Use the Instance Metadata Service to access instance metadata
You can access instance metadata from a running instance using one of the following methods:
-
Instance Metadata Service Version 2 (IMDSv2) – a session-oriented method
For examples, see Examples for IMDSv2.
-
Instance Metadata Service Version 1 (IMDSv1) – a request/response method
For examples, see Examples for IMDSv1.
By default, you can use either IMDSv1 or IMDSv2, or both.
You can configure the Instance Metadata Service (IMDS) on each instance so that local code or users must use IMDSv2. When you specify that IMDSv2 must be used, IMDSv1 no longer works. For information about how to configure your instance to use IMDSv2, see Configure the Instance Metadata Service options.
The PUT
or GET
headers are unique to IMDSv2. If
these headers are present in the request, then the request is intended for
IMDSv2. If no headers are present, it is assumed the request is intended for
IMDSv1.
For an extensive review of IMDSv2, see Add defense in depth against open firewalls, reverse proxies, and SSRF
vulnerabilities with enhancements to the EC2 Instance Metadata
Service
Topics
How Instance Metadata Service Version 2 works
IMDSv2 uses session-oriented requests. With session-oriented requests, you create a session token that defines the session duration, which can be a minimum of one second and a maximum of six hours. During the specified duration, you can use the same session token for subsequent requests. After the specified duration expires, you must create a new session token to use for future requests.
Note
The examples in this section use the IPv4 address of the Instance Metadata Service
(IMDS): 169.254.169.254
. If you are retrieving instance
metadata for EC2 instances over the IPv6 address, ensure that you enable and use
the IPv6 address instead: [fd00:ec2::254]
. The IPv6 address of the
IMDS is compatible with IMDSv2 commands. The IPv6 address is
only accessible on Nitro-based instances in an IPv6-supported subnet (dual stack or IPv6 only).
The following examples use a shell script and IMDSv2 to retrieve the top-level instance metadata items. Each example:
-
Creates a session token lasting six hours (21,600 seconds) using the
PUT
request -
Stores the session token header in a variable named
TOKEN
(Linux instances) ortoken
(Windows instances) -
Requests the top-level metadata items using the token
You can run two separate commands, or combine them.
Separate commands
First, generate a token using the following command.
[ec2-user ~]$
TOKEN=`curl -X PUT "http://169.254.169.254/latest/api/token" -H "X-aws-ec2-metadata-token-ttl-seconds: 21600"`
Then, use the token to generate top-level metadata items using the following command.
[ec2-user ~]$
curl -H "X-aws-ec2-metadata-token: $TOKEN" http://169.254.169.254/latest/meta-data/
Combined commands
You can store the token and combine the commands. The following example combines the above two commands and stores the session token header in a variable named TOKEN.
Note
If there is an error in creating the token, instead of a valid token, an error message is stored in the variable, and the command will not work.
[ec2-user ~]$
TOKEN=`curl -X PUT "http://169.254.169.254/latest/api/token" -H "X-aws-ec2-metadata-token-ttl-seconds: 21600"` \ && curl -H "X-aws-ec2-metadata-token: $TOKEN" http://169.254.169.254/latest/meta-data/
After you've created a token, you can reuse it until it expires. In the
following example command, which gets the ID of the AMI used to launch the
instance, the token that is stored in $TOKEN
in the previous
example is reused.
[ec2-user ~]$
curl -H "X-aws-ec2-metadata-token: $TOKEN" http://169.254.169.254/latest/meta-data/ami-id
PS C:\>
[string]$token = Invoke-RestMethod -Headers @{"X-aws-ec2-metadata-token-ttl-seconds" = "21600"} -Method PUT -Uri http://169.254.169.254/latest/api/token
PS C:\>
Invoke-RestMethod -Headers @{"X-aws-ec2-metadata-token" = $token} -Method GET -Uri http://169.254.169.254/latest/meta-data/
After you've created a token, you can reuse it until it expires. In the
following example command, which gets the ID of the AMI used to launch the
instance, the token that is stored in $token
in the previous
example is reused.
PS C:\>
Invoke-RestMethod -Headers @{"X-aws-ec2-metadata-token" = $token} ` -Method GET -uri http://169.254.169.254/latest/meta-data/ami-id
When you use IMDSv2 to request instance metadata, the request must include the following:
-
Use a
PUT
request to initiate a session to the instance metadata service. ThePUT
request returns a token that must be included in subsequentGET
requests to the instance metadata service. The token is required to access metadata using IMDSv2. -
Include the token in all
GET
requests to the IMDS. When token usage is set torequired
, requests without a valid token or with an expired token receive a401 - Unauthorized
HTTP error code.-
The token is an instance-specific key. The token is not valid on other EC2 instances and will be rejected if you attempt to use it outside of the instance on which it was generated.
-
The
PUT
request must include a header that specifies the time to live (TTL) for the token, in seconds, up to a maximum of six hours (21,600 seconds). The token represents a logical session. The TTL specifies the length of time that the token is valid and, therefore, the duration of the session. -
After a token expires, to continue accessing instance metadata, you must create a new session using another
PUT
. -
You can choose to reuse a token or create a new token with every request. For a small number of requests, it might be easier to generate and immediately use a token each time you need to access the IMDS. But for efficiency, you can specify a longer duration for the token and reuse it rather than having to write a
PUT
request every time you need to request instance metadata. There is no practical limit on the number of concurrent tokens, each representing its own session. IMDSv2 is, however, still constrained by normal IMDS connection and throttling limits. For more information, see Query throttling.
