The previous strategy for provisioning infrastructure targets was to use
the cheapest instances that could reliably perform as Vault cluster
nodes. With this change we introduce a new model for target node
infrastructure. We've replaced on-demand instances for a spot
fleet. While the spot price fluctuates based on dynamic pricing,
capacity, region, instance type, and platform, cost savings for our
most common combinations range between 20-70%.
This change only includes spot fleet targets for Vault clusters.
We'll be updating our Consul backend bidding in another PR.
* Create a new `vault_cluster` module that handles installation,
configuration, initializing, and unsealing Vault clusters.
* Create a `target_ec2_instances` module that can provision a group of
instances on-demand.
* Create a `target_ec2_spot_fleet` module that can bid on a fleet of
spot instances.
* Extend every Enos scenario to utilize the spot fleet target acquisition
strategy and the `vault_cluster` module.
* Update our Enos CI modules to handle both the `aws-nuke` permissions
and also the privileges to provision spot fleets.
* Only use us-east-1 and us-west-2 in our scenario matrices as costs are
lower than us-west-1.
Signed-off-by: Ryan Cragun <me@ryan.ec>
