Fix config sources ordering

consul/runtime/src/main/java/io/quarkus/consul/config/runtime/ConsulConfigSourceFactory.java

@@ -45,22 +45,25 @@ Iterable<ConfigSource> getConfigSources(ConsulConfig config, ConsulConfigGateway
             return Collections.emptyList();
         }
 
-        List<ConfigSource> result = new ArrayList<>(keys.size());
+        Map<String, ConfigSource> results = new LinkedHashMap<>(keys.size());
 
         List<Uni<?>> allUnis = new ArrayList<>();
 
         for (Map.Entry<String, ValueType> entry : keys.entrySet()) {
             String fullKey = config.prefix().isPresent() ? config.prefix().get() + "/" + entry.getKey() : entry.getKey();
+            results.put(fullKey, null);
             allUnis.add(consulConfigGateway.getValue(fullKey).invoke(new Consumer<Response>() {
                 @Override
                 public void accept(Response response) {
                     if (response != null) {
-                        result.add(ResponseConfigSourceUtil.toConfigSource(response, entry.getValue(), config.prefix()));
+                        results.put(response.getKey(),
+                                ResponseConfigSourceUtil.toConfigSource(response, entry.getValue(), config.prefix()));
                     } else {
                         String message = "Key '" + fullKey + "' not found in Consul.";
                         if (config.failOnMissingKey()) {
                             throw new RuntimeException(message);
                         } else {
+                            results.remove(fullKey);
                             log.info(message);
                         }
                     }
@@ -81,6 +84,6 @@ public void accept(Response response) {
             consulConfigGateway.close();
         }
 
-        return result;
+        return results.values();
     }
 }

consul/runtime/src/test/java/io/quarkus/consul/config/runtime/ConsulConfigSourceFactoryTest.java

@@ -14,6 +14,7 @@
 
 import java.util.Arrays;
 import java.util.List;
+import java.util.Map;
 import java.util.Optional;
 
 import org.eclipse.microprofile.config.spi.ConfigSource;
@@ -207,6 +208,35 @@ void testPropertiesKeysWithPrefix() {
         verify(mockGateway, times(1)).getValue("config/second");
     }
 
+    @Test
+    void testConfigSourcesOrdered() {
+        ConsulConfig config = mock(ConsulConfig.class);
+        // We want this order: first > second > third (first overrides second which overrides third)
+        when(config.rawValueKeys()).thenReturn(keyValues("some/first", "some/second", "some/third"));
+        AgentConfig agentConfig = mock(AgentConfig.class);
+        when(config.agent()).thenReturn(agentConfig);
+
+        ConsulConfigGateway mockGateway = mock(ConsulConfigGateway.class);
+        // make sure the third property is received first
+        when(mockGateway.getValue("some/first")).thenReturn(validResponse("some/third", "third"));
+        // make sure the first property is received in second
+        when(mockGateway.getValue("some/second")).thenReturn(validResponse("some/first", "first"));
+        // make sure the second property is received in third
+        when(mockGateway.getValue("some/third")).thenReturn(validResponse("some/second", "second"));
+
+        Iterable<ConfigSource> configSources = new ConsulConfigSourceFactory().getConfigSources(config, mockGateway);
+        assertThat(configSources).hasSize(3);
+        assertThat(configSources).extracting(ConfigSource::getProperties).containsExactly(
+                Map.of("some.first", "first"),
+                Map.of("some.second", "second"),
+                Map.of("some.third", "third"));
+
+        //all keys should have been resolved because we resolve keys in the order they were given by the user
+        verify(mockGateway, times(1)).getValue("some/first");
+        verify(mockGateway, times(1)).getValue("some/second");
+        verify(mockGateway, times(1)).getValue("some/third");
+    }
+
     private Optional<List<String>> keyValues(String... keys) {
         return Optional.of(Arrays.asList(keys));
     }