nm-in-container: disable handling of "/etc/resolv.conf" in container and use 8.8.8.8.

By default, podman bind mounts a "/etc/resolv.conf" file. That prevents
NetworkManager (inside the container) to update the file, which leads to
warnings in the log and certain NM-ci tests won't pass due to that.

Disable handling of "/etc/resolv.conf" in podman. But also pre-deploy a
default resolv.conf, with the google name server 8.8.8.8.  I don't
understand why, but even with "--dns=none", writing "/etc/resolv.conf"
while building the container doesn't take effect.  Instead, write a
usable "/etc/resolv.conf" from "/etc/rc.d/rc.local".

contrib/scripts/nm-in-container.d/data-etc-rc.local

@@ -1,3 +1,8 @@
 #!/bin/bash -e
 
 /usr/bin/_nm-in-container-setup.sh
+
+cat <<EOF > /etc/resolv.conf
+# Generated by /etc/rc.d/rc.local
+nameserver 8.8.8.8
+EOF

contrib/scripts/nm-in-container.d/data-nm-env-prepare.sh

@@ -83,6 +83,8 @@ do_setup() {
             --listen-address="192:168:$((120 + IDX))::1" \
             --dhcp-range="192.168.$((120 + $IDX)).100,192.168.$((120 + $IDX)).150,2m" \
             --dhcp-range="192:168:$((120 + IDX))::1:1000,192:168:$((120 + IDX))::1:2000,64,2m" \
+            --dhcp-option=option:dns-server,8.8.8.8,8.8.4.4 \
+            --dhcp-option=option6:dns-server \
             --no-ping \
             &
 

contrib/scripts/nm-in-container.sh

@@ -497,6 +497,8 @@ RUN systemctl enable NetworkManager
 # Generate a stable machine id.
 RUN echo "10001000100010001000100010001000" > /etc/machine-id
 
+RUN echo -e "# Default from the container image\nnameserver 8.8.8.8" > /etc/resolv.conf
+
 # Generate a fixed (version 1) secret key.
 RUN mkdir -p /var/lib/NetworkManager
 RUN chmod 700 /var/lib/NetworkManager
@@ -569,6 +571,7 @@ do_run() {
 
         podman run --privileged \
             --name "$CONTAINER_NAME_NAME" \
+            --dns=none \
             -d \
             -v "$BASEDIR_NM:$BASEDIR_NM" \
             "${BIND_NM_CI[@]}" \