[PATCH v2] Add /etc/resolve.conf to kdump initrd if it's managed manually

[Coiby Xu]

Resolves: https://issues.redhat.com/browse/RHEL-11897

Some users may choose to manage /etc/resolve.conf manually (e.g. by
setting dns=none in NetworkManager.conf [1]). In this case, network
dumping will not work because DNS resolution doesn't work. Copy
/etc/resolve.conf to kdump initrd if this file is not managed by
systemd-resolved or NetworkManager.

[1] https://bugzilla.gnome.org/show_bug.cgi?id=690404

Fixes: 63c3805c ("Set up kdump network by directly copying NM connection profile to
initrd")
Reported-by: Curtis Taylor <cutaylor(a)redhat.com&gt;
Cc: Jie Li <jieli(a)redhat.com&gt;
Signed-off-by: Coiby Xu <coxu(a)redhat.com&gt;
---
v2
 - use 'grep "\|"' instead of 'grep | grep' for multiple
patterns
	  matching
	- improve commit message
---
 dracut-module-setup.sh | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/dracut-module-setup.sh b/dracut-module-setup.sh
index ff53d084..d062f7fd 100755
--- a/dracut-module-setup.sh
+++ b/dracut-module-setup.sh
@@ -563,6 +563,19 @@ kdump_collect_netif_usage() {
     fi
 }
 
+kdump_install_resolv_conf() {
+
+    local _resolv_conf=/etc/resolv.conf
+
+    # Some users may choose to manage /etc/resolve.conf manually.
+    #
+    # We can tell this case by confirming this file is not manged by
+    # systemd-resolved or NetworkManager.
+    if ! grep -qs "^nameserver 127.0.0.53\|^# Generated by NetworkManager"
"$_resolv_conf"; then
+        dracut_install "$_resolv_conf"
+    fi
+}
+
 # Setup dracut to bring up network interface that enable
 # initramfs accessing giving destination
 kdump_install_net() {
@@ -575,6 +588,7 @@ kdump_install_net() {
         kdump_setup_znet
         kdump_install_nm_netif_allowlist "$_netifs"
         kdump_install_nic_driver "$_netifs"
+        kdump_install_resolv_conf
     fi
 }
 
-- 
2.41.0