Proposal: machine metadata

[ehazlett]

This will enable common metadata to be used with machines and not require the driver to implement them. Example, is swarm support. Each driver must implement SwarmXX due to the way the driver architecture is today. This will enable new functionality without requiring the driver to be updated.

Sample Metadata:

• Name
• Provider
• Region (us-east-1a, us-central-1a, nyc3)
• MachineType (i.e. t1.micro, f1.micro, etc)
• Memory

These also might need data from the driver so we will want to keep that in mind when refactoring the driver architecture. For example, instead of binding t1.micro in the metadata, we would do a lookup from the driver for something like driver.GetMachineType to account for resizes, etc.

Refs #553

[nathanleclaire]

I'm having a hard time wrapping my head around what this is exactly, although I think I might understand. Essentially there would be some kind of common base that the drivers use, e.g.:

type SomeDriver struct {
    metadata *drivers.Metadata
}

// ... now implement the rest of the methods

?

[ehazlett]

Correct. If we refactor the internal api / store this might not be necessary. But for now, the idea was that instead of having to add something like SwarmHost etc. for each driver, the metadata would be able to hold that.

[nathanleclaire]

I think this is covered by @hairyhenderson BaseDriver PR