This is an iteration on the great work done by @dalehamel in PRs #2095
and #2109.
The core team went back and forth on how to best model Spot Instance
Requests, requesting and then rejecting a separate-resource
implementation in #2109.
After more internal discussion, we landed once again on a separate
resource to model Spot Instance Requests. Out of respect for
@dalehamel's already-significant donated time, with this I'm attempting
to pick up the work to take this across the finish line.
Important architectural decisions represented here:
* Spot Instance Requests are always of type "persistent", to properly
match Terraform's declarative model.
* The spot_instance_request resource exports several attributes that
are expected to be constantly changing as the spot market changes:
spot_bid_status, spot_request_state, and instance_id. Creating
additional resource dependencies based on these attributes is not
recommended, as Terraform diffs will be continually generated to keep
up with the live changes.
* When a Spot Instance Request is deleted/canceled, an attempt is made
to terminate the last-known attached spot instance. Race conditions
dictate that this attempt cannot guarantee that the associated spot
instance is terminated immediately.
Implementation notes:
* This version of aws_spot_instance_request borrows a lot of common
code from aws_instance.
* In order to facilitate borrowing, we introduce `awsInstanceOpts`, an
internal representation of instance details that's meant to be shared
between resources. The goal here would be to refactor ASG Launch
Configurations to use the same struct.
* The new aws_spot_instance_request acc. test is passing.
* All aws_instance acc. tests remain passing.
