fix incorrect behavior for -s and [variants] parameter

Signed-off-by: Harta Angkasa <24356946+ItsHarta@users.noreply.github.com>

Author: ItsHarta

functions.sh

@@ -69,7 +69,7 @@ function get_variants() {
   if [ ${#variantsfilter[@]} -gt 0 ]; then
     for variant1 in "${availablevariants[@]}"; do
       for variant2 in "${variantsfilter[@]}"; do
-        if [ "${variant1}" = "${variant2}" ]; then
+        if [[ "${variant1}" =~ ^"${variant2}" ]]; then
           variants+=("${variant1}")
         fi
       done
@@ -365,4 +365,4 @@ function tests_updated() {
     return 1
   fi
   return 0
-}
+}

update.sh

@@ -130,6 +130,14 @@ function update_node_version() {
     fi
 
     nodeVersion="${version}.${fullVersion:-0}"
+    
+    # preserve the existing YARN_VERSION
+    if [ "${SKIP}" = true ] && [ -f "${dockerfile}" ]; then
+      existing_yarn_version=$(grep -m1 'ENV YARN_VERSION=' "${dockerfile}" | cut -d'=' -f2 || echo "")
+      if [ -n "${existing_yarn_version}" ]; then
+        sed -Ei -e 's/^(ENV YARN_VERSION)=.*/\1='"${existing_yarn_version}"'/' "${dockerfile}-tmp"
+      fi
+    fi
 
     sed -Ei -e 's/^FROM (.*)/FROM '"$fromprefix"'\1/' "${dockerfile}-tmp"
     sed -Ei -e 's/^(ENV NODE_VERSION)=.*/\1='"${nodeVersion}"'/' "${dockerfile}-tmp"
@@ -208,6 +216,11 @@ for version in "${versions[@]}"; do
     # Skip non-docker directories
     [ -f "${version}/${variant}/Dockerfile" ] || continue
 
+    # Skip alpine variants when SKIP is true
+    if [ "${SKIP}" = true ] && is_alpine "${variant}"; then
+      continue
+    fi
+
     update_variant=$(in_variants_to_update "${variant}")
     template_file="${parentpath}/Dockerfile-${variant}.template"