EC2MetadataUtils 的替代品

Question

在我们的代码中，为了获取我们正在使用的 ec2 实例的区域EC2MetadataUtils.getEC2InstanceRegion()，我们刚刚意识到我们不能使用它EC2MetadataUtils，因为它是一个内部 API，可能会发生变化。

注意：这是一个内部 API，可能会发生变化。SDK 用户不应依赖于此。

进行了一些谷歌搜索，但无法找到替代解决方案，是否有任何替代解决方案可用于获取 ec2 实例的区域？

谢谢你的帮助！

Answer 1

这是以下的实现class： https: //github.com/aws/aws-sdk-java/blob/master/aws-java-sdk-core/src/main/java/com/amazonaws/util/EC2MetadataUtils.java

尽管在谷歌上进行了搜索，但我没有找到 Java 替代方案，因此，我意识到需要进行更深入的研究。我将您拥有的可能性描述如下：

1. 你可以保持原样

该警告清楚地表明使用替代方案是一个好主意，但不存在现成的替代方案以及未来版本的可能优点是class很好的反驳，因此您现在可以忽略此注释。

2.可以下载开源库并搜索该方法的调用

如果您在库中的其他地方找到了对此方法的调用，并且您能够以某种方式使用它，那么这可能是一种替代方案。例如，克隆后

git clone git@github.com:aws/aws-sdk-java.git

并使用以下命令搜索此方法的出现：

grep -rn 'yourpath' -e "getEC2InstanceRegion"

我得到了这些结果：

<path>/aws-sdk-java/aws-java-sdk-core/src/main/java/com/amazonaws/util/EC2MetadataUtils.java:286:    public static String getEC2InstanceRegion() {
<path>/aws-sdk-java/aws-java-sdk-core/src/main/java/com/amazonaws/regions/InstanceMetadataRegionProvider.java:59:            return EC2MetadataUtils.getEC2InstanceRegion();
<path>/aws-sdk-java/aws-java-sdk-core/src/main/java/com/amazonaws/regions/Regions.java:110:            final String region = EC2MetadataUtils.getEC2InstanceRegion();

第一个匹配是方法的定义。

第二场比赛如下所示：

/*
 * Copyright 2011-2022 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License").
 * You may not use this file except in compliance with the License.
 * A copy of the License is located at
 *
 *  http://aws.amazon.com/apache2.0
 *
 * or in the "license" file accompanying this file. This file 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 com.amazonaws.regions;

import com.amazonaws.AmazonClientException;
import com.amazonaws.SDKGlobalConfiguration;
import com.amazonaws.util.EC2MetadataUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * Attempts to load region information from the EC2 Metadata service. If the application is not
 * running on EC2 or {@link SDKGlobalConfiguration#isEc2MetadataDisabled()} returns true,
 * this provider will return null.
 */
public class InstanceMetadataRegionProvider extends AwsRegionProvider {

    private static final Log LOG = LogFactory.getLog(InstanceMetadataRegionProvider.class);

    /**
     * Cache region as it will not change during the lifetime of the JVM.
     */
    private volatile String region;

    /**
     * @throws AmazonClientException if {@link SDKGlobalConfiguration#isEc2MetadataDisabled()} is true
     */
    @Override
    public String getRegion() {
        if (SDKGlobalConfiguration.isEc2MetadataDisabled()) {
            throw new AmazonClientException("AWS_EC2_METADATA_DISABLED is set to true, not loading region from EC2 Instance "
                                         + "Metadata service");
        }

        if (region == null) {
            synchronized (this) {
                if (region == null) {
                    this.region = tryDetectRegion();
                }
            }
        }
        return region;
    }

    private String tryDetectRegion() {
        try {
            return EC2MetadataUtils.getEC2InstanceRegion();
        } catch (AmazonClientException sce) {
            LOG.debug("Ignoring failure to retrieve the region: " + sce.getMessage());
            return null;
        }
    }
}

因此，看起来getRegion的方法InstanceMetadataRegionProvider看起来像是您正在寻找的替代方案。

第三场比赛如下所示：

/*
 * Copyright 2013-2022 Amazon Technologies, 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://aws.amazon.com/apache2.0
 *
 * This file 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 com.amazonaws.regions;

import com.amazonaws.AmazonClientException;
import org.apache.commons.logging.LogFactory;

import com.amazonaws.util.EC2MetadataUtils;

