Retrieving instance metadata - Amazon Elastic Compute Cloud

Retrieving instance metadata

Because your instance metadata is available from your running instance, you do not need to use the Amazon EC2 console or the AWS CLI. This can be helpful when you're writing scripts to run from your instance. For example, you can access the local IP address of your instance from instance metadata to manage a connection to an external application.

Instance metadata is divided into categories. For a description of each instance metadata category, see Instance metadata categories.

To view all categories of instance metadata from within a running instance, use the following URI.

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

The IP address 169.254.169.254 is a link-local address and is valid only from the instance. For more information, see Link-local address on Wikipedia.

Note that you are not billed for HTTP requests used to retrieve instance metadata and user data.

The command format is different, depending on whether you use IMDSv1 or IMDSv2. By default, you can use both instance metadata services. To require the use of IMDSv2, see Configuring the instance metadata service.

You can use PowerShell cmdlets to retrieve the URI. For example, if you are running version 3.0 or later of PowerShell, use the following cmdlet.

IMDSv2
PS C:\> $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/
IMDSv1
PS C:\> Invoke-RestMethod -uri http://169.254.169.254/latest/meta-data/

If you don't want to use PowerShell, you can install a third-party tool such as GNU Wget or cURL.

Important

If you do install a third-party tool on a Windows instance, ensure that you read the accompanying documentation carefully, as the method of calling the HTTP and the output format might be different from what is documented here.

Responses and error messages

All instance metadata is returned as text (HTTP content type text/plain).

A request for a specific metadata resource returns the appropriate value, or a 404 - Not Found HTTP error code if the resource is not available.

A request for a general metadata resource (the URI ends with a /) returns a list of available resources, or a 404 - Not Found HTTP error code if there is no such resource. The list items are on separate lines, terminated by line feeds (ASCII 10).

For requests made using Instance Metadata Service Version 2, the following HTTP error codes can be returned:

  • 400 - Missing or Invalid Parameters – The PUT request is not valid.

  • 401 - Unauthorized – The GET request uses an invalid token. The recommended action is to generate a new token.

  • 403 - Forbidden – The request is not allowed or the instance metadata service is turned off.

Examples of retrieving instance metadata

Get the available versions of the instance metadata

This example gets the available versions of the instance metadata. These versions do not necessarily correlate with an Amazon EC2 API version. The earlier versions are available to you in case you have scripts that rely on the structure and information present in a previous version.

IMDSv2
PS C:\> $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/ 1.0 2007-01-19 2007-03-01 2007-08-29 2007-10-10 2007-12-15 2008-02-01 2008-09-01 2009-04-04 2011-01-01 2011-05-01 2012-01-12 2014-02-25 2014-11-05 2015-10-20 2016-04-19 2016-06-30 2016-09-02 latest
IMDSv1
PS C:\> Invoke-RestMethod -uri http://169.254.169.254/ 1.0 2007-01-19 2007-03-01 2007-08-29 2007-10-10 2007-12-15 2008-02-01 2008-09-01 2009-04-04 2011-01-01 2011-05-01 2012-01-12 2014-02-25 2014-11-05 2015-10-20 2016-04-19 2016-06-30 2016-09-02 latest

Get the top-level metadata items

This example gets the top-level metadata items. For more information, see Instance metadata categories.

IMDSv2
PS C:\> $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/ ami-id ami-launch-index ami-manifest-path block-device-mapping/ hostname iam/ instance-action instance-id instance-life-cycle instance-type local-hostname local-ipv4 mac metrics/ network/ placement/ profile public-hostname public-ipv4 public-keys/ reservation-id security-groups services/
IMDSv1
PS C:\> Invoke-RestMethod -uri http://169.254.169.254/latest/meta-data/ 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/

The following examples get the values of some of the top-level metadata items that were obtained in the preceding example. The IMDSv2 requests use the stored token that was created in the preceding example command, assuming it has not expired.

IMDSv2
PS C:\> Invoke-RestMethod -Headers @{"X-aws-ec2-metadata-token" = $token} -Method GET -Uri http://169.254.169.254/latest/meta-data/ami-id ami-0abcdef1234567890
IMDSv1
PS C:\> Invoke-RestMethod -uri http://169.254.169.254/latest/meta-data/ami-id ami-0abcdef1234567890

 

IMDSv2
PS C:\> Invoke-RestMethod -Headers @{"X-aws-ec2-metadata-token" = $token} -Method GET -Uri http://169.254.169.254/latest/meta-data/reservation-id r-0efghijk987654321
IMDSv1
PS C:\> Invoke-RestMethod -uri http://169.254.169.254/latest/meta-data/reservation-id r-0efghijk987654321

 

IMDSv2
PS C:\> Invoke-RestMethod -Headers @{"X-aws-ec2-metadata-token" = $token} -Method GET -Uri http://169.254.169.254/latest/meta-data/local-hostname ip-10-251-50-12.ec2.internal
IMDSv1
PS C:\> Invoke-RestMethod -uri http://169.254.169.254/latest/meta-data/local-hostname ip-10-251-50-12.ec2.internal

 

IMDSv2
PS C:\> Invoke-RestMethod -Headers @{"X-aws-ec2-metadata-token" = $token} -Method GET -Uri http://169.254.169.254/latest/meta-data/public-hostname ec2-203-0-113-25.compute-1.amazonaws.com
IMDSv1
PS C:\> Invoke-RestMethod -uri http://169.254.169.254/latest/meta-data/public-hostname ec2-203-0-113-25.compute-1.amazonaws.com

Get the list of available public keys

This example gets the list of available public keys.

