cache resource providers to reduce expensive api call

internal/clients/builder.go

@@ -158,7 +158,10 @@ func Build(ctx context.Context, builder ClientBuilder) (*Client, error) {
 
 	if features.EnhancedValidationEnabled() {
 		location.CacheSupportedLocations(ctx, *resourceManagerEndpoint)
-		resourceproviders.CacheSupportedProviders(ctx, client.Resource.ProvidersClient)
+		_, err := resourceproviders.CachedSupportedProviders(ctx, client.Resource.ProvidersClient)
+		if err != nil {
+			log.Printf("[DEBUG] error retrieving providers: %+v. Enhanced validation will be unavailable", err)
+		}
 	}
 
 	return &client, nil

internal/provider/provider.go

@@ -453,14 +453,14 @@ func buildClient(ctx context.Context, p *schema.Provider, d *schema.ResourceData
 	if !skipProviderRegistration {
 		// List all the available providers and their registration state to avoid unnecessary
 		// requests. This also lets us check if the provider credentials are correct.
-		providerList, err := client.Resource.ProvidersClient.List(ctx, nil, "")
+		providerList, err := resourceproviders.CachedSupportedProviders(ctx, client.Resource.ProvidersClient)
 		if err != nil {
 			return nil, diag.Errorf("Unable to list provider registration status, it is possible that this is due to invalid "+
 				"credentials or the service principal does not have permission to use the Resource Manager API, Azure "+
 				"error: %s", err)
 		}
 
-		availableResourceProviders := providerList.Values()
+		availableResourceProviders := *providerList
 		requiredResourceProviders := resourceproviders.Required()
 
 		if err := resourceproviders.EnsureRegistered(ctx, *client.Resource.ProvidersClient, availableResourceProviders, requiredResourceProviders); err != nil {

internal/resourceproviders/azure.go

@@ -7,22 +7,10 @@ import (
 	"github.com/Azure/azure-sdk-for-go/profiles/2017-03-09/resources/mgmt/resources"
 )
 
-func availableResourceProviders(ctx context.Context, client *resources.ProvidersClient) (*[]string, error) {
-	providerNames := make([]string, 0)
-	providers, err := client.ListComplete(ctx, nil, "")
+func availableResourceProviders(ctx context.Context, client *resources.ProvidersClient) ([]resources.Provider, error) {
+	providers, err := client.List(ctx, nil, "")
 	if err != nil {
 		return nil, fmt.Errorf("listing Resource Providers: %+v", err)
 	}
-	for providers.NotDone() {
-		provider := providers.Value()
-		if provider.Namespace != nil {
-			providerNames = append(providerNames, *provider.Namespace)
-		}
-
-		if err := providers.NextWithContext(ctx); err != nil {
-			return nil, err
-		}
-	}
-
-	return &providerNames, nil
+	return providers.Values(), nil
 }

internal/resourceproviders/cache.go

@@ -2,22 +2,30 @@ package resourceproviders
 
 import (
 	"context"
-	"log"
 
 	"github.com/Azure/azure-sdk-for-go/profiles/2017-03-09/resources/mgmt/resources"
 )
 
 // cachedResourceProviders can be (validly) nil - as such this shouldn't be relied on
-var cachedResourceProviders *[]string
+var cachedResourceProviders *[]resources.Provider
 
-// CacheSupportedProviders attempts to retrieve the supported Resource Providers from the Resource Manager API
+// CachedSupportedProviders returns cached the supported Resource Providers, if not cached it attempts to retrieve from the Resource Manager API
 // and caches them, for used in enhanced validation
-func CacheSupportedProviders(ctx context.Context, client *resources.ProvidersClient) {
+func CachedSupportedProviders(ctx context.Context, client *resources.ProvidersClient) (*[]resources.Provider, error) {
+	if cachedResourceProviders != nil {
+		return cachedResourceProviders, nil
+	}
 	providers, err := availableResourceProviders(ctx, client)
 	if err != nil {
-		log.Printf("[DEBUG] error retrieving providers: %s. Enhanced validation will be unavailable", err)
-		return
+		return nil, err
 	}
-
-	cachedResourceProviders = providers
+	cached := make([]resources.Provider, 0)
+	for _, provider := range providers {
+		cached = append(cached, resources.Provider{
+			Namespace:         provider.Namespace,
+			RegistrationState: provider.RegistrationState,
+		})
+	}
+	cachedResourceProviders = &cached
+	return cachedResourceProviders, nil
 }

internal/resourceproviders/validation.go

@@ -41,13 +41,19 @@ func enhancedValidation(i interface{}, k string) ([]string, []error) {
 
 	found := false
 	for _, provider := range *cachedResourceProviders {
-		if provider == v {
+		if provider.Namespace != nil && *provider.Namespace == v {
 			found = true
 		}
 	}
 
 	if !found {
-		providersJoined := strings.Join(*cachedResourceProviders, ", ")
+		cachedResourceProvidersNames := make([]string, 0)
+		for _, provider := range *cachedResourceProviders {
+			if provider.Namespace != nil {
+				cachedResourceProvidersNames = append(cachedResourceProvidersNames, *provider.Namespace)
+			}
+		}
+		providersJoined := strings.Join(cachedResourceProvidersNames, ", ")
 		return nil, []error{
 			fmt.Errorf("%q was not found in the list of supported Resource Providers: %q", v, providersJoined),
 		}

internal/resourceproviders/validation_test.go

@@ -3,7 +3,9 @@ package resourceproviders
 import (
 	"testing"
 
+	"github.com/Azure/azure-sdk-for-go/profiles/2017-03-09/resources/mgmt/resources"
 	"github.com/hashicorp/terraform-provider-azurerm/internal/features"
+	"github.com/hashicorp/terraform-provider-azurerm/utils"
 )
 
 func TestEnhancedValidationDisabled(t *testing.T) {
@@ -68,7 +70,7 @@ func TestEnhancedValidationEnabled(t *testing.T) {
 		},
 	}
 	enhancedEnabled = true
-	cachedResourceProviders = &[]string{"Microsoft.Compute"}
+	cachedResourceProviders = &[]resources.Provider{{Namespace: utils.String("Microsoft.Compute")}}
 	defer func() {
 		enhancedEnabled = features.EnhancedValidationEnabled()
 		cachedResourceProviders = nil