The "config" package is no longer used and will be removed as part
of the 0.12 release cleanup. Since configschema is part of the
"new world" of configuration modelling, it makes more sense for
it to live as a subdirectory of the newer "configs" package.
Since schemas are required to interpret provider, resource, and
provisioner attributes in configs, states, and plans, these helpers intend
to make it easier to gather up the the necessary provider types in order
to preload all of the needed schemas before beginning further processing.
Config.ProviderTypes returns directly the list of provider types, since
at this level further detail is not useful: we've not yet run the
provider allocation algorithm, and so the only thing we can reliably
extract here is provider types themselves.
State.ProviderAddrs and Plan.ProviderAddrs each return a list of
absolute provider addresses, which can then be turned into a list of
provider types using the new helper providers.AddressedTypesAbs.
Since we're already using configs.Config throughout core, this also
updates the terraform.LoadSchemas helper to use Config.ProviderTypes
to find the necessary providers, rather than implementing its own
discovery logic. states.State is not yet plumbed in, so we cannot yet
use State.ProviderAddrs to deal with the state but there's a TODO comment
to remind us to update that in a later commit when we swap out
terraform.State for states.State.
A later commit will probably refactor this further so that we can easily
obtain schema for the providers needed to interpret a plan too, but that
is deferred here because further work is required to make core work with
the new plan types first. At that point, terraform.LoadSchemas may become
providers.LoadSchemas with a different interface that just accepts lists
of provider and provisioner names that have been gathered by the caller
using these new helpers.
We now fetch all of the necessary schemas during context creation, so we
can just thread that repository of schemas through into EvalContext and
Evaluator and access the schemas as needed without any further fetching.
This requires updating a few tests to have a valid Provider address in
their state objects, because we need that in order to trigger the loading
of the relevant schema.
Previously we fetched schemas during the AttachSchemaTransformer,
potentially multiple times as that was re-run for each graph built. Now
we fetch the schemas just once during context construction, passing that
result into each of the graph builders.
This only addresses the schema accesses during graph construction. We're
still separately loading schemas during the main walk for evaluation
purposes. This will be addressed in a later commit.
In order to parse provider, resource and data source configuration from
HCL2 config files, we need to know the relevant configuration schema.
This new method allows Terraform Core to request these from a provider.
This is a breaking change to this interface, so all of its implementers
in this package are updated too. This includes concrete implementations
of the new method in helper/schema that use the schema conversion code
added in an earlier commit to produce a configschema.Block automatically.
Plugins compiled against prior versions of helper/schema will not have
support for this method, and so calls to them will fail. Callers of
this new method will therefore need to sniff for support using the
SchemaAvailable field added to both ResourceType and DataSource.
This careful handling will need to persist until next time we increment
the plugin protocol version, at which point we can make the breaking
change of requiring this information to be available.
