Fallback specialized kubernetes config to vanilla kubernetes

extensions/kubernetes/openshift/deployment/pom.xml

@@ -49,6 +49,10 @@
             <artifactId>quarkus-junit5-internal</artifactId>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>io.smallrye.config</groupId>
+            <artifactId>smallrye-config-source-yaml</artifactId>
+        </dependency>
     </dependencies>
 
     <build>

extensions/kubernetes/openshift/deployment/src/test/java/io/quarkus/openshift/deployment/config/OpenshiftConfigFallbackTest.java

@@ -0,0 +1,47 @@
+package io.quarkus.openshift.deployment.config;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+
+import java.nio.file.Path;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.RegisterExtension;
+
+import io.quarkus.test.ProdBuildResults;
+import io.quarkus.test.ProdModeTestResults;
+import io.quarkus.test.QuarkusProdModeTest;
+import io.smallrye.config.source.yaml.YamlConfigSource;
+
+public class OpenshiftConfigFallbackTest {
+    @RegisterExtension
+    static final QuarkusProdModeTest TEST = new QuarkusProdModeTest()
+            .setApplicationName("config")
+            .setApplicationVersion("0.1-SNAPSHOT")
+            .overrideConfigKey("quarkus.kubernetes.replicas", "10")
+            .overrideConfigKey("quarkus.openshift.version", "999-SNAPSHOT")
+            .overrideConfigKey("quarkus.openshift.labels.app", "openshift")
+            .setRun(true);
+
+    @ProdBuildResults
+    private ProdModeTestResults prodModeTestResults;
+
+    @Test
+    void configFallback() throws Exception {
+        Path kubernetesDir = prodModeTestResults.getBuildDir().resolve("kubernetes");
+        YamlConfigSource kubernetes = new YamlConfigSource(kubernetesDir.resolve("kubernetes.yml").toUri().toURL());
+        YamlConfigSource openshift = new YamlConfigSource(kubernetesDir.resolve("openshift.yml").toUri().toURL());
+
+        // Only in Kubernetes, must fallback to Openshift
+        assertEquals("10", kubernetes.getValue("spec.replicas"));
+        assertEquals("10", openshift.getValue("spec.replicas"));
+
+        // In both, each should retain the value
+        assertEquals("0.1-SNAPSHOT", kubernetes.getValue("spec.template.metadata.labels.\"app.kubernetes.io/version\""));
+        assertEquals("999-SNAPSHOT", openshift.getValue("spec.template.metadata.labels.\"app.kubernetes.io/version\""));
+
+        // Only in Openshift
+        assertNull(kubernetes.getValue("spec.template.metadata.labels.app"));
+        assertEquals("openshift", openshift.getValue("spec.template.metadata.labels.app"));
+    }
+}

extensions/kubernetes/vanilla/runtime/src/main/java/io/quarkus/kubernetes/runtime/config/KubernetesConfigFallback.java

@@ -0,0 +1,23 @@
+package io.quarkus.kubernetes.runtime.config;
+
+import java.util.function.Function;
+
+import io.smallrye.config.FallbackConfigSourceInterceptor;
+
+public class KubernetesConfigFallback extends FallbackConfigSourceInterceptor {
+    public KubernetesConfigFallback() {
+        super(new Function<String, String>() {
+            @Override
+            public String apply(final String name) {
+                if (name.startsWith("quarkus.openshift.")) {
+                    return "quarkus.kubernetes." + name.substring(18);
+                } else if (name.startsWith("quarkus.knative.")) {
+                    return "quarkus.kubernetes." + name.substring(16);
+                } else if (name.startsWith("quarkus.minikube.")) {
+                    return "quarkus.kubernetes." + name.substring(17);
+                }
+                return name;
+            }
+        });
+    }
+}

extensions/kubernetes/vanilla/runtime/src/main/resources/META-INF/services/io.smallrye.config.ConfigSourceInterceptor

@@ -0,0 +1 @@
+io.quarkus.kubernetes.runtime.config.KubernetesConfigFallback