tracking missing cachingRelevantProperties for configuration cache

Author: cdsap

devtools/gradle/gradle-application-plugin/src/main/java/io/quarkus/gradle/tasks/BaseConfig.java

@@ -58,11 +58,22 @@ Manifest manifest() {
     Map<String, String> cachingRelevantProperties(List<String> propertyPatterns) {
         List<Pattern> patterns = propertyPatterns.stream().map(s -> "^(" + s + ")$").map(Pattern::compile)
                 .collect(Collectors.toList());
+        readMissingEnvVariables(propertyPatterns);
         Predicate<Map.Entry<String, ?>> keyPredicate = e -> patterns.stream().anyMatch(p -> p.matcher(e.getKey()).matches());
         return values.entrySet().stream()
                 .filter(keyPredicate)
                 .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue, (s, s2) -> {
                     throw new IllegalArgumentException("Duplicate key");
                 }, TreeMap::new));
     }
+
+    /**
+     * Reads missing environment variables that have been defined as `cachingRelevantProperties`.
+     * This ensures that the configuration cache tracks these variables as inputs and detects changes in them.
+     */
+    private void readMissingEnvVariables(List<String> cachingRelevantProperties) {
+        cachingRelevantProperties.stream()
+                .filter(name -> !values.containsKey(name))
+                .forEach(name -> System.getenv(name));
+    }
 }

devtools/gradle/gradle-application-plugin/src/test/java/io/quarkus/gradle/tasks/CachingTest.java

@@ -81,7 +81,7 @@ void envChangeInvalidatesBuild() throws Exception {
                 "-Dquarkus.randomized.value=" + UUID.randomUUID())
                 .toArray(new String[0]);
 
-        Map<String, String> env = Map.of("FOO_ENV_VAR", "initial-value");
+        Map<String, String> env = Map.of();
         assertBuildResult("initial", gradleBuild(rerunTasks(arguments), env), ALL_SUCCESS);
         assertBuildResult("initial rebuild", gradleBuild(arguments, env), ALL_UP_TO_DATE);