Avoid a StackOverflow and properly fail on cyclic references in CRD generation

crd-generator/api/src/main/java/io/fabric8/crd/generator/AbstractJsonSchema.java

@@ -29,19 +29,14 @@
 
 import java.util.*;
 
-import static io.sundr.model.utils.Types.BOOLEAN;
 import static io.sundr.model.utils.Types.BOOLEAN_REF;
 
-import static io.sundr.model.utils.Types.STRING;
 import static io.sundr.model.utils.Types.STRING_REF;
 
-import static io.sundr.model.utils.Types.INT;
 import static io.sundr.model.utils.Types.INT_REF;
 
-import static io.sundr.model.utils.Types.LONG;
 import static io.sundr.model.utils.Types.LONG_REF;
 
-import static io.sundr.model.utils.Types.DOUBLE;
 import static io.sundr.model.utils.Types.DOUBLE_REF;
 
 /**
@@ -117,6 +112,10 @@ public static String getSchemaTypeFor(TypeRef typeRef) {
    * @return The schema.
    */
   protected T internalFrom(TypeDef definition, String... ignore) {
+    return internalFromImpl(definition, new HashSet<>(), ignore);
+  }
+
+  private T internalFromImpl(TypeDef definition, Set<String> visited, String... ignore) {
     final B builder = newBuilder();
     Set<String> ignores =
       ignore.length > 0 ? new LinkedHashSet<>(Arrays.asList(ignore)) : Collections
@@ -140,7 +139,7 @@ protected T internalFrom(TypeDef definition, String... ignore) {
       if (facade.required) {
         required.add(name);
       }
-      final T schema = internalFrom(name, possiblyRenamedProperty.getTypeRef());
+      final T schema = internalFromImpl(name, possiblyRenamedProperty.getTypeRef(), visited);
       // if we got a description from the field or an accessor, use it
       final String description = facade.description;
       final T possiblyUpdatedSchema;
@@ -361,12 +360,16 @@ private String extractUpdatedNameFromJacksonPropertyIfPresent(Property property)
    * @return the structural schema associated with the specified property
    */
   public T internalFrom(String name, TypeRef typeRef) {
+    return internalFromImpl(name, typeRef, new HashSet<>());
+  }
+
+  private T internalFromImpl(String name, TypeRef typeRef, Set<String> visited) {
     // Note that ordering of the checks here is meaningful: we need to check for complex types last
     // in case some "complex" types are handled specifically
     if (typeRef.getDimensions() > 0 || io.sundr.model.utils.Collections.isCollection(typeRef)) { // Handle Collections & Arrays
       final TypeRef collectionType = TypeAs.combine(TypeAs.UNWRAP_ARRAY_OF, TypeAs.UNWRAP_COLLECTION_OF)
         .apply(typeRef);
-      final T schema = internalFrom(name, collectionType);
+      final T schema = internalFromImpl(name, collectionType, visited);
       return arrayLikeProperty(schema);
     } else if (io.sundr.model.utils.Collections.IS_MAP.apply(typeRef)) { // Handle Maps
       final TypeRef keyType = TypeAs.UNWRAP_MAP_KEY_OF.apply(typeRef);
@@ -390,7 +393,7 @@ public T internalFrom(String name, TypeRef typeRef) {
       }
       return mapLikeProperty();
     } else if (io.sundr.model.utils.Optionals.isOptional(typeRef)) { // Handle Optionals
-      return internalFrom(name, TypeAs.UNWRAP_OPTIONAL_OF.apply(typeRef));
+      return internalFromImpl(name, TypeAs.UNWRAP_OPTIONAL_OF.apply(typeRef), visited);
     } else {
       final String typeName = COMMON_MAPPINGS.get(typeRef);
       if (typeName != null) { // we have a type that we handle specifically
@@ -413,7 +416,7 @@ public T internalFrom(String name, TypeRef typeRef) {
               .toArray(JsonNode[]::new);
             return enumProperty(enumValues);
           } else {
-            return internalFrom(def);
+            return resolveNestedClass(name, def, visited);
           }
 
         }
@@ -422,6 +425,26 @@ public T internalFrom(String name, TypeRef typeRef) {
     }
   }
 
+  // Flag to detect cycles
+  private boolean resolving = false;
+
+  private T resolveNestedClass(String name, TypeDef def, Set<String> visited) {
+    if (!resolving) {
+      visited.clear();
+      resolving = true;
+    } else {
+      String visitedName = name + ":" + def.getFullyQualifiedName();
+      if (!def.getFullyQualifiedName().startsWith("java") && visited.contains(visitedName)) {
+        throw new IllegalArgumentException("Found a cyclic reference involving the field " + name + " of type " + def.getFullyQualifiedName());
+      }
+      visited.add(visitedName);
+    }
+
+    T res = internalFromImpl(def, visited);
+    resolving = false;
+    return res;
+  }
+
   /**
    * Builds the schema for specifically handled property types (e.g. intOrString properties)
    *

crd-generator/api/src/test/java/io/fabric8/crd/example/cyclic/Cyclic.java

@@ -0,0 +1,27 @@
+/**
+ * Copyright (C) 2015 Red Hat, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *         http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.fabric8.crd.example.cyclic;
+
+import io.fabric8.kubernetes.api.model.Namespaced;
+import io.fabric8.kubernetes.client.CustomResource;
+import io.fabric8.kubernetes.model.annotation.Group;
+import io.fabric8.kubernetes.model.annotation.Version;
+
+@Group("sample.fabric8.io")
+@Version("v1alpha1")
+public class Cyclic extends CustomResource<CyclicSpec, CyclicStatus> implements Namespaced {
+
+}

