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

ec2-metadata command (17)

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

Alternative approach for PHP:

$instance = json_decode(file_get_contents(''),true);
$id = $instance['instanceId'];

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()

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, "");
    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

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

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

For PHP:

$instance = json_decode(file_get_contents(';
$id = $instance['instanceId'];

Edit per @John

For Python:

import boto.utils

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:


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


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

    ec2metadata --instance-id

For powershell people:

(New-Object System.Net.WebClient).DownloadString("")

In Go you can use the goamz package.

import (

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.

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){

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.

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

    -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)

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.

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.

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

wget -q -O -

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

    "devpayProductCodes" : null,
    "privateIp" : "",
    "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"

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



wget -q -O -

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


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

now run command to get required data.

$ec2metadata -i


Happy To Help.. :)

on AWS Linux:

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



Using in variables:

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