[arch-projects] [netcfg] [PATCH 3/3] systemd: add alternative units with proper dependencies

[Thomas Bächler]

Until now, netcfg might fail to start because it is started too early (this actually
happened to me quite regularly). To fix this, we need to make systemd aware of the
dependencies of a profile.

This commit adds a systemd generator that creates profiles with the names
   netcfg-profile-$PROFILE.service
on boot. The ugly part: You cannot permanently enable such a profile, as
it is generated during boot. To enable it, put it in NETWORKS=() in
/etc/conf.d/netcfg and run
   systemctl enable netcfg-profiles.target
If you add a new profile, you need to reload the systemd configuration
so the service file shows up.

While this scheme is less intuitive than netcfg at profilename.service, it
is the only way to provide proper dependencies during boot.

Due to a bug in systemd's dependency resolution with devices, this patch
requires systemd v195 to work.
---
 Makefile                       |  2 ++
 systemd/netcfg-generator       | 58 ++++++++++++++++++++++++++++++++++++++++++
 systemd/netcfg-profiles.target |  5 ++++
 3 files changed, 65 insertions(+)
 create mode 100755 systemd/netcfg-generator
 create mode 100644 systemd/netcfg-profiles.target

diff --git a/Makefile b/Makefile
index bbada3f..3a80c41 100644
--- a/Makefile
+++ b/Makefile
@@ -37,7 +37,9 @@ install: install-docs
 	install -d $(DESTDIR)/usr/lib/systemd/system
 	install -m644 \
 	    systemd/*.service \
+	    systemd/*.target \
 	    $(DESTDIR)/usr/lib/systemd/system/
+	install -Dm755 systemd/netcfg-generator /usr/lib/systemd/system-generators/netcfg-generator
 
 install-docs: docs
 	install -d $(DESTDIR)/usr/share/man/{man5,man8}
diff --git a/systemd/netcfg-generator b/systemd/netcfg-generator
new file mode 100755
index 0000000..983dceb
--- /dev/null
+++ b/systemd/netcfg-generator
@@ -0,0 +1,58 @@
+#!/bin/bash
+
+[[ -d $1 ]] || exit 1
+
+. /usr/lib/network/network
+
+profile_tmpl_unit="[Unit]
+Description=Netcfg networking service for profile @PROFILE@
+SourcePath=/etc/network.d/@PROFILE@
+Before=network.target
+Wants=network.target"
+
+profile_tmpl_service="[Service]
+Type=oneshot
+RemainAfterExit=yes
+ExecStart=/usr/bin/netcfg check-iface @PROFILE@
+ExecStop=-/usr/bin/netcfg down @PROFILE@
+KillMode=none"
+
+for pf in /etc/network.d/*; do
+    [[ -f ${pf} && -r ${pf} ]] || continue
+    p=${pf#/etc/network.d/}
+    load_profile ${p}
+    systemd_devices=
+    case ${CONNECTION} in
+        bond)
+            for iface in ${SLAVE_INTERFACES[@]}; do
+                systemd_devices="${systemd_devices}sys-subsystem-net-devices-${iface}.device "
+            done
+            ;;
+        bridge)
+            for iface in ${BRIDGE_INTERFACES[@]}; do
+                systemd_devices="${systemd_devices}sys-subsystem-net-devices-${iface}.device "
+            done
+            ;;
+        ethernet|pppoe|wireless)
+            systemd_devices="sys-subsystem-net-devices-${INTERFACE}.device"
+            ;;
+        vlan)
+            systemd_devices="sys-subsystem-net-devices-${VLAN_PHYS_DEV}.device"
+            ;;
+    esac
+    systemd_devices=${systemd_devices% }
+    if [[ ${systemd_devices} ]]; then
+        bindsto="BindsTo=${systemd_devices}"
+        after="After=${systemd_devices}"
+    else
+        bindsto=
+        after=
+    fi
+    echo -e "${profile_tmpl_unit//@PROFILE@/$p}\n${bindsto}\n${after}\n\n${profile_tmpl_service//@PROFILE@/$p}" > $1/netcfg-profile-$p.service
+done
+
+. /etc/conf.d/netcfg
+mkdir $1/netcfg-profiles.target.wants
+for network in "${NETWORKS[@]}"; do
+    ln -s $1/netcfg-profile-$p.service $1/netcfg-profiles.target.wants/netcfg-profile-$p.service
+done
diff --git a/systemd/netcfg-profiles.target b/systemd/netcfg-profiles.target
new file mode 100644
index 0000000..ba310fa
--- /dev/null
+++ b/systemd/netcfg-profiles.target
@@ -0,0 +1,5 @@
+[Unit]
+Description=Netcfg network profiles
+
+[Install]
+WantedBy=multi-user.target
-- 
1.8.0