Add provider plugin interface and types

This adds the new interface for the resource providers. The methods here
closely follow the grpc service methods, using the types expected in
terraform core

provider/doc.go

@@ -0,0 +1,3 @@
+// Package provider contains the interface and primary types required to
+// implement a Terraform resource provider.
+package provider

provider/provider.go

@@ -0,0 +1,270 @@
+package provider
+
+import (
+	"github.com/hashicorp/terraform/config/configschema"
+	"github.com/hashicorp/terraform/tfdiags"
+	"github.com/zclconf/go-cty/cty"
+)
+
+// Interface represents the set of methods required for a complete resource
+// provider plugin.
+type Interface interface {
+	// GetSchema returns the complete schema for the provider.
+	GetSchema() GetSchemaResponse
+
+	// ValidateProviderConfig allows the provider to validate the configuration
+	// values.
+	ValidateProviderConfig(ValidateProviderConfigRequest) ValidateProviderConfigResponse
+
+	// ValidateResourceTypeConfig allows the provider to validate the resource
+	// configuration values.
+	ValidateResourceTypeConfig(ValidateResourceTypeConfigRequest) ValidateResourceTypeConfigResponse
+
+	// ValidateDataSource allows the provider to validate the data source
+	// configuration values.
+	ValidateDataSourceConfig(ValidateDataSourceConfigRequest) ValidateDataSourceConfigResponse
+
+	// UpgradeResourceState is called when the state loader encounters an
+	// instance state whose schema version is less than the one reported by the
+	// currently-used version of the corresponding provider, and the upgraded
+	// result is used for any further processing.
+	UpgradeResourceState(UpgradeResourceStateRequest) UpgradeResourceStateResponse
+
+	// Configure configures and initialized the provider.
+	Configure(ConfigureRequest) ConfigureResponse
+
+	// Stop is called when the provider should halt any in-flight actions.
+	//
+	// Stop should not block waiting for in-flight actions to complete. It
+	// should take any action it wants and return immediately acknowledging it
+	// has received the stop request. Terraform will not make any further API
+	// calls to the provider after Stop is called.
+	//
+	// The error returned, if non-nil, is assumed to mean that signaling the
+	// stop somehow failed and that the user should expect potentially waiting
+	// a longer period of time.
+	Stop() error
+
+	// ReadResource refreshes a resource and returns its current state.
+	ReadResource(ReadResourceRequest) ReadResourceResponse
+
+	// PlanResourceChange takes the current state and proposed state of a
+	// resource, and returns the planned final state.
+	PlanResourceChange(PlanResourceChangeRequest) PlanResourceChangeResponse
+
+	// ApplyResourceChange takes the planned state for a resource, which may
+	// yet contain unknown computed values, and applies the changes returning
+	// the final state.
+	ApplyResourceChange(ApplyResourceChangeRequest) ApplyResourceChangeResponse
+
+	// ImportResourceState requests that the given resource be imported.
+	ImportResourceState(ImportResourceStateRequest) ImportResourceStateResponse
+
+	// ReadDataSource returns the data source's current state.
+	ReadDataSource(ReadDataSourceRequest) ReadDataSourceResponse
+}
+
+type GetSchemaResponse struct {
+	// Provider is the schema for the provider itself.
+	Provider *configschema.Block
+
+	// ResourceTypes map the resource type name to that type's schema.
+	ResourceTypes map[string]*configschema.Block
+
+	// DataSources maps the data source name to that data source's schema.
+	DataSources map[string]*configschema.Block
+
+	// Diagnostics contains any warnings or errors from the method call.
+	Diagnostics tfdiags.Diagnostics
+}
+
+type ValidateProviderConfigRequest struct {
+	// Config is the complete configuration value for the provider.
+	Config cty.Value
+}
+
+type ValidateProviderConfigResponse struct {
+	// Diagnostics contains any warnings or errors from the method call.
+	Diagnostics tfdiags.Diagnostics
+}
+
+type ValidateResourceTypeConfigRequest struct {
+	// TypeName is the name of the resource type to validate.
+	TypeName string
+
+	// Config is the configuration value to validate, which may contain unknown
+	// values.
+	Config cty.Value
+}
+
+type ValidateResourceTypeConfigResponse struct {
+	// Diagnostics contains any warnings or errors from the method call.
+	Diagnostics tfdiags.Diagnostics
+}
+
+type ValidateDataSourceConfigRequest struct {
+	// TypeName is the name of the data source type to validate.
+	TypeName string
+
+	// Config is the configuration value to validate, which may contain unknown
+	// values.
+	Config cty.Value
+}
+
+type ValidateDataSourceConfigResponse struct {
+	// Diagnostics contains any warnings or errors from the method call.
+	Diagnostics tfdiags.Diagnostics
+}
+
+type UpgradeResourceStateRequest struct {
+	// TypeName is the name of the resource type being upgraded
