How do you get AWS VPC EC2 instances to be able to see the AWS APIs?
- by Peter Mounce
We're spinning up infrastructure inside of an AWS VPC via CloudFormation.
We're using auto-scaling groups to bring up VPC-EC2 instances (so, we don't bring up instances directly; ASGs manage that).
Inside of a PVC, EC2 instances only have a private IP; they cannot see the outside world without further work.
When these instances spin up, we have some bootstrap tasks that require talking to the various AWS APIs. We also have some ongoing tasks that require AWS API traffic.
How are you tackling this apparent chicken-egg problem?
We've read about:
NAT instances - but don't like this so much because it's another layer to our stack.
assigning elastic-IPs to each VPC instance that needs to talk - but a) they all do, and b) since we're using ASGs, we don't know which instances to assign EIPs to at provision-time, and c) we'd need to set up something to monitor those ASGs and assign EIPs when instances are terminated and replaced
spinning up an instance (actually, a load-balanced pair, probably spanning AZs) to act as an AWS-API proxy for all API traffic
I guess I'm wondering whether there's some kind of back-door we can open that allows our VPC EC2 instances access to the AWS API endpoints, but nothing else, for cheap-complexity setup, that doesn't add another network-hop layer to our infrastructure for serving requests.
