[amazon-ec2] How to get the instance id from within an ec2 instance?

How can I find out the instance id of an ec2 instance from within the ec2 instance?

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.

You can just make a HTTP request to GET any Metadata by passing the your metadata parameters.

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

or

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

You won't be billed for HTTP requests to get Metadata and Userdata.

Else

You can use EC2 Instance Metadata Query Tool which is a simple bash script that uses curl to query the EC2 instance Metadata from within a running EC2 instance as mentioned in documentation.

Download the tool:

$ wget http://s3.amazonaws.com/ec2metadata/ec2-metadata

now run command to get required data.

$ec2metadata -i

Refer:

http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-instance-metadata.html

https://aws.amazon.com/items/1825?externalID=1825

Happy To Help.. :)

On Amazon Linux AMIs you can do:

$ ec2-metadata -i
instance-id: i-1234567890abcdef0

Or, on Ubuntu and some other linux flavours, ec2metadata --instance-id (This command may not be installed by default on ubuntu, but you can add it with sudo apt-get install cloud-utils)

As its name suggests, you can use the command to get other useful metadata too.

Use the /dynamic/instance-identity/document URL if you also need to query more than just your instance ID.

wget -q -O - http://169.254.169.254/latest/dynamic/instance-identity/document

This will get you JSON data such as this - with only a single request.

{
    "devpayProductCodes" : null,
    "privateIp" : "10.1.2.3",
    "region" : "us-east-1",
    "kernelId" : "aki-12345678",
    "ramdiskId" : null,
    "availabilityZone" : "us-east-1a",
    "accountId" : "123456789abc",
    "version" : "2010-08-31",
    "instanceId" : "i-12345678",
    "billingProducts" : null,
    "architecture" : "x86_64",
    "imageId" : "ami-12345678",
    "pendingTime" : "2014-01-23T45:01:23Z",
    "instanceType" : "m1.small"
}

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 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

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}/";

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

Simply check the var/lib/cloud/instance symlink, it should point to /var/lib/cloud/instances/{instance-id} where {instance_id} is your instance-id.

The latest Java SDK has EC2MetadataUtils:

In Java:

import com.amazonaws.util.EC2MetadataUtils;
String myId = EC2MetadataUtils.getInstanceId();

In Scala:

import com.amazonaws.util.EC2MetadataUtils
val myid = EC2MetadataUtils.getInstanceId

FWIW I wrote a FUSE filesystem to provide access to the EC2 metadata service: https://bitbucket.org/dgc/ec2mdfs . I run this on all custom AMIs; it allows me to use this idiom: cat /ec2/meta-data/ami-id

A more contemporary solution.

From Amazon Linux the ec2-metadata command is already installed.

From the terminal

ec2-metadata -help

Will give you the available options

ec2-metadata -i

will return

instance-id: yourid

You can try this:

#!/bin/bash
aws_instance=$(wget -q -O- http://169.254.169.254/latest/meta-data/instance-id)
aws_region=$(wget -q -O- http://169.254.169.254/latest/meta-data/hostname)
aws_region=${aws_region#*.}
aws_region=${aws_region%%.*}
aws_zone=`ec2-describe-instances $aws_instance --region $aws_region`
aws_zone=`expr match "$aws_zone" ".*\($aws_region[a-z]\)"`

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 powershell people:

(New-Object System.Net.WebClient).DownloadString("http://169.254.169.254/latest/meta-data/instance-id")

For 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]

On Ubuntu you can:

sudo apt-get install cloud-utils

And then you can:

EC2_INSTANCE_ID=$(ec2metadata --instance-id)

You can get most of the metadata associated with the instance this way:

ec2metadata --help
Syntax: /usr/bin/ec2metadata [options]

Query and display EC2 metadata.

If no options are provided, all options will be displayed

Options:
    -h --help               show this help

    --kernel-id             display the kernel id
    --ramdisk-id            display the ramdisk id
    --reservation-id        display the reservation id

    --ami-id                display the ami id
    --ami-launch-index      display the ami launch index
    --ami-manifest-path     display the ami manifest path
    --ancestor-ami-ids      display the ami ancestor id
    --product-codes         display the ami associated product codes
    --availability-zone     display the ami placement zone

    --instance-id           display the instance id
    --instance-type         display the instance type

    --local-hostname        display the local hostname
    --public-hostname       display the public hostname

    --local-ipv4            display the local ipv4 ip address
    --public-ipv4           display the public ipv4 ip address

    --block-device-mapping  display the block device id
    --security-groups       display the security groups

    --mac                   display the instance mac address
    --profile               display the instance profile
    --instance-action       display the instance-action

    --public-keys           display the openssh public keys
    --user-data             display the user data (not actually metadata)

If you wish to get the all instances id list in python here is the code:

import boto3

ec2=boto3.client('ec2')
instance_information = ec2.describe_instances()

for reservation in instance_information['Reservations']:
   for instance in reservation['Instances']:
      print(instance['InstanceId'])

For PHP:

$instance = json_decode(file_get_contents('http://169.254.169.254/latest/dynamic/instance-identity/document));
$id = $instance['instanceId'];

Edit per @John

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

In the question you have mentioned the user as root, one thing I should mention is that the instance ID is not dependent on the user.

For Node developers,

var meta  = new AWS.MetadataService();

meta.request("/latest/meta-data/instance-id", function(err, data){
    console.log(data);
});

For C++ (using cURL):

    #include <curl/curl.h>

    //// cURL to string
    size_t curl_to_str(void *contents, size_t size, size_t nmemb, void *userp) {
        ((std::string*)userp)->append((char*)contents, size * nmemb);
        return size * nmemb;
    };

    //// Read Instance-id 
    curl_global_init(CURL_GLOBAL_ALL); // Initialize cURL
    CURL *curl; // cURL handler
    CURLcode res_code; // Result
    string response;
    curl = curl_easy_init(); // Initialize handler
    curl_easy_setopt(curl, CURLOPT_URL, "http://169.254.169.254/latest/meta-data/instance-id");
    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, curl_to_str);
    curl_easy_setopt(curl, CURLOPT_WRITEDATA, &response);
    res_code = curl_easy_perform(curl); // Perform cURL
    if (res_code != CURLE_OK) { }; // Error
    curl_easy_cleanup(curl); // Cleanup handler
    curl_global_cleanup(); // Cleanup cURL

For Python:

import boto.utils
region=boto.utils.get_instance_metadata()['local-hostname'].split('.')[1]

which boils down to the one-liner:

python -c "import boto.utils; print boto.utils.get_instance_metadata()['local-hostname'].split('.')[1]"

Instead of local_hostname you could also use public_hostname, or:

boto.utils.get_instance_metadata()['placement']['availability-zone'][:-1]

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

To get the instance metadata use

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

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

For .NET People :

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

In Go you can use the goamz package.

import (
    "github.com/mitchellh/goamz/aws"
    "log"
)

func getId() (id string) {
    idBytes, err := aws.GetMetaData("instance-id")
    if err != nil {
        log.Fatalf("Error getting instance-id: %v.", err)
    }

    id = string(idBytes)

    return id
}

Here's the GetMetaData source.

Just Type:

ec2metadata --instance-id

Alternative approach for PHP:

$instance = json_decode(file_get_contents('http://169.254.169.254/latest/dynamic/instance-identity/document'),true);
$id = $instance['instanceId'];
print_r($instance);

That will provide a lot of data about the instance, all nicely packed in an array, no external dependencies. As it's a request that never failed or delayed for me it should be safe to do it that way, otherwise I'd go for curl()