group the provider transformations

The series of provider transformations is important, and often repeated.
Group these together in a single transform function.

terraform/graph_builder_apply.go

@@ -87,19 +87,8 @@ func (b *ApplyGraphBuilder) Steps() []GraphTransformer {
 		// Attach the state
 		&AttachStateTransformer{State: b.State},
 
-		// add configured providers
+		// add providers
-		&ProviderConfigTransformer{
+		TransformProviders(b.Providers, concreteProvider, b.Module),
-			Module:    b.Module,
-			Providers: b.Providers,
-			Concrete:  concreteProvider,
-		},
-
-		// Create all the providers
-		&MissingProviderTransformer{Providers: b.Providers, Concrete: concreteProvider},
-		&ProviderTransformer{},
-		&DisableProviderTransformer{},
-		&ParentProviderTransformer{},
-		&AttachProviderConfigTransformer{Module: b.Module},
 
 		// Destruction ordering
 		&DestroyEdgeTransformer{Module: b.Module, State: b.State},

terraform/graph_builder_import.go

@@ -52,19 +52,7 @@ func (b *ImportGraphBuilder) Steps() []GraphTransformer {
 		// Add the import steps
 		&ImportStateTransformer{Targets: b.ImportTargets},
 
-		// add configured providers
+		TransformProviders(b.Providers, concreteProvider, mod),
-		&ProviderConfigTransformer{
-			Module:    b.Module,
-			Providers: b.Providers,
-			Concrete:  concreteProvider,
-		},
-
-		// Provider-related transformations
-		&MissingProviderTransformer{Providers: b.Providers, Concrete: concreteProvider},
-		&ProviderTransformer{},
-		&DisableProviderTransformer{},
-		&ParentProviderTransformer{},
-		&AttachProviderConfigTransformer{Module: mod},
 
 		// This validates that the providers only depend on variables
 		&ImportProviderValidateTransformer{},

terraform/graph_builder_plan.go

@@ -93,19 +93,7 @@ func (b *PlanGraphBuilder) Steps() []GraphTransformer {
 		// Add root variables
 		&RootVariableTransformer{Module: b.Module},
 
-		// add configured providers
+		TransformProviders(b.Providers, b.ConcreteProvider, b.Module),
-		&ProviderConfigTransformer{
-			Module:    b.Module,
-			Providers: b.Providers,
-			Concrete:  b.ConcreteProvider,
-		},
-
-		// Create all the providers
-		&MissingProviderTransformer{Providers: b.Providers, Concrete: b.ConcreteProvider},
-		&ProviderTransformer{},
-		&DisableProviderTransformer{},
-		&ParentProviderTransformer{},
-		&AttachProviderConfigTransformer{Module: b.Module},
 
 		// Provisioner-related transformations. Only add these if requested.
 		GraphTransformIf(

terraform/graph_builder_refresh.go

@@ -126,19 +126,7 @@ func (b *RefreshGraphBuilder) Steps() []GraphTransformer {
 		// Add root variables
 		&RootVariableTransformer{Module: b.Module},
 
-		// add configured providers
+		TransformProviders(b.Providers, concreteProvider, b.Module),
-		&ProviderConfigTransformer{
-			Module:    b.Module,
-			Providers: b.Providers,
-			Concrete:  concreteProvider,
-		},
-
-		// Create all the providers
-		&MissingProviderTransformer{Providers: b.Providers, Concrete: concreteProvider},
-		&ProviderTransformer{},
-		&DisableProviderTransformer{},
-		&ParentProviderTransformer{},
-		&AttachProviderConfigTransformer{Module: b.Module},
 
 		// Add the local values
 		&LocalTransformer{Module: b.Module},

terraform/transform_destroy_edge.go

@@ -127,12 +127,7 @@ func (t *DestroyEdgeTransformer) Transform(g *Graph) error {
 		&AttachResourceConfigTransformer{Module: t.Module},
 		&AttachStateTransformer{State: t.State},
 
-		// Add providers since they can affect destroy order as well
+		TransformProviders(nil, providerFn, t.Module),
-		&MissingProviderTransformer{AllowAny: true, Concrete: providerFn},
-		&ProviderTransformer{},
-		&DisableProviderTransformer{},
-		&ParentProviderTransformer{},
-		&AttachProviderConfigTransformer{Module: t.Module},
 
 		// Add all the variables. We can depend on resources through
 		// variables due to module parameters, and we need to properly

terraform/transform_provider.go

@@ -6,9 +6,41 @@ import (
 	"strings"
 
 	"github.com/hashicorp/go-multierror"
+	"github.com/hashicorp/terraform/config/module"
 	"github.com/hashicorp/terraform/dag"
 )
 
+func TransformProviders(providers []string, concrete ConcreteProviderNodeFunc, mod *module.Tree) GraphTransformer {
+	// If we have no providers, let the MissingProviderTransformer add anything required.
+	// This is used by the destroy edge transformer's internal dependency graph.
+	allowAny := providers == nil
+
+	return GraphTransformMulti(
+		// Add providers from the config
+		&ProviderConfigTransformer{
+			Module:    mod,
+			Providers: providers,
+			Concrete:  concrete,
+		},
+		// Add any remaining missing providers
+		&MissingProviderTransformer{
+			AllowAny:  allowAny,
+			Providers: providers,
+			Concrete:  concrete,
+		},
+		// Connect the providers
+		&ProviderTransformer{},
+		// Disable unused providers
+		&DisableProviderTransformer{},
+		// Connect provider to their parent provider nodes
+		&ParentProviderTransformer{},
+		// Attach configuration to each provider instance
+		&AttachProviderConfigTransformer{
+			Module: mod,
+		},
+	)
+}
+
 // GraphNodeProvider is an interface that nodes that can be a provider
 // must implement.
 // ProviderName returns the name of the provider this satisfies.