crd-generator/api/src/test/java/io/fabric8/crd/example/cyclic/CyclicSpec.java

@@ -0,0 +1,20 @@
+/**
+ * Copyright (C) 2015 Red Hat, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *         http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.fabric8.crd.example.cyclic;
+
+public class CyclicSpec {
+  private Ref ref;
+}

crd-generator/api/src/test/java/io/fabric8/crd/example/cyclic/CyclicStatus.java

@@ -0,0 +1,20 @@
+/**
+ * Copyright (C) 2015 Red Hat, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *         http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.fabric8.crd.example.cyclic;
+
+public class CyclicStatus {
+  private String message;
+}

crd-generator/api/src/test/java/io/fabric8/crd/example/cyclic/Ref.java

@@ -0,0 +1,22 @@
+/**
+ * Copyright (C) 2015 Red Hat, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *         http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.fabric8.crd.example.cyclic;
+
+public class Ref {
+
+  private Ref ref;
+
+}

crd-generator/api/src/test/java/io/fabric8/crd/example/nocyclic/NoCyclic.java

@@ -0,0 +1,27 @@
+/**
+ * Copyright (C) 2015 Red Hat, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *         http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.fabric8.crd.example.nocyclic;
+
+import io.fabric8.kubernetes.api.model.Namespaced;
+import io.fabric8.kubernetes.client.CustomResource;
+import io.fabric8.kubernetes.model.annotation.Group;
+import io.fabric8.kubernetes.model.annotation.Version;
+
+@Group("sample.fabric8.io")
+@Version("v1alpha1")
+public class NoCyclic extends CustomResource<NoCyclicSpec, NoCyclicStatus> implements Namespaced {
+
+}

crd-generator/api/src/test/java/io/fabric8/crd/example/nocyclic/NoCyclicSpec.java

@@ -0,0 +1,21 @@
+/**
+ * Copyright (C) 2015 Red Hat, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *         http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.fabric8.crd.example.nocyclic;
+
+public class NoCyclicSpec {
+  private Ref ref1;
+  private Ref ref2;
+}

crd-generator/api/src/test/java/io/fabric8/crd/example/nocyclic/NoCyclicStatus.java

@@ -0,0 +1,21 @@
+/**
+ * Copyright (C) 2015 Red Hat, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *         http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.fabric8.crd.example.nocyclic;
+
+public class NoCyclicStatus {
+  private String message;
+  private Ref ref1;
+}

crd-generator/api/src/test/java/io/fabric8/crd/example/nocyclic/Ref.java

@@ -0,0 +1,26 @@
+/**
+ * Copyright (C) 2015 Red Hat, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *         http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.fabric8.crd.example.nocyclic;
+
+public class Ref {
+
+  private int ref;
+
+  protected Inner inner;
+
+  public static class Inner { }
+
+}

crd-generator/api/src/test/java/io/fabric8/crd/generator/CRDGeneratorTest.java

@@ -18,13 +18,15 @@
 import io.fabric8.crd.example.basic.Basic;
 import io.fabric8.crd.example.basic.BasicSpec;
 import io.fabric8.crd.example.basic.BasicStatus;
+import io.fabric8.crd.example.cyclic.Cyclic;
 import io.fabric8.crd.example.inherited.*;
 import io.fabric8.crd.example.joke.Joke;
 import io.fabric8.crd.example.joke.JokeRequest;
 import io.fabric8.crd.example.joke.JokeRequestSpec;
 import io.fabric8.crd.example.joke.JokeRequestStatus;
 import io.fabric8.crd.example.multiple.v1.Multiple;
 import io.fabric8.crd.example.multiple.v1.MultipleSpec;
+import io.fabric8.crd.example.nocyclic.NoCyclic;
 import io.fabric8.crd.example.simplest.Simplest;
 import io.fabric8.crd.example.simplest.SimplestSpec;
 import io.fabric8.crd.example.simplest.SimplestStatus;
@@ -197,6 +199,28 @@ void shouldProperlyGenerateMultipleVersionsOfCRDs() {
     assertEquals(0, generator.generate());
   }
 
+  @Test void generatingACycleShouldFail() {
+    final CRDGenerator generator = new CRDGenerator()
+      .customResourceClasses(Cyclic.class)
+      .forCRDVersions("v1", "v1beta1")
+      .withOutput(output);
+
+    assertThrows(
+      IllegalArgumentException.class,
+      () -> generator.detailedGenerate(),
+      "An IllegalArgument Exception hasn't been thrown when generating a CRD with cyclic references"
+    );
+  }
+
+  @Test void notGeneratingACycleShouldSucceed() {
+    final CRDGenerator generator = new CRDGenerator()
+      .customResourceClasses(NoCyclic.class)
+      .forCRDVersions("v1", "v1beta1")
+      .withOutput(output);
+
+    CRDGenerationInfo info = generator.detailedGenerate();
+    assertEquals(2, info.numberOfGeneratedCRDs());
+  }
 
   @FunctionalInterface
   private interface CRTest {