+	TypeName string
+
+	// Version is version of the schema that created the current state.
+	Version int
+
+	// PriorStateRaw is the state that needs to be upgraded to match the current
+	// schema version. Because the schema is unknown, this contains only the
+	// raw bytes as stored in the state. It is up to the provider to interpret
+	// the payload and return a state encoded with the current schema.
+	PriorStateRaw []byte
+}
+
+type UpgradeResourceStateResponse struct {
+	// State is the newly upgraded resource state.
+	State cty.Value
+
+	// Diagnostics contains any warnings or errors from the method call.
+	Diagnostics tfdiags.Diagnostics
+}
+
+type ConfigureRequest struct {
+	// Config is the complete configuration value for the provider.
+	Config cty.Value
+}
+
+type ConfigureResponse struct {
+	// Diagnostics contains any warnings or errors from the method call.
+	Diagnostics tfdiags.Diagnostics
+}
+
+type ReadResourceRequest struct {
+	// TypeName is the name of the resource type being read.
+	TypeName string
+
+	// PriorState contains the previously saved state value for this resource.
+	PriorState cty.Value
+}
+
+type ReadResourceResponse struct {
+	// NewState contains the current state of the resource.
+	NewState cty.Value
+
+	// Diagnostics contains any warnings or errors from the method call.
+	Diagnostics tfdiags.Diagnostics
+}
+
+type PlanResourceChangeRequest struct {
+	// TypeName is the name of the resource type to plan.
+	TypeName string
+
+	// PriorState is the previously saved state value for this resource.
+	PriorState cty.Value
+
+	// ProposedNewState is the expected state after the new configuration is
+	// applied. This is created by directly applying the configuration to the
+	// PriorState. The provider is then responsible for applying any further
+	// changes required to create the proposed final state.
+	ProposedNewState cty.Value
+
+	// PriorPrivate is the previously saved private data returned from the
+	// provider during the last apply.
+	PriorPrivate []byte
+}
+
+type PlanResourceChangeResponse struct {
+	// PlannedState is the expected state of the resource once the current
+	// configuration is applied.
+	PlannedState cty.Value
+
+	// RequiresReplace is the list of thee attributes that are requiring
+	// resource replacement.
+	RequiresReplace []cty.Path
+
+	// PlannedPrivate is an opaque blob that is not interpreted by terraform
+	// core. This will be saved and relayed back to the provider during
+	// ApplyResourceChange.
+	PlannedPrivate []byte
+
+	// Diagnostics contains any warnings or errors from the method call.
+	Diagnostics tfdiags.Diagnostics
+}
+
+type ApplyResourceChangeRequest struct {
+	// TypeName is the name of the resource type being applied.
+	TypeName string
+
+	// PriorState is the current state of resource.
+	PriorState cty.Value
+
+	// Planned state is the state returned from PlanResourceChange, and should
+	// represent the new state, minus any remaining computed attributes.
+	PlannedState cty.Value
+
+	// PlannedPrivate is the same value as returned by PlanResourceChange.
+	PlannedPrivate []byte
+}
+
+type ApplyResourceChangeResponse struct {
+	// NewState is the new complete state after applying the planned change.
+	// In the event of an error, NewState should represent the most recent
+	// known state of the resource, if it exists.
+	NewState cty.Value
+
+	// Connection is a map of string values used to return any information
+	// provisioners might require to connect to the resource.
+	Connection map[string]string
+
+	// Private is an opaque blob that will be stored in state along with the
+	// resource. It is intended only for interpretation by the provider itself.
+	Private []byte
+
+	// Diagnostics contains any warnings or errors from the method call.
+	Diagnostics tfdiags.Diagnostics
+}
+
+type ImportResourceStateRequest struct {
+	// TypeName is the name of the resource type to be imported.
+	TypeName string
+
+	// ID is a string with which the provider can identify the resource to be
+	// imported.
+	ID string
+}
+
+type ImportResourceStateResponse struct {
+	// State contains one or more state values for the imported resource. It is
+	// not required that these be complete, only that there is enough
+	// identifying information for the provider to successfully update the
+	// state in ReadResource.
+	State []cty.Value
+
+	// Diagnostics contains any warnings or errors from the method call.
+	Diagnostics tfdiags.Diagnostics
+}
+
+type ReadDataSourceRequest struct {
+	// TypeName is the name of the data source type to Read.
+	TypeName string
+
+	// Config is the complete configuration for the requested data source.
+	Config cty.Value
+}
+
+type ReadDataSourceResponse struct {
+	// State is the current state of the requested data source.
+	State cty.Value
+
+	// Diagnostics contains any warnings or errors from the method call.
+	Diagnostics tfdiags.Diagnostics
+}