config: Add support for EndpointResolverWithOptions

config/config.go

@@ -34,8 +34,10 @@ var defaultAWSConfigResolvers = []awsConfigResolver{
 
 	// Sets the endpoint resolving behavior the API Clients will use for making
 	// requests to. Clients default to their own clients this allows overrides
-	// to be specified.
+	// to be specified. This value is deprecated, but we still need to set it for
+	// backwards compatability on config construction.
 	resolveEndpointResolver,
+	resolveEndpointResolverWithOptions,
 
 	// Sets the retry behavior API clients will use within their retry attempt
 	// middleware. Defaults to unset, allowing API clients to define their own

config/example_test.go

@@ -91,6 +91,20 @@ func ExampleWithEndpointResolver() {
 	_ = cfg
 }
 
+func ExampleWithEndpointResolverWithOptions() {
+	cfg, err := config.LoadDefaultConfig(context.TODO(),
+		config.WithEndpointResolverWithOptions(aws.EndpointResolverWithOptionsFunc(
+			func(service, region string, options ...interface{}) (aws.Endpoint, error) {
+				return aws.Endpoint{URL: "https://mock.amazonaws.com"}, nil
+			})),
+	)
+
+	if err != nil {
+		log.Fatal(err)
+	}
+	_ = cfg
+}
+
 func ExampleWithHTTPClient() {
 	cfg, err := config.LoadDefaultConfig(context.TODO(),
 		config.WithHTTPClient(awshttp.NewBuildableClient().

config/load_options.go

@@ -31,9 +31,19 @@ type LoadOptions struct {
 	HTTPClient HTTPClient
 
 	// EndpointResolver that can be used to provide or override an endpoint for the given
-	// service and region Please see the `aws.EndpointResolver` documentation on usage.
+	// service and region.
+	//
+	// See the `aws.EndpointResolver` documentation on usage.
+	//
+	// Deprecated: See EndpointResolverWithOptions
 	EndpointResolver aws.EndpointResolver
 
+	// EndpointResolverWithOptions that can be used to provide or override an endpoint for the given
+	// service and region.
+	//
+	// See the `aws.EndpointResolverWithOptions` documentation on usage.
+	EndpointResolverWithOptions aws.EndpointResolverWithOptions
+
 	// Retryer is a function that provides a Retryer implementation. A Retryer guides how HTTP requests should be
 	// retried in case of recoverable failures.
 	Retryer func() aws.Retryer
@@ -533,16 +543,37 @@ func (o LoadOptions) getEndpointResolver(ctx context.Context) (aws.EndpointResol
 }
 
 // WithEndpointResolver is a helper function to construct functional options
-// that sets endpoint resolver on LoadOptions. The EndpointResolver is set to nil,
+// that sets the EndpointResolver on LoadOptions. If the EndpointResolver is set to nil,
 // the EndpointResolver value is ignored. If multiple WithEndpointResolver calls
 // are made, the last call overrides the previous call values.
+//
+// Deprecated: See WithEndpointResolverWithOptions
 func WithEndpointResolver(v aws.EndpointResolver) LoadOptionsFunc {
 	return func(o *LoadOptions) error {
 		o.EndpointResolver = v
 		return nil
 	}
 }
 
+func (o LoadOptions) getEndpointResolverWithOptions(ctx context.Context) (aws.EndpointResolverWithOptions, bool, error) {
+	if o.EndpointResolverWithOptions == nil {
+		return nil, false, nil
+	}
+
+	return o.EndpointResolverWithOptions, true, nil
+}
+
+// WithEndpointResolverWithOptions is a helper function to construct functional options
+// that sets the EndpointResolverWithOptions on LoadOptions. If the EndpointResolverWithOptions is set to nil,
+// the EndpointResolver value is ignored. If multiple WithEndpointResolver calls
+// are made, the last call overrides the previous call values.
+func WithEndpointResolverWithOptions(v aws.EndpointResolverWithOptions) LoadOptionsFunc {
+	return func(o *LoadOptions) error {
+		o.EndpointResolverWithOptions = v
+		return nil
+	}
+}
+
 func (o LoadOptions) getLogger(ctx context.Context) (logging.Logger, bool, error) {
 	if o.Logger == nil {
 		return nil, false, nil

config/provider.go

@@ -336,6 +336,25 @@ func getEndpointResolver(ctx context.Context, configs configs) (f aws.EndpointRe
 	return
 }
 
