Optimized runtime variables script + improved maintainability and POSIX compliance

Signed-off-by: Tim Schlagenhaufer <tim.schlagenhaufer@bosch.io>

Author: schlagtim

frontend/setup-runtime.sh

@@ -5,15 +5,30 @@
 #
 # SPDX-License-Identifier: Apache-2.0
 
+# Keep this shell script POSIX compliant
 # First argument: Path to env.js which needs to be modified
 # Second argument: Path to BPA jar file to replace env.js
 echo "Start setting runtime variables"
 
-# Overwrite frontend runtime variables with environment variables from container
-sed -i 's#__SIDEBAR_CLOSE_ON_STARTUP__#'"$SIDEBAR_CLOSE_ON_STARTUP"'#g' "$1"
-sed -i 's#__SIDEBAR_HIDE_BURGER_BUTTON__#'"$SIDEBAR_HIDE_BURGER_BUTTON"'#g' "$1"
+# Add new runtime variable names in this string delimited by a space character ' '
+definedVariables="SIDEBAR_CLOSE_ON_STARTUP SIDEBAR_HIDE_BURGER_BUTTON"
+modifiedVariablesCounter=0
 
-# Overwrite env.js in given jar file (path)
-jar uf "$2" "$1"
+for item in $definedVariables ; do # Do not use double-quotes for $definedVariables
+  eval envvar=\"\$"$item"\"
+  if [ -n "$envvar" ]; then
+    echo "Runtime variable $item is set to '$envvar'"
+
+    # Overwrite frontend runtime variables in env.js with environment variables from container
+    sed -i "s#__${item}__#""$envvar"'#g' "$1"
+    modifiedVariablesCounter=$((modifiedVariablesCounter+1))
+  fi
+done
+
+# Overwrite env.js file in given jar file (path) if at least one runtime variable is set
+if [ "$modifiedVariablesCounter" -gt 0 ]; then
+  echo "Updating env.js file in jar"
+  jar uf "$2" "$1"
+fi
 
 echo "Finish setting runtime variables"