feat(middleware-signing): support SigV4 for non AWS services

There is no regionInfo to determine signingService. The signingName
will instead directly come from input. And region will be used as
signingRegion.

Author: gosar

packages/middleware-signing/src/configurations.ts

@@ -32,6 +32,29 @@ export interface AwsAuthInputConfig {
    */
   signingRegion?: string;
 }
+
+export interface CustomAwsAuthInputConfig {
+  /**
+   * The credentials used to sign requests.
+   */
+  credentials?: Credentials | Provider<Credentials>;
+
+  /**
+   * The signer to use when signing requests.
+   */
+  signer?: RequestSigner | Provider<RequestSigner>;
+
+  /**
+   * Whether to escape request path when signing the request.
+   */
+  signingEscapePath?: boolean;
+
+  /**
+   * An offset value in milliseconds to apply to all signing times.
+   */
+  systemClockOffset?: number;
+}
+
 interface PreviouslyResolved {
   credentialDefaultProvider: (input: any) => Provider<Credentials>;
   region: string | Provider<string>;
@@ -40,13 +63,23 @@ interface PreviouslyResolved {
   serviceId: string;
   sha256: HashConstructor;
 }
+
+interface CustomPreviouslyResolved {
+  credentialDefaultProvider: (input: any) => Provider<Credentials>;
+  region: string | Provider<string>;
+  signingName: string;
+  sha256: HashConstructor;
+}
+
 export interface AwsAuthResolvedConfig {
   credentials: Provider<Credentials>;
   signer: Provider<RequestSigner>;
   signingEscapePath: boolean;
   systemClockOffset: number;
 }
 
+export interface CustomAwsAuthResolvedConfig extends AwsAuthResolvedConfig {}
+
 export const resolveAwsAuthConfig = <T>(
   input: T & AwsAuthInputConfig & PreviouslyResolved
 ): T & AwsAuthResolvedConfig => {
@@ -91,6 +124,37 @@ export const resolveAwsAuthConfig = <T>(
   };
 };
 
+// TODO: reduce code duplication
+export const resolveCustomAwsAuthConfig = <T>(
+  input: T & CustomAwsAuthInputConfig & CustomPreviouslyResolved
+): T & CustomAwsAuthResolvedConfig => {
+  const normalizedCreds = input.credentials
+    ? normalizeCredentialProvider(input.credentials)
+    : input.credentialDefaultProvider(input as any);
+  const { signingEscapePath = true, systemClockOffset = input.systemClockOffset || 0, sha256 } = input;
+  let signer: Provider<RequestSigner>;
+  if (input.signer) {
+    //if signer is supplied by user, normalize it to a function returning a promise for signer.
+    signer = normalizeProvider(input.signer);
+  } else {
+    signer = normalizeProvider(new SignatureV4({
+      credentials: normalizedCreds,
+      region: input.region,
+      service: input.signingName,
+      sha256,
+      uriEscapePath: signingEscapePath,
+    }));
+  }
+
+  return {
+    ...input,
+    systemClockOffset,
+    signingEscapePath,
+    credentials: normalizedCreds,
+    signer,
+  };
+};
+
 const normalizeProvider = <T>(input: T | Provider<T>): Provider<T> => {
   if (typeof input === "object") {
     const promisified = Promise.resolve(input);

packages/middleware-signing/src/middleware.ts

@@ -58,3 +58,5 @@ export const getAwsAuthPlugin = (options: AwsAuthResolvedConfig): Pluggable<any,
     clientStack.addRelativeTo(awsAuthMiddleware(options), awsAuthMiddlewareOptions);
   },
 });
+
+export const getCustomAwsAuthPlugin = getAwsAuthPlugin;