Improve prep and smoke test tooling

pikit-prep.sh

@@ -197,6 +197,40 @@ clean_home_dir() {
   fi
 }
 
+reset_iface_to_dhcp() {
+  local iface="$1"
+  local file="/etc/network/interfaces"
+  if [ ! -f "$file" ]; then
+    status SKIP "network config missing: $file"
+    return
+  fi
+  if ! grep -Eq "^[[:space:]]*iface[[:space:]]+$iface[[:space:]]+inet" "$file"; then
+    status SKIP "no iface config for $iface"
+    return
+  fi
+  local tmp
+  tmp="$(mktemp)"
+  awk -v target="$iface" '
+    BEGIN{in=0}
+    /^[[:space:]]*iface[[:space:]]+/ {
+      split($0, parts, /[[:space:]]+/);
+      if (parts[2]==target) { in=1; print "iface " target " inet dhcp"; next; }
+      else { in=0; }
+    }
+    {
+      if (in==1) {
+        if ($1=="address"||$1=="netmask"||$1=="gateway"||$1=="dns-nameservers") next;
+      }
+      print;
+    }' "$file" > "$tmp"
+  if mv "$tmp" "$file"; then
+    status CLEANED "forced DHCP for $iface in $file"
+  else
+    rm -f "$tmp" || true
+    status FAIL "update $file for $iface"
+  fi
+}
+
 prep_image() {
   section "Prep"
 
@@ -418,6 +452,10 @@ prep_image() {
   # --- DHCP leases ---
   clean_file /var/lib/dhcp/dhclient.eth0.leases
 
+  # --- Network config ---
+  reset_iface_to_dhcp eth0
+  reset_iface_to_dhcp wlan0
+
   # --- Nginx caches ---
   if [ -d /var/lib/nginx ]; then
     find /var/lib/nginx -mindepth 1 -maxdepth 1 -type d -exec rm -rf {} + 2>/dev/null
@@ -486,6 +524,20 @@ check_file_empty_or_missing() {
   fi
 }
 
+check_iface_dhcp() {
+  local iface="$1"
+  local file="/etc/network/interfaces"
+  if [ ! -f "$file" ]; then
+    status WARN "network config missing: $file"
+    return
+  fi
+  if grep -Eq "^[[:space:]]*iface[[:space:]]+$iface[[:space:]]+inet[[:space:]]+static" "$file"; then
+    status WARN "$iface set to static in $file"
+  else
+    status OK "$iface not static in $file"
+  fi
+}
+
 check_image() {
   section "Check"
 
@@ -595,6 +647,10 @@ check_image() {
   section "DHCP lease"
   check_file_missing /var/lib/dhcp/dhclient.eth0.leases
 
+  section "Network config"
+  check_iface_dhcp eth0
+  check_iface_dhcp wlan0
+
   section "Nginx cache dirs"
   if [ -d /var/lib/nginx ]; then
     local nginx_cache