IMDSv2
PS C:\> $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/public-keys/ 0=my-public-key
IMDSv1
PS C:\> Invoke-RestMethod -uri http://169.254.169.254/latest/meta-data/public-keys/ 0=my-public-key

Show the formats in which public key 0 is available

This example shows the formats in which public key 0 is available.

IMDSv2
PS C:\> $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/public-keys/0/openssh-key openssh-key
IMDSv1
PS C:\> Invoke-RestMethod -uri http://169.254.169.254/latest/meta-data/public-keys/0/openssh-key openssh-key

Get public key 0 (in the OpenSSH key format)

This example gets public key 0 (in the OpenSSH key format).

IMDSv2
PS C:\> $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/public-keys/0/openssh-key ssh-rsa MIICiTCCAfICCQD6m7oRw0uXOjANBgkqhkiG9w0BAQUFADCBiDELMAkGA1UEBhMC VVMxCzAJBgNVBAgTAldBMRAwDgYDVQQHEwdTZWF0dGxlMQ8wDQYDVQQKEwZBbWF6 b24xFDASBgNVBAsTC0lBTSBDb25zb2xlMRIwEAYDVQQDEwlUZXN0Q2lsYWMxHzAd BgkqhkiG9w0BCQEWEG5vb25lQGFtYXpvbi5jb20wHhcNMTEwNDI1MjA0NTIxWhcN MTIwNDI0MjA0NTIxWjCBiDELMAkGA1UEBhMCVVMxCzAJBgNVBAgTAldBMRAwDgYD VQQHEwdTZWF0dGxlMQ8wDQYDVQQKEwZBbWF6b24xFDASBgNVBAsTC0lBTSBDb25z b2xlMRIwEAYDVQQDEwlUZXN0Q2lsYWMxHzAdBgkqhkiG9w0BCQEWEG5vb25lQGFt YXpvbi5jb20wgZ8wDQYJKoZIhvcNAQEBBQADgY0AMIGJAoGBAMaK0dn+a4GmWIWJ 21uUSfwfEvySWtC2XADZ4nB+BLYgVIk60CpiwsZ3G93vUEIO3IyNoH/f0wYK8m9T rDHudUZg3qX4waLG5M43q7Wgc/MbQITxOUSQv7c7ugFFDzQGBzZswY6786m86gpE Ibb3OhjZnzcvQAaRHhdlQWIMm2nrAgMBAAEwDQYJKoZIhvcNAQEFBQADgYEAtCu4 nUhVVxYUntneD9+h8Mg9q6q+auNKyExzyLwaxlAoo7TJHidbtS4J5iNmZgXL0Fkb FFBjvSfpJIlJ00zbhNYS5f6GuoEDmFJl0ZxBHjJnyp378OD8uTs7fLvjx79LjSTb NYiytVbZPQUQ5Yaxu2jXnimvw3rrszlaEXAMPLE my-public-key
IMDSv1
PS C:\> Invoke-RestMethod -uri http://169.254.169.254/latest/meta-data/public-keys/0/openssh-key ssh-rsa MIICiTCCAfICCQD6m7oRw0uXOjANBgkqhkiG9w0BAQUFADCBiDELMAkGA1UEBhMC VVMxCzAJBgNVBAgTAldBMRAwDgYDVQQHEwdTZWF0dGxlMQ8wDQYDVQQKEwZBbWF6 b24xFDASBgNVBAsTC0lBTSBDb25zb2xlMRIwEAYDVQQDEwlUZXN0Q2lsYWMxHzAd BgkqhkiG9w0BCQEWEG5vb25lQGFtYXpvbi5jb20wHhcNMTEwNDI1MjA0NTIxWhcN MTIwNDI0MjA0NTIxWjCBiDELMAkGA1UEBhMCVVMxCzAJBgNVBAgTAldBMRAwDgYD VQQHEwdTZWF0dGxlMQ8wDQYDVQQKEwZBbWF6b24xFDASBgNVBAsTC0lBTSBDb25z b2xlMRIwEAYDVQQDEwlUZXN0Q2lsYWMxHzAdBgkqhkiG9w0BCQEWEG5vb25lQGFt YXpvbi5jb20wgZ8wDQYJKoZIhvcNAQEBBQADgY0AMIGJAoGBAMaK0dn+a4GmWIWJ 21uUSfwfEvySWtC2XADZ4nB+BLYgVIk60CpiwsZ3G93vUEIO3IyNoH/f0wYK8m9T rDHudUZg3qX4waLG5M43q7Wgc/MbQITxOUSQv7c7ugFFDzQGBzZswY6786m86gpE Ibb3OhjZnzcvQAaRHhdlQWIMm2nrAgMBAAEwDQYJKoZIhvcNAQEFBQADgYEAtCu4 nUhVVxYUntneD9+h8Mg9q6q+auNKyExzyLwaxlAoo7TJHidbtS4J5iNmZgXL0Fkb FFBjvSfpJIlJ00zbhNYS5f6GuoEDmFJl0ZxBHjJnyp378OD8uTs7fLvjx79LjSTb NYiytVbZPQUQ5Yaxu2jXnimvw3rrszlaEXAMPLE my-public-key

