-online.target