httpTokens

Indicates whether a signed token header is required for instance metadata retrieval requests. The values affect the response as follows:

• required – When you retrieve the IAM role credentials, version 2.0 credentials are returned in all cases.

• optional – You can include a signed token header in your request to retrieve instance metadata, or you can leave it out. If you include it, version 2.0 credentials are returned for the IAM role. Otherwise, version 1.0 credentials are returned.

If you don't set a value, the EC2 launch default applies to the build and test instances. That default depends on the base AMI and any account-level instance metadata defaults. For more information, see Configure the instance metadata options in the Amazon EC2 User Guide.