Get the subnet ID for an instance

This example gets the subnet ID for an instance.

IMDSv2
PS C:\> $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/network/interfaces/macs/02:29:96:8f:6a:2d/subnet-id subnet-be9b61d7
IMDSv1
PS C:\> Invoke-RestMethod -uri http://169.254.169.254/latest/meta-data/network/interfaces/macs/02:29:96:8f:6a:2d/subnet-id subnet-be9b61d7

Throttling

We throttle queries to the instance metadata service on a per-instance basis, and we place limits on the number of simultaneous connections from an instance to the instance metadata service.

If you're using the instance metadata service to retrieve AWS security credentials, avoid querying for credentials during every transaction or concurrently from a high number of threads or processes, as this might lead to throttling. Instead, we recommend that you cache the credentials until they start approaching their expiry time.

If you are throttled while accessing the instance metadata service, retry your query with an exponential backoff strategy.

Limiting instance metadata service access

You can consider using local firewall rules to disable access from some or all processes to the instance metadata service.

Using Windows firewall to limit access

The following PowerShell example uses the built-in Windows firewall to prevent the Internet Information Server webserver (based on its default installation user ID of NT AUTHORITY\IUSR) from accessing 169.254.169.254. It uses a deny rule to reject all instance metadata requests (whether IMDSv1 or IMDSv2) from any process running as that user.

PS C:\> $blockPrincipal = New-Object -TypeName System.Security.Principal.NTAccount ("NT AUTHORITY\IUSR") PS C:\> $BlockPrincipalSID = $blockPrincipal.Translate([System.Security.Principal.SecurityIdentifier]).Value PS C:\> $BlockPrincipalSDDL = "D:(A;;CC;;;$BlockPrincipalSID)" PS C:\> New-NetFirewallRule -DisplayName "Block metadata service from IIS" -Action block -Direction out ` -Protocol TCP -RemoteAddress 169.254.169.254 -LocalUser $BlockPrincipalSDDL

Or, you can consider only allowing access to particular users or groups, by using allow rules. Allow rules might be easier to manage from a security perspective, because they require you to make a decision about what software needs access to instance metadata. If you use allow rules, it's less likely you will accidentally allow software to access the metadata service (that you did not intend to have access) if you later change the software or configuration on an instance. You can also combine group usage with allow rules, so that you can add and remove users from a permitted group without needing to change the firewall rule.

The following example prevents access to instance metadata by all processes running as an OS group specified in the variable blockPrincipal (in this example, the Windows group Everyone), except for processes specified in exceptionPrincipal (in this example, a group called trustworthy-users). You must specify both deny and allow principals because Windows Firewall, unlike the ! --uid-owner trustworthy-user rule in Linux iptables, does not provide a shortcut mechanism to allow only a particular principal (user or group) by denying all the others.

PS C:\> $blockPrincipal = New-Object -TypeName System.Security.Principal.NTAccount ("Everyone") PS C:\> $BlockPrincipalSID = $blockPrincipal.Translate([System.Security.Principal.SecurityIdentifier]).Value PS C:\> $exceptionPrincipal = New-Object -TypeName System.Security.Principal.NTAccount ("trustworthy-users") PS C:\> $ExceptionPrincipalSID = $exceptionPrincipal.Translate([System.Security.Principal.SecurityIdentifier]).Value PS C:\> $PrincipalSDDL = "O:LSD:(D;;CC;;;$ExceptionPrincipalSID)(A;;CC;;;$BlockPrincipalSID)" PS C:\> New-NetFirewallRule -DisplayName "Block metadata service for $($blockPrincipal.Value), exception: $($exceptionPrincipal.Value)" -Action block -Direction out ` -Protocol TCP -RemoteAddress 169.254.169.254 -LocalUser $PrincipalSDDL
Note

To use local firewall rules, you need to adapt the preceding example commands to suit your needs.

Using netsh rules to limit access

You can consider blocking all software using netsh rules, but those are much less flexible.

C:\> netsh advfirewall firewall add rule name="Block metadata service altogether" dir=out protocol=TCP remoteip=169.254.169.254 action=block
Note
  • To use local firewall rules, you need to adapt the preceding example commands to suit your needs.

  • netsh rules must be set from an elevated command prompt, and can’t be set to deny or allow particular principals.