Comment 0 for bug 1660385

Many cloud providers mimic the EC2 Metadata service [1] in order to provide
a level of EC2 compatibility for images. This is quite useful and allows
image portability.

Because this is a network based metadata service, cloud-init opportunistically
poll an IPv4 link local address (http://169.254.169.254) to determine if there
is metadata available. That can have negative side affects such as timeouts.

AWS has recently begun providing a way for instances to determine if they
are running on EC2 [2].

Cloud-init will change its behavior to only attempt to find the EC2 metadata
service only if it has determined itself to be running on EC2 or another
known cloud provider which provides an EC2 metadata service.

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[1] http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-instance-metadata.html
[2] http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/identify_ec2_instances.html