Add oneOfStrings validator annotation for configuration validation

core/src/main/java/feast/core/config/FeastProperties.java

@@ -17,10 +17,10 @@
 package feast.core.config;
 
 import feast.core.config.FeastProperties.StreamProperties.FeatureStreamOptions;
+import feast.core.validators.OneOfStrings;
 import java.util.*;
 import javax.annotation.PostConstruct;
 import javax.validation.*;
-import javax.validation.constraints.AssertTrue;
 import javax.validation.constraints.NotBlank;
 import javax.validation.constraints.NotNull;
 import javax.validation.constraints.Positive;
@@ -130,7 +130,9 @@ public feast.core.job.Runner getType() {
   public static class StreamProperties {
 
     /* Feature stream type. Only "kafka" is supported. */
-    @NotBlank private String type;
+    @OneOfStrings({"kafka"})
+    @NotBlank
+    private String type;
 
     /* Feature stream options */
     @NotNull private FeatureStreamOptions options;
@@ -157,16 +159,6 @@ public static class FeatureStreamOptions {
     }
   }
 
-  /**
-   * Validates whether stream options are correct.
-   *
-   * @return Boolean used for assertion
-   */
-  @AssertTrue
-  public boolean isValidStreamTypeSelected() {
-    return Objects.equals(getStream().getType(), "kafka");
-  }
-
   /** Feast population job metrics */
   @Getter
   @Setter
@@ -176,7 +168,9 @@ public static class MetricsProperties {
     private boolean enabled;
 
     /* Metric type. Possible options: statsd */
-    @NotBlank private String type;
+    @OneOfStrings({"statsd"})
+    @NotBlank
+    private String type;
 
     /* Host of metric sink */
     @URL private String host;

core/src/main/java/feast/core/validators/OneOfStringValidator.java

@@ -0,0 +1,51 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ * Copyright 2018-2020 The Feast Authors
+ *
+ * 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
+ *
+ *     https://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 feast.core.validators;
+
+import java.util.Arrays;
+import javax.validation.ConstraintValidator;
+import javax.validation.ConstraintValidatorContext;
+
+/** Validates whether a string value is found within a collection. */
+public class OneOfStringValidator implements ConstraintValidator<OneOfStrings, String> {
+
+  /** Values that are permitted for a specific instance of this validator */
+  String[] allowedValues;
+
+  /**
+   * Initialize the OneOfStringValidator with a collection of allowed String values.
+   *
+   * @param constraintAnnotation
+   */
+  @Override
+  public void initialize(OneOfStrings constraintAnnotation) {
+    allowedValues = constraintAnnotation.value();
+  }
+
+  /**
+   * Validates whether a string value is found within the collection defined in the annotation.
+   *
+   * @param value String value that should be validated
+   * @param context Provides contextual data and operation when applying a given constraint
+   *     validator
+   * @return Boolean value indicating whether the string is found within the allowed values.
+   */
+  @Override
+  public boolean isValid(String value, ConstraintValidatorContext context) {
+    return Arrays.asList(allowedValues).contains(value);
+  }
+}

core/src/main/java/feast/core/validators/OneOfStrings.java

@@ -0,0 +1,49 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ * Copyright 2018-2020 The Feast Authors
+ *
+ * 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
+ *
+ *     https://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 feast.core.validators;
+
+import java.lang.annotation.*;
+import javax.validation.Constraint;
+import javax.validation.Payload;
+
+/**
+ * Annotation for String "one of" validation. Allows for the definition of a collection through an
+ * annotation. The collection is used to test values defined in the object.
+ */
+@Target({
+  ElementType.METHOD,
+  ElementType.FIELD,
+  ElementType.ANNOTATION_TYPE,
+  ElementType.CONSTRUCTOR,
+  ElementType.PARAMETER
+})
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+@Constraint(validatedBy = OneOfStringValidator.class)
+public @interface OneOfStrings {
+  /** @return Default error message that is returned if the incorrect value is set */
+  String message() default "Field value must be one of the following: {value}";
+
+  /** Allows for the specification of validation groups to which this constraint belongs. */
+  Class<?>[] groups() default {};
+
+  /** An attribute payload that can be used to assign custom payload objects to a constraint. */
+  Class<? extends Payload>[] payload() default {};
+
+  /** @return Default value that is returned if no allowed values are configured */
+  String[] value() default {};
+}