EnableContextRegion.java

/*
 * Copyright 2013-2014 the original author or 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
 *
 *      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 org.springframework.cloud.aws.context.config.annotation;

import org.springframework.context.annotation.Import;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * Configures a {@link org.springframework.cloud.aws.core.region.RegionProvider} instance for the application context. The
 * region provider will be used for all Amazon Web Service clients that are created inside the application context (by
 * the Spring Cloud AWS classes). A region can be either manually configured {@link EnableContextRegion#region()} with
 * a constant expression, dynamic expression (using a SpEL expression) or a place holder. The region can also be dynamically
 * retrieved from the EC2 instance meta-data if the application context is running inside a EC2 instance by enabling the
 * {@link EnableContextRegion#autoDetect()} attribute.
 *
 * @author Agim Emruli
 */
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
@Import(ContextRegionConfigurationRegistrar.class)
public @interface EnableContextRegion {

    /**
     * Configures the region as a String value. The value must match to an enum defined in
     * {@link com.amazonaws.regions.Regions}. This attribute is a String value allowing expressions and placeholders to
     * be used for the region configuration.
     *
     * @return - the region a constant definition, SpEL expression or placeholder definition
     */
    String region() default "";

    /**
     * Configures the auto-detection of a region that should be fetched from the EC2 meta-data. Disabled by default.
     *
     * @return - configures if the region should be fetched by the EC2 meta-data. Must be false if a region is configured
     * in the {@link EnableContextRegion#region()} attribute.
     */
    boolean autoDetect() default false;
}