-
HTTP GET
and HEAD
methods are allowed in IMDSv2
instance metadata requests. PUT
requests are rejected if they contain
an X-Forwarded-For header.
By default, the response to PUT
requests has a response hop limit
(time to live) of 1
at the IP protocol level. If you need a bigger hop
limit, you can adjust it by using the modify-instance-metadata-options
Use a supported AWS SDK
To use IMDSv2, your EC2 instances must use an AWS SDK version that supports using IMDSv2. The latest versions of all the AWS SDKs support using IMDSv2.
Important
We recommend that you to stay up to date with SDK releases to keep up with the latest features, security updates, and underlying dependencies. Continued use of an unsupported SDK version is not recommended and is done at your discretion. For more information, see the AWS SDKs and Tools maintenance policy in the AWS SDKs and Tools Reference Guide.
The following are the minimum versions that support using IMDSv2:
-
AWS CLI
– 1.16.289 -
AWS Tools for Windows PowerShell
– 4.0.1.0 -
AWS SDK for .NET
– 3.3.634.1 -
AWS SDK for C++
– 1.7.229 -
AWS SDK for Go
– 1.25.38 -
AWS SDK for Go v2
– 0.19.0 -
AWS SDK for Java
– 1.11.678 -
AWS SDK for Java 2.x
– 2.10.21 -
AWS SDK for JavaScript in Node.js
– 2.722.0 -
AWS SDK for Kotlin
– 1.1.4 -
AWS SDK for PHP
– 3.147.7 -
AWS SDK for Python (Botocore)
– 1.13.25 -
AWS SDK for Python (Boto3)
– 1.12.6 -
AWS SDK for Ruby
– 3.79.0
Examples for IMDSv2
Run the following examples on your Amazon EC2 instance to retrieve the instance metadata for IMDSv2.
On Windows instances, you can use Windows PowerShell or you can install cURL or wget. If you install a third-party tool on a Windows instance, ensure that you read the accompanying documentation carefully, as the calls and the output might be different from what is described here.
Examples
- Get the available versions of the instance metadata
- Get the top-level metadata items
- Get the values for metadata items
- Get the list of available public keys
- Show the formats in which public key 0 is available
- Get public key 0 (in the OpenSSH key format)
- Get the subnet ID for an instance
- Get the instance tags for an instance
Get the available versions of the instance metadata
This example gets the available versions of the instance metadata. Each version refers to an instance metadata build when new instance metadata categories were released. The instance metadata build versions do not correlate with the Amazon EC2 API versions. The earlier versions are available to you in case you have scripts that rely on the structure and information present in a previous version.
Get the top-level metadata items
This example gets the top-level metadata items. For more information about the items in the response, see Instance metadata categories.
Note that tags are included in this output only if you've allowed access. For more information, see Allow access to tags in instance metadata.
Get the values for metadata items
These examples get the values of some of the top-level metadata items that were obtained in the preceding example. These requests use the stored token that was created using the command in the previous example. The token must not be expired.
Get the list of available public keys
This example gets the list of available public keys.
Show the formats in which public key 0 is available
This example shows the formats in which public key 0 is available.
Get public key 0 (in the OpenSSH key format)
This example gets public key 0 (in the OpenSSH key format).
Get the subnet ID for an instance
This example gets the subnet ID for an instance.
Get the instance tags for an instance
If access to instance tags in the instance metadata is turned on, you can get the tags for a instance from instance metadata. For more information, see Retrieve tags from instance metadata.
Examples for IMDSv1
Run the following examples on your Amazon EC2 instance to retrieve the instance metadata for IMDSv1.
On Windows instances, you can use Windows PowerShell or you can install cURL or wget. If you install a third-party tool on a Windows instance, ensure that you read the accompanying documentation carefully, as the calls and the output might be different from what is described here.
Examples
- Get the available versions of the instance metadata
- Get the top-level metadata items
- Get the values for metadata items
- Get the list of available public keys
- Show the formats in which public key 0 is available
- Get public key 0 (in the OpenSSH key format)
- Get the subnet ID for an instance
- Get the instance tags for an instance
Get the available versions of the instance metadata
This example gets the available versions of the instance metadata. Each version refers to an instance metadata build when new instance metadata categories were released. The instance metadata build versions do not correlate with the Amazon EC2 API versions. The earlier versions are available to you in case you have scripts that rely on the structure and information present in a previous version.
Get the top-level metadata items
This example gets the top-level metadata items. For more information about the items in the response, see Instance metadata categories.
Note that tags are included in this output only if you've allowed access. For more information, see Allow access to tags in instance metadata.
Get the values for metadata items
These examples get the values of some of the top-level metadata items that were obtained in the previous example.
Get the list of available public keys
This example gets the list of available public keys.
Show the formats in which public key 0 is available
This example shows the formats in which public key 0 is available.
Get public key 0 (in the OpenSSH key format)
This example gets public key 0 (in the OpenSSH key format).
Get the subnet ID for an instance
This example gets the subnet ID for an instance.
Get the instance tags for an instance
If access to instance tags in the instance metadata is turned on, you can get the tags for a instance from instance metadata. For more information, see Retrieve tags from instance metadata.