fix(config-resolver): add options for utility functions (aws#2712)

packages/config-resolver/src/endpointsConfig/getEndpointFromRegion.ts

@@ -1,6 +1,13 @@
-import { EndpointsInputConfig, PreviouslyResolved } from "./configurations";
+import { Provider, RegionInfoProvider, UrlParser } from "@aws-sdk/types";
 
-export const getEndpointFromRegion = async (input: EndpointsInputConfig & PreviouslyResolved) => {
+interface GetEndpointFromRegionOptions {
+  region: Provider<string>;
+  tls?: boolean;
+  regionInfoProvider: RegionInfoProvider;
+  urlParser: UrlParser;
+}
+
+export const getEndpointFromRegion = async (input: GetEndpointFromRegionOptions) => {
   const { tls = true } = input;
   const region = await input.region();
 

packages/config-resolver/src/endpointsConfig/index.ts

@@ -1,2 +1 @@
-export * from "./configurations";
 export * from "./resolveEndpointsConfig";

packages/config-resolver/src/endpointsConfig/normalizeEndpoint.ts

@@ -1,17 +1,17 @@
-import { Endpoint, Provider } from "@aws-sdk/types";
+import { Endpoint, Provider, UrlParser } from "@aws-sdk/types";
 
-import { EndpointsInputConfig, PreviouslyResolved } from "./configurations";
+interface NormalizeEndpointOptions {
+  endpoint: string | Endpoint | Provider<Endpoint>;
+  urlParser: UrlParser;
+}
 
-export const normalizeEndpoint = ({
-  endpoint,
-  urlParser,
-}: EndpointsInputConfig & PreviouslyResolved): Provider<Endpoint> => {
+export const normalizeEndpoint = ({ endpoint, urlParser }: NormalizeEndpointOptions): Provider<Endpoint> => {
   if (typeof endpoint === "string") {
     const promisified = Promise.resolve(urlParser(endpoint));
     return () => promisified;
   } else if (typeof endpoint === "object") {
     const promisified = Promise.resolve(endpoint);
     return () => promisified;
   }
-  return endpoint!;
+  return endpoint;
 };

packages/config-resolver/src/endpointsConfig/resolveEndpointsConfig.ts

@@ -1,12 +1,46 @@
-import { EndpointsInputConfig, EndpointsResolvedConfig, PreviouslyResolved } from "./configurations";
+import { Endpoint, Provider, RegionInfoProvider, UrlParser } from "@aws-sdk/types";
+
 import { getEndpointFromRegion } from "./getEndpointFromRegion";
 import { normalizeEndpoint } from "./normalizeEndpoint";
 
+export interface EndpointsInputConfig {
+  /**
+   * The fully qualified endpoint of the webservice. This is only required when using a custom endpoint (for example, when using a local version of S3).
+   */
+  endpoint?: string | Endpoint | Provider<Endpoint>;
+
+  /**
+   * Whether TLS is enabled for requests.
+   */
+  tls?: boolean;
+}
+
+interface PreviouslyResolved {
+  regionInfoProvider: RegionInfoProvider;
+  urlParser: UrlParser;
+  region: Provider<string>;
+}
+
+export interface EndpointsResolvedConfig extends Required<EndpointsInputConfig> {
+  /**
+   * Resolved value for input {@link EndpointsResolvedConfig.endpoint}
+   */
+  endpoint: Provider<Endpoint>;
+
+  /**
+   * Whether the endpoint is specified by caller.
+   * @internal
+   */
+  isCustomEndpoint: boolean;
+}
+
 export const resolveEndpointsConfig = <T>(
   input: T & EndpointsInputConfig & PreviouslyResolved
 ): T & EndpointsResolvedConfig => ({
   ...input,
   tls: input.tls ?? true,
-  endpoint: input.endpoint ? normalizeEndpoint(input) : () => getEndpointFromRegion(input),
+  endpoint: input.endpoint
+    ? normalizeEndpoint({ ...input, endpoint: input.endpoint })
+    : () => getEndpointFromRegion(input),
   isCustomEndpoint: input.endpoint ? true : false,
 });