How to get the instance id from within an ec2 instance?

See the EC2 documentation on the subject.

Run:

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

If you need programmatic access to the instance ID from within a script,

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: $?\"`"

Here is an example of a more advanced use (retrieve instance ID as well as availability zone and region, etc.):

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:'`"

You may also use curl instead of wget, depending on what is installed on your platform.

on AWS Linux:

ec2-metadata --instance-id | cut -d " " -f 2

Output:

i-33400429

Using in variables:

ec2InstanceId=$(ec2-metadata --instance-id | cut -d " " -f 2);
ls "log/${ec2InstanceId}/";

For all ec2 machines, the instance-id can be found in file:

    /var/lib/cloud/data/instance-id

You can also get instance id by running the following command:

    ec2metadata --instance-id

For .NET People :

string instanceId = new StreamReader(
      HttpWebRequest.Create("http://169.254.169.254/latest/meta-data/instance-id")
      .GetResponse().GetResponseStream())
    .ReadToEnd();

See this post - note that the IP address in the URL given is constant (which confused me at first), but the data returned is specific to your instance.

A c# .net class I wrote for EC2 metadata from the http api. I will build it up with functionality as needed. You can run with it if you like it.

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
*************************************************************/
    }
}

Motivation: User would like to Retrieve aws instance metadata.

Solution: The IP address 169.254.169.254 is a link-local address (and is valid only from the instance) aws gives us link with dedicated Restful API for Retrieving metadata of our running instance (Note that you are not billed for HTTP requests used to retrieve instance metadata and user data) . for Additional Documentation

Example:

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

//Response
ami-123abc

You able to get additional metadata labels of your instance using this link http://169.254.169.254/latest/meta-data/<metadata-field> just choose the right tags:

1. ami-id
2. ami-launch-index
3. ami-manifest-path
4. block-device
5. mapping
6. events
7. hibernation
8. hostname
9. iam
10. identity-credentials
11. instance-action
12. instance-id
13. instance-type
14. local-hostname
15. local-ipv4
16. mac
17. metrics
18. network
19. placement
20. profile
21. reservation-id
22. security-groups
23. services

To get the instance metadata use

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

For a Windows instance:

(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

Run this:

curl http://169.254.169.254/latest/meta-data/

You will be able to see different types of attributes which are provided by aws.

Use this link to view more

All meta-data related to EC2 resource can be accessed by the EC2 instance itself with the help of the following command being executed:

CURL :

http://169.254.169.254/<api-version>/meta-data/<metadata-requested>

For your case: "metadata-requested" should be instance-id , "api-version" is usually latest that can be used.

Additional Note: You can also get information related to below EC2 attributes using the above command.

ami-id, ami-launch-index, ami-manifest-path, block-device-mapping/, hostname, iam/, 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, services/,

For more details please follow this link : https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-instance-metadata.html

For AWS elastic beanstalk eb cli run eb tags --list

For .NET code it is very simple: var instanceId=Amazon.Util.EC2InstanceMetadata.InstanceId

Simple one line

cat /sys/devices/virtual/dmi/id/board_asset_tag

or

curl_cli -s http://169.254.169.254/latest/meta-data/instance-id

source: https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/identify_ec2_instances.html

You can also install awscli and use it to get all the info you wish:

AWS_DEFAULT_REGION=your-region aws ec2 describe-instances

You'll get lots of output so be sure to grep by your idetifier such as ip and print some more lines:

AWS_DEFAULT_REGION=your-region aws ec2 describe-instances | grep your-ip -A 10 | grep InstanceId