/**
 * Enumeration of region names
 */
public enum Regions {

    GovCloud("us-gov-west-1", "AWS GovCloud (US)"),
    US_GOV_EAST_1("us-gov-east-1", "AWS GovCloud (US-East)"),
    US_EAST_1("us-east-1", "US East (N. Virginia)"),
    US_EAST_2("us-east-2", "US East (Ohio)"),
    US_WEST_1("us-west-1", "US West (N. California)"),
    US_WEST_2("us-west-2", "US West (Oregon)"),
    EU_WEST_1("eu-west-1", "EU (Ireland)"),
    EU_WEST_2("eu-west-2", "EU (London)"),
    EU_WEST_3("eu-west-3", "EU (Paris)"),
    EU_CENTRAL_1("eu-central-1", "EU (Frankfurt)"),
    EU_NORTH_1("eu-north-1", "EU (Stockholm)"),
    EU_SOUTH_1("eu-south-1", "EU (Milan)"),
    AP_EAST_1("ap-east-1", "Asia Pacific (Hong Kong)"),
    AP_SOUTH_1("ap-south-1", "Asia Pacific (Mumbai)"),
    AP_SOUTHEAST_1("ap-southeast-1", "Asia Pacific (Singapore)"),
    AP_SOUTHEAST_2("ap-southeast-2", "Asia Pacific (Sydney)"),
    AP_SOUTHEAST_3("ap-southeast-3", "Asia Pacific (Jakarta)"),
    AP_NORTHEAST_1("ap-northeast-1", "Asia Pacific (Tokyo)"),
    AP_NORTHEAST_2("ap-northeast-2", "Asia Pacific (Seoul)"),
    AP_NORTHEAST_3("ap-northeast-3", "Asia Pacific (Osaka)"),

    SA_EAST_1("sa-east-1", "South America (Sao Paulo)"),
    CN_NORTH_1("cn-north-1", "China (Beijing)"),
    CN_NORTHWEST_1("cn-northwest-1", "China (Ningxia)"),
    CA_CENTRAL_1("ca-central-1", "Canada (Central)"),
    ME_SOUTH_1("me-south-1", "Middle East (Bahrain)"),
    AF_SOUTH_1("af-south-1", "Africa (Cape Town)"),
    US_ISO_EAST_1("us-iso-east-1", "US ISO East"),
    US_ISOB_EAST_1("us-isob-east-1", "US ISOB East (Ohio)"),
    US_ISO_WEST_1("us-iso-west-1", "US ISO West")
    ;

    /**
     * The default region that new customers in the US are encouraged to use
     * when using AWS services for the first time.
     */
    public static final Regions DEFAULT_REGION = US_WEST_2;

    private final String name;
    private final String description;

    private Regions(String name, String description) {
        this.name = name;
        this.description = description;
    }

    /**
     * The name of this region, used in the regions.xml file to identify it.
     */
    public String getName() {
        return name;
    }

    /**
     * Descriptive readable name for this region.
     */
    public String getDescription() {
        return description;
    }

    /**
     * Returns a region enum corresponding to the given region name.
     *
     * @param regionName
     *            The name of the region. Ex.: eu-west-1
     * @return Region enum representing the given region name.
     */
    public static Regions fromName(String regionName) {
        for (Regions region : Regions.values()) {
            if (region.getName().equals(regionName)) {
                return region;
            }
        }
        throw new IllegalArgumentException("Cannot create enum from " + regionName + " value!");
    }

    /**
     * Returns a Region object representing the region the application is
     * running in, when running in EC2. If this method is called from a non-EC2
     * environment, it will return null.
     */
    public static Region getCurrentRegion() {
        try {
            final String region = EC2MetadataUtils.getEC2InstanceRegion();
            if (region != null)
                return RegionUtils.getRegion(region);
        } catch (AmazonClientException e) {
            LogFactory.getLog(Regions.class).debug(
                "Ignoring failure to retrieve the region: " + e.getMessage());
        }
        return null;
    }
}

所以，getCurrentRegion看起来Regions像是另一种选择。如果您成功地使用其中之一来达到您的目的，那么重构就会很容易，并且相应地重构也是有意义的。

3. 复制并重命名该类

如果前两个选项对您来说不可行，那么您可以复制并重命名该class，这样您就可以确保即使内部 API 发生更改，该方法也将保持不变。这不是一个非常优雅的方法，也不容易实现，因为它class具有依赖性，因此，您将遇到一些难以解决的困难，但我们事先知道这是一个可能的解决方案。

4. 最后是自己动手的方法

这是一篇有关检索实例元数据的文章：https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/instancedata-data-retrieval.html

我们可以看到，在实例的元数据信息中，您可以找到区域： https: //docs.aws.amazon.com/AWSEC2/latest/UserGuide/instancedata-data-categories.html

使用curl和jq的命令示例如下所示

curl -s http://169.254.169.254/latest/dynamic/instance-identity/document | jq -r .region

可以在这里找到： https: //www.howtouselinux.com/post/find-ec2-instance-region-info-in-aws