Revert "coreos-teardown-initramfs: use NetworkManager to teardown net…

…working"

This reverts commit b8607da.

We're seeing around 75% failure rate with this patch when provisioning
RHCOS on AWS with m4 instance types. The error message is:

    Error: failed to set networking: Timeout was reached

I confirmed that D-Bus and NM are definitely still running when we issue
the `nmcli` call. Still, I think there's a subtle race somewhere (likely
combined with the specific network adapter of m4 instance types), that
we need to plug. We need more visibility into why NM isn't responding.
Anyway, for now let's revert this to not regress.

Fixes: https://issues.redhat.com/browse/OCPBUGS-17154
Probably fixes: https://issues.redhat.com/browse/OCPBUGS-19870

overlay.d/05core/usr/lib/dracut/modules.d/35coreos-ignition/coreos-teardown-initramfs.service

@@ -18,13 +18,13 @@ DefaultDependencies=false
 Before=ignition-mount.service
 Before=ignition-complete.target
 
-# Since we are tearing down networking using NetworkManager itself
-# we need to make sure NetworkManager is running. Similarly
-# dbus-broker since nmcli talks to the daemon via DBUS. Since the
-# ordering for ExecStop is the opposite of ExecStart we need to use
-# `After=` here.
-After=nm-initrd.service
-After=dbus-broker.service
+# Since we are tearing down networking we need to make sure
+# NetworkManager has been stopped, otherwise it'll be trying
+# to react to our delete/down operations. Since the ordering
+# for ExecStop is the opposite of ExecStart we need to use
+# `Before=nm-initrd.service`.
+# https://issues.redhat.com/browse/OCPBUGS-11052
+Before=nm-initrd.service
 
 # Make sure ExecStop= runs before we switch root
 Conflicts=initrd-switch-root.target umount.target

overlay.d/05core/usr/lib/dracut/modules.d/35coreos-ignition/coreos-teardown-initramfs.sh

@@ -182,15 +182,55 @@ propagate_ifname_udev_rules() {
     fi
 }
 
+down_interface() {
+    echo "info: taking down network device: $1"
+    # On recommendation from the NM team let's try to delete the device
+    # first and if that doesn't work then set it to down and flush any
+    # associated addresses. Deleting virtual devices (bonds, teams, bridges,
+    # ip-tunnels, etc) will clean up any associated kernel resources. A real
+    # device can't be deleted so that will fail and we'll fallback to setting
+    # it down and flushing addresses.
+    if ! ip link delete $1; then
+        ip link set $1 down
+        ip addr flush dev $1
+    fi
+}
+
+# Iterate through the interfaces in the machine and take them down.
+# Note that in the future we would like to possibly use `nmcli` networking off`
+# for this. See the following two comments for details:
+# https://github.com/coreos/fedora-coreos-tracker/issues/394#issuecomment-599721763
+# https://github.com/coreos/fedora-coreos-tracker/issues/394#issuecomment-599746049
+down_interfaces() {
+    if ! [ -z "$(ls /sys/class/net)" ]; then
+        for f in /sys/class/net/*; do
+            interface=$(basename "$f")
+            # The `bonding_masters` entry is not a true interface and thus
+            # cannot be taken down. Also skip local loopback
+            case "$interface" in
+                "lo" | "bonding_masters")
+                    continue
+                    ;;
+            esac
+            # When we start taking down devices some other devices can
+            # start to disappear (for example vlan on top of interface).
+            # If the device we're about to take down has disappeared
+            # since the start of this loop then skip taking it down.
+            if [ ! -e "$f" ]; then
+                echo "info: skipping teardown of ${interface}; no longer exists."
+                continue
+            fi
+            down_interface $interface
+        done
+    fi
+}
+
 main() {
     # Load libraries from dracut
     load_dracut_libs
 
-    # Take down all networking set up in the initramfs
-    if systemctl is-active --quiet nm-initrd.service; then
-        echo "info: taking down initramfs networking"
-        nmcli networking off
-    fi
+    # Take down all interfaces set up in the initramfs
+    down_interfaces
 
     # Clean up all routing
     echo "info: flushing all routing"
@@ -209,13 +249,10 @@ main() {
         propagate_ifname_udev_rules
     fi
 
-    # Configuration has been propagated, but we can't clean up
-    # /run/NetworkManager because NM is still running. Let's drop
-    # down a tmpfiles.d snippet so that it's cleaned up first thing
-    # in the real root. Doing it this way prevents us having to write
-    # another unit to do the cleanup after this service has finished.
-    echo "R! /run/NetworkManager - - - - -" > \
-        /run/tmpfiles.d/15-teardown-initramfs-networkmanager.conf
+    # Now that the configuration has been propagated (or not)
+    # clean it up so that no information from outside of the
+    # real root is passed on to NetworkManager in the real root
+    rm -rf /run/NetworkManager/
 
     rm -f /run/udev/rules.d/80-coreos-boot-disk.rules
     rm -f /dev/disk/by-id/coreos-boot-disk