+// endpointResolverWithOptionsProvider is an interface for retrieving an aws.EndpointResolverWithOptions from a configuration source
+type endpointResolverWithOptionsProvider interface {
+	getEndpointResolverWithOptions(ctx context.Context) (aws.EndpointResolverWithOptions, bool, error)
+}
+
+// getEndpointResolver searches the provided config sources for a EndpointResolverFunc that can be used
+// to configure the aws.Config.EndpointResolver value.
+func getEndpointResolverWithOptions(ctx context.Context, configs configs) (f aws.EndpointResolverWithOptions, found bool, err error) {
+	for _, c := range configs {
+		if p, ok := c.(endpointResolverWithOptionsProvider); ok {
+			f, found, err = p.getEndpointResolverWithOptions(ctx)
+			if err != nil || found {
+				break
+			}
+		}
+	}
+	return
+}
+
 // loggerProvider is an interface for retrieving a logging.Logger from a configuration source.
 type loggerProvider interface {
 	getLogger(ctx context.Context) (logging.Logger, bool, error)

config/resolve.go

@@ -166,6 +166,22 @@ func resolveEndpointResolver(ctx context.Context, cfg *aws.Config, configs confi
 	return nil
 }
 
+// resolveEndpointResolver extracts the first instance of a EndpointResolverFunc from the config slice
+// and sets the functions result on the aws.Config.EndpointResolver
+func resolveEndpointResolverWithOptions(ctx context.Context, cfg *aws.Config, configs configs) error {
+	endpointResolver, found, err := getEndpointResolverWithOptions(ctx, configs)
+	if err != nil {
+		return err
+	}
+	if !found {
+		return nil
+	}
+
+	cfg.EndpointResolverWithOptions = endpointResolver
+
+	return nil
+}
+
 func resolveLogger(ctx context.Context, cfg *aws.Config, configs configs) error {
 	logger, found, err := getLogger(ctx, configs)
 	if err != nil {

config/resolve_credentials_test.go

@@ -30,7 +30,7 @@ func swapECSContainerURI(path string) func() {
 	}
 }
 
-func setupCredentialsEndpoints(t *testing.T) (aws.EndpointResolver, func()) {
+func setupCredentialsEndpoints(t *testing.T) (aws.EndpointResolverWithOptions, func()) {
 	ecsMetadataServer := httptest.NewServer(http.HandlerFunc(
 		func(w http.ResponseWriter, r *http.Request) {
 			if r.URL.Path == "/ECS" {
@@ -95,8 +95,8 @@ func setupCredentialsEndpoints(t *testing.T) (aws.EndpointResolver, func()) {
 				UnixNano()/int64(time.Millisecond))))
 	}))
 
-	resolver := aws.EndpointResolverFunc(
-		func(service, region string) (aws.Endpoint, error) {
+	resolver := aws.EndpointResolverWithOptionsFunc(
+		func(service, region string, options ...interface{}) (aws.Endpoint, error) {
 			switch service {
 			case sts.ServiceID:
 				return aws.Endpoint{
@@ -394,7 +394,7 @@ func TestSharedConfigCredentialSource(t *testing.T) {
 			var credChain []string
 
 			loadOptions := []func(*LoadOptions) error{
-				WithEndpointResolver(endpointResolver),
+				WithEndpointResolverWithOptions(endpointResolver),
 				WithAPIOptions([]func(*middleware.Stack) error{
 					func(stack *middleware.Stack) error {
 						return stack.Initialize.Add(middleware.InitializeMiddlewareFunc("GetRoleArns", func(ctx context.Context, in middleware.InitializeInput, next middleware.InitializeHandler,