As explained in pulumi/pulumi-fabric#293, we were a little ad-hoc in
how configuration was "applied" to resource providers.
In fact, config wasn't ever communicated directly to providers; instead,
the resource providers would simply ask the engine to read random heap
locations (via tokens). Now that we're on a plan where configuration gets
handed to the program at startup, and that's that, and where generally
speaking resource providers never communicate directly with the language
runtime, we need to take a different approach.
As such, the resource provider interface now offers a Configure RPC
method that the resource planning engine will invoke at the right
times with the right subset of configuration variables filtered to
just that provider's package. This fixespulumi/pulumi#293.
The existing implementation of the interface (backed by the file
system) has moved into cmd/lumi. The deployment service will start to
provide its own version.
`saveEnv` had a flag which would prevent an environment from being
overwritten if it already existed, which was only used by `lumi env
init`. Refactor the code so the check is done inside `lumi` instead of
against this API. We don't need this functionality for the service and
so requiring support for this at the API boundary for environments
feels like a bad idea.
We'd like to abstract out environment CRUD operations and I'd prefer
not to have to bake in the conspect of a file name like thing in the
abstraction. Since we were not really using this feature many places,
let's just get rid of it.
This refactors the engine so all of the APIs on it are instance
methods on the type instead of raw methods that float around and use
data from a global engine.
A mechcanical change as we remove the global `E` and then make
anything that interacted with that in pkg/engine to be an instance
method and the dealing with the fallout.
