动机:用户想检索aws实例元数据。

解决方案: IP地址169.254.169.254是一个链接本地地址(仅对实例有效)aws为我们提供了用于检索运行实例的元数据的专用Restful API的链接(注意，用于检索实例元数据和用户数据的HTTP请求不会收费)。其他文件

例子:

//Request:
curl http://169.254.169.254/latest/meta-data/instance-id

//Response
ami-123abc

你可以使用这个链接http://169.254.169.254/latest/meta-data/<metadata-field>获得你实例的额外元数据标签，只需选择正确的标签:

ami id ami-launch-index ami-manifest-path 块设备 映射 事件 冬眠 主机名 我 身份凭证 instance-action 实例id 实例类型 local-hostname local-ipv4 mac 指标 网络 放置 配置文件 预订标识 安全组 服务

Ruby:

require 'rubygems'
require 'aws-sdk'
require 'net/http'

metadata_endpoint = 'http://169.254.169.254/latest/meta-data/'
instance_id = Net::HTTP.get( URI.parse( metadata_endpoint + 'instance-id' ) )

ec2 = AWS::EC2.new()
instance = ec2.instances[instance_id]

请参阅有关该主题的EC2文档。

Run:

wget -q -O - http://169.254.169.254/latest/meta-data/instance-id

如果您需要从脚本中编程访问实例ID，

die() { status=$1; shift; echo "FATAL: $*"; exit $status; }
EC2_INSTANCE_ID="`wget -q -O - http://169.254.169.254/latest/meta-data/instance-id || die \"wget instance-id has failed: $?\"`"

下面是一个更高级的使用示例(检索实例ID以及可用性区域和区域等):

EC2_INSTANCE_ID="`wget -q -O - http://169.254.169.254/latest/meta-data/instance-id || die \"wget instance-id has failed: $?\"`"
test -n "$EC2_INSTANCE_ID" || die 'cannot obtain instance-id'
EC2_AVAIL_ZONE="`wget -q -O - http://169.254.169.254/latest/meta-data/placement/availability-zone || die \"wget availability-zone has failed: $?\"`"
test -n "$EC2_AVAIL_ZONE" || die 'cannot obtain availability-zone'
EC2_REGION="`echo \"$EC2_AVAIL_ZONE\" | sed -e 's:\([0-9][0-9]*\)[a-z]*\$:\\1:'`"

您也可以使用curl而不是wget，这取决于您的平台上安装了什么。

对于Windows实例:

(wget http://169.254.169.254/latest/meta-data/instance-id).Content

or

(ConvertFrom-Json (wget http://169.254.169.254/latest/dynamic/instance-identity/document).Content).instanceId

我从http api为EC2元数据编写的c# .net类。 我将根据需要构建它的功能。如果你喜欢，你可以用它。

using Amazon;
using System.Net;

namespace AT.AWS
{
    public static class HttpMetaDataAPI
    {
        public static bool TryGetPublicIP(out string publicIP)
        {
            return TryGetMetaData("public-ipv4", out publicIP);
        }
        public static bool TryGetPrivateIP(out string privateIP)
        {
            return TryGetMetaData("local-ipv4", out privateIP);
        }
        public static bool TryGetAvailabilityZone(out string availabilityZone)
        {
            return TryGetMetaData("placement/availability-zone", out availabilityZone);
        }

        /// <summary>
        /// Gets the url of a given AWS service, according to the name of the required service and the AWS Region that this machine is in
        /// </summary>
        /// <param name="serviceName">The service we are seeking (such as ec2, rds etc)</param>
        /// <remarks>Each AWS service has a different endpoint url for each region</remarks>
        /// <returns>True if the operation was succesful, otherwise false</returns>
        public static bool TryGetServiceEndpointUrl(string serviceName, out string serviceEndpointStringUrl)
        {
            // start by figuring out what region this instance is in.
            RegionEndpoint endpoint;
            if (TryGetRegionEndpoint(out endpoint))
            {
                // now that we know the region, we can get details about the requested service in that region
                var details = endpoint.GetEndpointForService(serviceName);
                serviceEndpointStringUrl = (details.HTTPS ? "https://" : "http://") + details.Hostname;
                return true;
            }
            // satisfy the compiler by assigning a value to serviceEndpointStringUrl
            serviceEndpointStringUrl = null;
            return false;
        }
        public static bool TryGetRegionEndpoint(out RegionEndpoint endpoint)
        {
            // we can get figure out the region end point from the availability zone
            // that this instance is in, so we start by getting the availability zone:
            string availabilityZone;
            if (TryGetAvailabilityZone(out availabilityZone))
            {
                // name of the availability zone is <nameOfRegionEndpoint>[a|b|c etc]
                // so just take the name of the availability zone and chop off the last letter
                var nameOfRegionEndpoint = availabilityZone.Substring(0, availabilityZone.Length - 1);
                endpoint = RegionEndpoint.GetBySystemName(nameOfRegionEndpoint);
                return true;
            }
            // satisfy the compiler by assigning a value to endpoint
            endpoint = RegionEndpoint.USWest2;
            return false;
        }
        /// <summary>
        /// Downloads instance metadata
        /// </summary>
        /// <returns>True if the operation was successful, false otherwise</returns>
        /// <remarks>The operation will be unsuccessful if the machine running this code is not an AWS EC2 machine.</remarks>
        static bool TryGetMetaData(string name, out string result)
        {
            result = null;
            try { result = new WebClient().DownloadString("http://169.254.169.254/latest/meta-data/" + name); return true; }
            catch { return false; }
        }

/************************************************************
 * MetaData keys.
 *   Use these keys to write more functions as you need them
 * **********************************************************
ami-id
ami-launch-index
ami-manifest-path
block-device-mapping/
hostname
instance-action
instance-id
instance-type
local-hostname
local-ipv4
mac
metrics/
network/
placement/
profile
public-hostname
public-ipv4
public-keys/
reservation-id
security-groups
*************************************************************/
    }
}

类型:

ec2metadata --instance-id