SSH to EC2 instance and request to http://169.254.169.254/latest/meta-data for instance's information (public, private IP...)
By default, AWS has a limit of 20 instances per region.
(From September 2019, this has changed to a vCPU-based limit: https://aws.amazon.com/blogs/compute/preview-vcpu-based-instance-limits/)
Allows you to pay a fixed rate by the hour (or by the second) with no commitment
⇒ suitable for use cases where you dont want any long term commitment like testing and POCs, spiky, unpredictable workloads that cannot be interrupted
Provides you with a capacity reservation, and offer a significant discount on the hourly charge for an instance. Contract Terms are 1 Year or 3 Year Terms
These are unused EC2 instances that can bid for. Once your bid exceeds the current spot price the instance is launched. The instance can be shuted down anytime the spot price becomes greater than your bid price.
⇒ providing for even greater saving if your app have flexible start and end times, very low compute prices, urgent computing needs for large amounts of additional capacity, for a workload with several Reserved Instances reading from a queue, can use Spot Instances to alleviate heavy traffic in a cost-effective way
Physical EC2 server. reduce costs by allowing to use your existing server-bound software licenses (oracle license...)