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new c9c55f306 Fix order-dependent resolution of cross-referencing
properties (#437)
c9c55f306 is described below
commit c9c55f30608b5204f2c285db80b4b144d2ed1090
Author: Piotr P. Karwasz <[email protected]>
AuthorDate: Fri May 29 22:54:16 2026 +0200
Fix order-dependent resolution of cross-referencing properties (#437)
When properties are defined in terms of each other, e.g. `a = ${b}` with `b
= OK`, `MapResolver#resolveProperties` filled the result map while using that
same map as the lookup source, so a reference only resolved when the referenced
property had already been evaluated. As the iteration order of
`Properties#stringPropertyNames` is unspecified, properties like `a` were
sometimes left unresolved.
Pre-seed the map with the raw values so that every key is visible to the
lookup regardless of evaluation order.
`TestMapResolver` covers both reference orderings, and documents that
self-referencing and cyclic definitions are left to Commons Text's recursion
guard, which either returns the literal or throws `IllegalStateException`.
---
.../java/org/apache/flume/node/MapResolver.java | 4 +++
.../org/apache/flume/node/TestMapResolver.java | 40 ++++++++++++++++++++++
2 files changed, 44 insertions(+)
diff --git a/flume-ng-node/src/main/java/org/apache/flume/node/MapResolver.java
b/flume-ng-node/src/main/java/org/apache/flume/node/MapResolver.java
index ea933ec0d..2af9bfc67 100644
--- a/flume-ng-node/src/main/java/org/apache/flume/node/MapResolver.java
+++ b/flume-ng-node/src/main/java/org/apache/flume/node/MapResolver.java
@@ -56,6 +56,9 @@ final class MapResolver {
public static Map<String, String> resolveProperties(Properties properties) {
Map<String, String> map = new HashMap<>();
+ // Pre-seed the map, so that evaluation doesn't depend on the order of
Properties#stringPropertyNames
+ properties.forEach((key, value) -> map.put(key.toString(),
value.toString()));
+
boolean useEnvVars =
ENV_VAR_PROPERTY.equals(System.getProperty(PROPS_IMPL_KEY));
StringLookup defaultLookup = useEnvVars ? new DefaultLookup(map) :
StringLookupFactory.INSTANCE.mapStringLookup(map);
@@ -63,6 +66,7 @@ final class MapResolver {
defaultLookup, false);
StringSubstitutor substitutor = new StringSubstitutor(lookup);
substitutor.setEnableSubstitutionInVariables(true);
+
properties.stringPropertyNames().forEach((k) -> map.put(k,
substitutor.replace(properties.getProperty(k))));
return map;
diff --git
a/flume-ng-node/src/test/java/org/apache/flume/node/TestMapResolver.java
b/flume-ng-node/src/test/java/org/apache/flume/node/TestMapResolver.java
index 9ba57ed8d..b8b9d753b 100644
--- a/flume-ng-node/src/test/java/org/apache/flume/node/TestMapResolver.java
+++ b/flume-ng-node/src/test/java/org/apache/flume/node/TestMapResolver.java
@@ -80,4 +80,44 @@ public class TestMapResolver {
assertEquals("Test lookup was not resolved", "Value", test);
}
+ @Test
+ public void testOrderOfEvaluation() {
+ // Tests that the evaluation order does not depend
+ // on the order of Properties#propertyNames
+ Properties properties = new Properties();
+ properties.setProperty("a", "${b}");
+ properties.setProperty("b", "OK");
+ Map<String, String> resolveProperties =
MapResolver.resolveProperties(properties);
+ assertEquals("Incorrect order of evaluation", "OK",
resolveProperties.get("a"));
+
+ properties = new Properties();
+ properties.setProperty("b", "${a}");
+ properties.setProperty("a", "OK");
+ resolveProperties = MapResolver.resolveProperties(properties);
+ assertEquals("Incorrect order of evaluation", "OK",
resolveProperties.get("b"));
+ }
+
+ @Test
+ public void testDoesNotResolveRecursiveLookup() {
+ // Commons Text has a self-recursion guard
+ Properties props = new Properties();
+ props.setProperty("a", "${a}");
+ try {
+ // If it does throw, it should return the definition
+ assertEquals("${a}", MapResolver.resolveProperties(props).get("a"));
+ } catch (IllegalStateException ignored) {
+ // or it can throw
+ }
+
+ props = new Properties();
+ props.setProperty("a", "${b}");
+ props.setProperty("b", "${a}");
+ try {
+ // If it does throw, it should return the definition
+ assertEquals("${b}", MapResolver.resolveProperties(props).get("a"));
+ } catch (IllegalStateException ignored) {
+ // or it can throw
+ }
+ }
+
}
