Fetching AWS instance metadata from within Docker container?

Question

Is there a straightforward way to access AWS instance metadata from within a Docker container?

For example, when trying to fetch credentials for an IAM role on an EC2 instance, this would work on the instance itself:

http://169.254.169.254/latest/meta-data/iam/security-credentials/my_role

...but not from within a Docker container running on that EC2 instance.

Answer 1

There should be no difference between doing this in a container vs the host. The container can access EC2 metadata directly.

root@f1e5964e87e4:/# curl http://169.254.169.254/latest/meta-data/iam/security-credentials/myrole
{
  "Code" : "Success",
  "LastUpdated" : "2014-03-14T17:07:24Z",
  "Type" : "AWS-HMAC",
  "AccessKeyId" : "mykey",
  "SecretAccessKey" : "mysecret",
  "Token" : "mytoken",
  "Expiration" : "2014-03-14T23:09:39Z"
}

What do you see when you try the command from within the container? has an IAM role assigned?

Answer 2

As mentioned by @Ben Whaley in comments, below commands worked for me, mentioned in https://docs.aws.amazon.com/AmazonECS/latest/developerguide/windows_task_IAM_roles.html

$gateway = (Get-NetRoute | Where { $_.DestinationPrefix -eq '0.0.0.0/0' } | Sort-Object RouteMetric | Select NextHop).NextHop
$ifIndex = (Get-NetAdapter -InterfaceDescription "Hyper-V Virtual Ethernet*" | Sort-Object | Select ifIndex).ifIndex
New-NetRoute -DestinationPrefix 169.254.169.254/32 -InterfaceIndex $ifIndex -NextHop $gateway